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@@ -10,6 +10,10 @@ Return the last reference token.
Last reference token.
## Exception safety
Strong exception safety: if an exception occurs, the original value stays intact.
## Exceptions
Throws [out_of_range.405](../../home/exceptions.md#jsonexceptionout_of_range405) if the JSON pointer has no parent.
@@ -34,6 +38,13 @@ Constant.
--8<-- "examples/json_pointer__back.output"
```
## See also
- [front](front.md) return first reference token
- [pop_back](pop_back.md) remove the last reference token
- [push_back](push_back.md) append an unescaped token at the end of the pointer
- [parent_pointer](parent_pointer.md) returns the parent of this JSON pointer
## Version history
- Added in version 3.6.0.
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<!doctype html><html lang=en class=no-js> <head><meta charset=utf-8><meta name=viewport content="width=device-width,initial-scale=1"><meta name=author content="Niels Lohmann"><link href="https://json.nlohmann.me/api/json_pointer/back/" rel="canonical"><link href=../json_pointer/ rel=prev><link href=../empty/ rel=next><link rel=icon href=../../../assets/images/favicon.png><meta name=generator content="mkdocs-1.6.1, mkdocs-material-9.7.7"><title>back - JSON for Modern C++</title><link rel=stylesheet href=../../../assets/stylesheets/main.ec1eaa64.min.css><link rel=stylesheet href=../../../assets/stylesheets/palette.ab4e12ef.min.css><link rel="stylesheet" href="../../../assets/external/fonts.googleapis.com/css.61a430c9.css"><style>:root{--md-text-font:"Roboto";--md-code-font:"JetBrains Mono"}</style><link rel=stylesheet href=../../../css/custom.css><script>__md_scope=new 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data-md-component=logo> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M12 8a3 3 0 0 0 3-3 3 3 0 0 0-3-3 3 3 0 0 0-3 3 3 3 0 0 0 3 3m0 3.54C9.64 9.35 6.5 8 3 8v11c3.5 0 6.64 1.35 9 3.54 2.36-2.19 5.5-3.54 9-3.54V8c-3.5 0-6.64 1.35-9 3.54"/></svg> </a> <label class="md-header__button md-icon" for=__drawer> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M3 6h18v2H3zm0 5h18v2H3zm0 5h18v2H3z"/></svg> </label> <div class=md-header__title data-md-component=header-title> <div class=md-header__ellipsis> <div class=md-header__topic> <span class=md-ellipsis> JSON for Modern C++ </span> </div> <div class=md-header__topic data-md-component=header-topic> <span class=md-ellipsis> back </span> </div> </div> </div> <form class=md-header__option data-md-component=palette> <input class=md-option data-md-color-media="(prefers-color-scheme: light)" data-md-color-scheme=default data-md-color-primary=indigo data-md-color-accent=indigo aria-label="Switch to dark mode" 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</code></pre></div> <p>Return the last reference token.</p> <h2 id=return-value>Return value<a class=headerlink href=#return-value title="Permanent link">&para;</a></h2> <p>Last reference token.</p> <h2 id=exceptions>Exceptions<a class=headerlink href=#exceptions title="Permanent link">&para;</a></h2> <p>Throws <a href=../../../home/exceptions/#jsonexceptionout_of_range405>out_of_range.405</a> if the <abbr title="JavaScript Object Notation">JSON</abbr> pointer has no parent.</p> <h2 id=complexity>Complexity<a class=headerlink href=#complexity title="Permanent link">&para;</a></h2> <p>Constant.</p> <h2 id=examples>Examples<a class=headerlink href=#examples title="Permanent link">&para;</a></h2> <details class=example> <summary>Example</summary> <p>The example shows the usage of <code>back</code>.</p> <div class=highlight><pre><span></span><code><span class=cp>#include</span><span class=w> </span><span class=cpf>&lt;iostream&gt;</span>
<!doctype html><html lang=en class=no-js> <head><meta charset=utf-8><meta name=viewport content="width=device-width,initial-scale=1"><meta name=author content="Niels Lohmann"><link href="https://json.nlohmann.me/api/json_pointer/back/" rel="canonical"><link href=../json_pointer/ rel=prev><link href=../empty/ rel=next><link rel=icon href=../../../assets/images/favicon.png><meta name=generator content="mkdocs-1.6.1, mkdocs-material-9.7.7"><title>back - JSON for Modern C++</title><link rel=stylesheet href=../../../assets/stylesheets/main.ec1eaa64.min.css><link rel=stylesheet href=../../../assets/stylesheets/palette.ab4e12ef.min.css><link rel="stylesheet" href="../../../assets/external/fonts.googleapis.com/css.61a430c9.css"><style>:root{--md-text-font:"Roboto";--md-code-font:"JetBrains Mono"}</style><link rel=stylesheet href=../../../css/custom.css><script>__md_scope=new URL("../../..",location),__md_hash=e=>[...e].reduce(((e,_)=>(e<<5)-e+_.charCodeAt(0)),0),__md_get=(e,_=localStorage,t=__md_scope)=>JSON.parse(_.getItem(t.pathname+"."+e)),__md_set=(e,_,t=localStorage,a=__md_scope)=>{try{t.setItem(a.pathname+"."+e,JSON.stringify(_))}catch(e){}}</script></head> <body dir=ltr data-md-color-scheme=default data-md-color-primary=indigo data-md-color-accent=indigo> <input class=md-toggle data-md-toggle=drawer type=checkbox id=__drawer autocomplete=off> <input class=md-toggle data-md-toggle=search type=checkbox id=__search autocomplete=off> <label class=md-overlay for=__drawer></label> <div data-md-component=skip> <a href=#nlohmannjson_pointerback class=md-skip> Skip to content </a> </div> <div data-md-component=announce> </div> <header class=md-header data-md-component=header> <nav class="md-header__inner md-grid" aria-label=Header> <a href=../../.. title="JSON for Modern C++" class="md-header__button md-logo" aria-label="JSON for Modern C++" data-md-component=logo> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M12 8a3 3 0 0 0 3-3 3 3 0 0 0-3-3 3 3 0 0 0-3 3 3 3 0 0 0 3 3m0 3.54C9.64 9.35 6.5 8 3 8v11c3.5 0 6.64 1.35 9 3.54 2.36-2.19 5.5-3.54 9-3.54V8c-3.5 0-6.64 1.35-9 3.54"/></svg> </a> <label class="md-header__button md-icon" for=__drawer> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M3 6h18v2H3zm0 5h18v2H3zm0 5h18v2H3z"/></svg> </label> <div class=md-header__title data-md-component=header-title> <div class=md-header__ellipsis> <div class=md-header__topic> <span class=md-ellipsis> JSON for Modern C++ </span> </div> <div class=md-header__topic data-md-component=header-topic> <span class=md-ellipsis> back </span> </div> </div> </div> <form class=md-header__option data-md-component=palette> <input class=md-option data-md-color-media="(prefers-color-scheme: light)" data-md-color-scheme=default data-md-color-primary=indigo data-md-color-accent=indigo aria-label="Switch to dark mode" 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12 4 15.31V20h4.69L12 23.31 15.31 20H20v-4.69L23.31 12z"/></svg> </label> </form> <script>var palette=__md_get("__palette");if(palette&&palette.color){if("(prefers-color-scheme)"===palette.color.media){var media=matchMedia("(prefers-color-scheme: light)"),input=document.querySelector(media.matches?"[data-md-color-media='(prefers-color-scheme: light)']":"[data-md-color-media='(prefers-color-scheme: dark)']");palette.color.media=input.getAttribute("data-md-color-media"),palette.color.scheme=input.getAttribute("data-md-color-scheme"),palette.color.primary=input.getAttribute("data-md-color-primary"),palette.color.accent=input.getAttribute("data-md-color-accent")}for(var[key,value]of Object.entries(palette.color))document.body.setAttribute("data-md-color-"+key,value)}</script> <label class="md-header__button md-icon" for=__search> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M9.5 3A6.5 6.5 0 0 1 16 9.5c0 1.61-.59 3.09-1.56 4.23l.27.27h.79l5 5-1.5 1.5-5-5v-.79l-.27-.27A6.52 6.52 0 0 1 9.5 16 6.5 6.5 0 0 1 3 9.5 6.5 6.5 0 0 1 9.5 3m0 2C7 5 5 7 5 9.5S7 14 9.5 14 14 12 14 9.5 12 5 9.5 5"/></svg> </label> Line truncated
</code></pre></div> <p>Return the last reference token.</p> <h2 id=return-value>Return value<a class=headerlink href=#return-value title="Permanent link">&para;</a></h2> <p>Last reference token.</p> <h2 id=exception-safety>Exception safety<a class=headerlink href=#exception-safety title="Permanent link">&para;</a></h2> <p>Strong exception safety: if an exception occurs, the original value stays intact.</p> <h2 id=exceptions>Exceptions<a class=headerlink href=#exceptions title="Permanent link">&para;</a></h2> <p>Throws <a href=../../../home/exceptions/#jsonexceptionout_of_range405>out_of_range.405</a> if the <abbr title="JavaScript Object Notation">JSON</abbr> pointer has no parent.</p> <h2 id=complexity>Complexity<a class=headerlink href=#complexity title="Permanent link">&para;</a></h2> <p>Constant.</p> <h2 id=examples>Examples<a class=headerlink href=#examples title="Permanent link">&para;</a></h2> <details class=example> <summary>Example</summary> <p>The example shows the usage of <code>back</code>.</p> <div class=highlight><pre><span></span><code><span class=cp>#include</span><span class=w> </span><span class=cpf>&lt;iostream&gt;</span>
<span class=cp>#include</span><span class=w> </span><span class=cpf>&lt;nlohmann/json.hpp&gt;</span>
<span class=k>using</span><span class=w> </span><span class=n>json</span><span class=w> </span><span class=o>=</span><span class=w> </span><span class=n>nlohmann</span><span class=o>::</span><span class=n>json</span><span class=p>;</span>
@@ -16,4 +16,4 @@
<span class=p>}</span>
</code></pre></div> <p>Output:</p> <div class=highlight><pre><span></span><code><span class=err>las</span><span class=kc>t</span><span class=w> </span><span class=err>re</span><span class=kc>feren</span><span class=err>ce</span><span class=w> </span><span class=kc>t</span><span class=err>oke</span><span class=kc>n</span><span class=w> </span><span class=err>o</span><span class=kc>f</span><span class=w> </span><span class=s2>"/foo"</span><span class=w> </span><span class=err>is</span><span class=w> </span><span class=s2>"foo"</span>
<span class=err>las</span><span class=kc>t</span><span class=w> </span><span class=err>re</span><span class=kc>feren</span><span class=err>ce</span><span class=w> </span><span class=kc>t</span><span class=err>oke</span><span class=kc>n</span><span class=w> </span><span class=err>o</span><span class=kc>f</span><span class=w> </span><span class=s2>"/foo/0"</span><span class=w> </span><span class=err>is</span><span class=w> </span><span class=s2>"0"</span>
</code></pre></div> </details> <h2 id=version-history>Version history<a class=headerlink href=#version-history title="Permanent link">&para;</a></h2> <ul> <li>Added in version 3.6.0.</li> <li>Changed return type to <code>string_t</code> in version 3.11.0.</li> </ul> <!-- https://squidfunk.github.io/mkdocs-material/reference/tooltips/#adding-a-glossary --> <aside class=md-source-file> <span class=md-source-file__fact> <span class=md-icon title="Last update"> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M21 13.1c-.1 0-.3.1-.4.2l-1 1 2.1 2.1 1-1c.2-.2.2-.6 0-.8l-1.3-1.3c-.1-.1-.2-.2-.4-.2m-1.9 1.8-6.1 6V23h2.1l6.1-6.1zM12.5 7v5.2l4 2.4-1 1L11 13V7zM11 21.9c-5.1-.5-9-4.8-9-9.9C2 6.5 6.5 2 12 2c5.3 0 9.6 4.1 10 9.3-.3-.1-.6-.2-1-.2s-.7.1-1 .2C19.6 7.2 16.2 4 12 4c-4.4 0-8 3.6-8 8 0 4.1 3.1 7.5 7.1 7.9l-.1.2z"/></svg> </span> <span class="git-revision-date-localized-plugin git-revision-date-localized-plugin-date" title="October 2, 2026 09:23:55 UTC">October 2, 2026</span> </span> </aside> </article> </div> <script>var tabs=__md_get("__tabs");if(Array.isArray(tabs))e:for(var set of document.querySelectorAll(".tabbed-set")){var labels=set.querySelector(".tabbed-labels");for(var tab of tabs)for(var label of labels.getElementsByTagName("label"))if(label.innerText.trim()===tab){var input=document.getElementById(label.htmlFor);input.checked=!0;continue e}}</script> <script>var target=document.getElementById(location.hash.slice(1));target&&target.name&&(target.checked=target.name.startsWith("__tabbed_"))</script> </div> <button type=button class="md-top md-icon" data-md-component=top hidden> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M13 20h-2V8l-5.5 5.5-1.42-1.42L12 4.16l7.92 7.92-1.42 1.42L13 8z"/></svg> Back to top </button> </main> <footer class=md-footer> <div class="md-footer-meta md-typeset"> <div class="md-footer-meta__inner md-grid"> <div class=md-copyright> <div class=md-copyright__highlight> Copyright &copy; 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</code></pre></div> </details> <h2 id=see-also>See also<a class=headerlink href=#see-also title="Permanent link">&para;</a></h2> <ul> <li><a href=../front/ >front</a> return first reference token</li> <li><a href=../pop_back/ >pop_back</a> remove the last reference token</li> <li><a href=../push_back/ >push_back</a> append an unescaped token at the end of the pointer</li> <li><a href=../parent_pointer/ >parent_pointer</a> returns the parent of this <abbr title="JavaScript Object Notation">JSON</abbr> pointer</li> </ul> <h2 id=version-history>Version history<a class=headerlink href=#version-history title="Permanent link">&para;</a></h2> <ul> <li>Added in version 3.6.0.</li> <li>Changed return type to <code>string_t</code> in version 3.11.0.</li> </ul> <!-- https://squidfunk.github.io/mkdocs-material/reference/tooltips/#adding-a-glossary --> <aside class=md-source-file> <span class=md-source-file__fact> <span class=md-icon title="Last update"> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M21 13.1c-.1 0-.3.1-.4.2l-1 1 2.1 2.1 1-1c.2-.2.2-.6 0-.8l-1.3-1.3c-.1-.1-.2-.2-.4-.2m-1.9 1.8-6.1 6V23h2.1l6.1-6.1zM12.5 7v5.2l4 2.4-1 1L11 13V7zM11 21.9c-5.1-.5-9-4.8-9-9.9C2 6.5 6.5 2 12 2c5.3 0 9.6 4.1 10 9.3-.3-.1-.6-.2-1-.2s-.7.1-1 .2C19.6 7.2 16.2 4 12 4c-4.4 0-8 3.6-8 8 0 4.1 3.1 7.5 7.1 7.9l-.1.2z"/></svg> </span> <span class="git-revision-date-localized-plugin git-revision-date-localized-plugin-date" title="October 2, 2026 09:32:15 UTC">October 2, 2026</span> </span> </aside> </article> </div> <script>var tabs=__md_get("__tabs");if(Array.isArray(tabs))e:for(var set of document.querySelectorAll(".tabbed-set")){var labels=set.querySelector(".tabbed-labels");for(var tab of tabs)for(var label of labels.getElementsByTagName("label"))if(label.innerText.trim()===tab){var input=document.getElementById(label.htmlFor);input.checked=!0;continue e}}</script> <script>var target=document.getElementById(location.hash.slice(1));target&&target.name&&(target.checked=target.name.startsWith("__tabbed_"))</script> </div> <button type=button class="md-top md-icon" data-md-component=top hidden> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M13 20h-2V8l-5.5 5.5-1.42-1.42L12 4.16l7.92 7.92-1.42 1.42L13 8z"/></svg> Back to top </button> </main> <footer class=md-footer> <div class="md-footer-meta md-typeset"> <div class="md-footer-meta__inner md-grid"> <div class=md-copyright> <div class=md-copyright__highlight> Copyright &copy; 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+11
View File
@@ -10,6 +10,10 @@ Return the last reference token.
Last reference token.
## Exception safety
Strong exception safety: if an exception occurs, the original value stays intact.
## Exceptions
Throws [out_of_range.405](https://json.nlohmann.me/home/exceptions/#jsonexceptionout_of_range405) if the JSON pointer has no parent.
@@ -49,6 +53,13 @@ last reference token of "/foo" is "foo"
last reference token of "/foo/0" is "0"
```
## See also
- [front](https://json.nlohmann.me/api/json_pointer/front/index.md) return first reference token
- [pop_back](https://json.nlohmann.me/api/json_pointer/pop_back/index.md) remove the last reference token
- [push_back](https://json.nlohmann.me/api/json_pointer/push_back/index.md) append an unescaped token at the end of the pointer
- [parent_pointer](https://json.nlohmann.me/api/json_pointer/parent_pointer/index.md) returns the parent of this JSON pointer
## Version history
- Added in version 3.6.0.
+6
View File
@@ -34,6 +34,12 @@ Constant.
--8<-- "examples/json_pointer__empty.output"
```
## See also
- [front](front.md) return first reference token
- [back](back.md) return last reference token
- [to_string](to_string.md) return a string representation of the JSON pointer
## Version history
Added in version 3.6.0.
+2 -2
View File
@@ -1,4 +1,4 @@
<!doctype html><html lang=en class=no-js> <head><meta charset=utf-8><meta name=viewport content="width=device-width,initial-scale=1"><meta name=author content="Niels Lohmann"><link href="https://json.nlohmann.me/api/json_pointer/empty/" rel="canonical"><link href=../back/ rel=prev><link href=../front/ rel=next><link rel=icon href=../../../assets/images/favicon.png><meta name=generator content="mkdocs-1.6.1, mkdocs-material-9.7.7"><title>empty - JSON for Modern C++</title><link rel=stylesheet href=../../../assets/stylesheets/main.ec1eaa64.min.css><link rel=stylesheet href=../../../assets/stylesheets/palette.ab4e12ef.min.css><link rel="stylesheet" href="../../../assets/external/fonts.googleapis.com/css.61a430c9.css"><style>:root{--md-text-font:"Roboto";--md-code-font:"JetBrains Mono"}</style><link rel=stylesheet href=../../../css/custom.css><script>__md_scope=new 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<!doctype html><html lang=en class=no-js> <head><meta charset=utf-8><meta name=viewport content="width=device-width,initial-scale=1"><meta name=author content="Niels Lohmann"><link href="https://json.nlohmann.me/api/json_pointer/empty/" rel="canonical"><link href=../back/ rel=prev><link href=../front/ rel=next><link rel=icon href=../../../assets/images/favicon.png><meta name=generator content="mkdocs-1.6.1, mkdocs-material-9.7.7"><title>empty - JSON for Modern C++</title><link rel=stylesheet href=../../../assets/stylesheets/main.ec1eaa64.min.css><link rel=stylesheet href=../../../assets/stylesheets/palette.ab4e12ef.min.css><link rel="stylesheet" href="../../../assets/external/fonts.googleapis.com/css.61a430c9.css"><style>:root{--md-text-font:"Roboto";--md-code-font:"JetBrains Mono"}</style><link rel=stylesheet href=../../../css/custom.css><script>__md_scope=new 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</code></pre></div> <p>Return whether the pointer points to the root document.</p> <h2 id=return-value>Return value<a class=headerlink href=#return-value title="Permanent link">&para;</a></h2> <p><code class=highlight><span class=nb>true</span></code> iff the <abbr title="JavaScript Object Notation">JSON</abbr> pointer points to the root document.</p> <h2 id=exception-safety>Exception safety<a class=headerlink href=#exception-safety title="Permanent link">&para;</a></h2> <p>No-throw guarantee: this function never throws exceptions.</p> <h2 id=complexity>Complexity<a class=headerlink href=#complexity title="Permanent link">&para;</a></h2> <p>Constant.</p> <h2 id=examples>Examples<a class=headerlink href=#examples title="Permanent link">&para;</a></h2> <details class=example> <summary>Example</summary> <p>The example shows the result of <code>empty</code> for different <abbr title="JavaScript Object Notation">JSON</abbr> Pointers.</p> <div class=highlight><pre><span></span><code><span class=cp>#include</span><span class=w> </span><span class=cpf>&lt;iostream&gt;</span>
<span class=cp>#include</span><span class=w> </span><span class=cpf>&lt;nlohmann/json.hpp&gt;</span>
@@ -23,4 +23,4 @@
<span class=nt>""</span><span class=p>:</span><span class=w> </span><span class=kc>true</span>
<span class=nt>"/foo"</span><span class=p>:</span><span class=w> </span><span class=kc>false</span>
<span class=nt>"/foo/0"</span><span class=p>:</span><span class=w> </span><span class=kc>false</span>
</code></pre></div> </details> <h2 id=version-history>Version history<a class=headerlink href=#version-history title="Permanent link">&para;</a></h2> <p>Added in version 3.6.0.</p> <!-- https://squidfunk.github.io/mkdocs-material/reference/tooltips/#adding-a-glossary --> <aside class=md-source-file> <span class=md-source-file__fact> <span class=md-icon title="Last update"> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M21 13.1c-.1 0-.3.1-.4.2l-1 1 2.1 2.1 1-1c.2-.2.2-.6 0-.8l-1.3-1.3c-.1-.1-.2-.2-.4-.2m-1.9 1.8-6.1 6V23h2.1l6.1-6.1zM12.5 7v5.2l4 2.4-1 1L11 13V7zM11 21.9c-5.1-.5-9-4.8-9-9.9C2 6.5 6.5 2 12 2c5.3 0 9.6 4.1 10 9.3-.3-.1-.6-.2-1-.2s-.7.1-1 .2C19.6 7.2 16.2 4 12 4c-4.4 0-8 3.6-8 8 0 4.1 3.1 7.5 7.1 7.9l-.1.2z"/></svg> </span> <span class="git-revision-date-localized-plugin git-revision-date-localized-plugin-date" title="October 2, 2026 09:23:55 UTC">October 2, 2026</span> </span> </aside> </article> </div> <script>var tabs=__md_get("__tabs");if(Array.isArray(tabs))e:for(var set of document.querySelectorAll(".tabbed-set")){var labels=set.querySelector(".tabbed-labels");for(var tab of tabs)for(var label of labels.getElementsByTagName("label"))if(label.innerText.trim()===tab){var input=document.getElementById(label.htmlFor);input.checked=!0;continue e}}</script> <script>var target=document.getElementById(location.hash.slice(1));target&&target.name&&(target.checked=target.name.startsWith("__tabbed_"))</script> </div> <button type=button class="md-top md-icon" data-md-component=top hidden> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M13 20h-2V8l-5.5 5.5-1.42-1.42L12 4.16l7.92 7.92-1.42 1.42L13 8z"/></svg> Back to top </button> </main> <footer class=md-footer> <div class="md-footer-meta md-typeset"> <div class="md-footer-meta__inner md-grid"> <div class=md-copyright> <div class=md-copyright__highlight> Copyright &copy; 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</code></pre></div> </details> <h2 id=see-also>See also<a class=headerlink href=#see-also title="Permanent link">&para;</a></h2> <ul> <li><a href=../front/ >front</a> return first reference token</li> <li><a href=../back/ >back</a> return last reference token</li> <li><a href=../to_string/ >to_string</a> return a string representation of the <abbr title="JavaScript Object Notation">JSON</abbr> pointer</li> </ul> <h2 id=version-history>Version history<a class=headerlink href=#version-history title="Permanent link">&para;</a></h2> <p>Added in version 3.6.0.</p> <!-- https://squidfunk.github.io/mkdocs-material/reference/tooltips/#adding-a-glossary --> <aside class=md-source-file> <span class=md-source-file__fact> <span class=md-icon title="Last update"> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M21 13.1c-.1 0-.3.1-.4.2l-1 1 2.1 2.1 1-1c.2-.2.2-.6 0-.8l-1.3-1.3c-.1-.1-.2-.2-.4-.2m-1.9 1.8-6.1 6V23h2.1l6.1-6.1zM12.5 7v5.2l4 2.4-1 1L11 13V7zM11 21.9c-5.1-.5-9-4.8-9-9.9C2 6.5 6.5 2 12 2c5.3 0 9.6 4.1 10 9.3-.3-.1-.6-.2-1-.2s-.7.1-1 .2C19.6 7.2 16.2 4 12 4c-4.4 0-8 3.6-8 8 0 4.1 3.1 7.5 7.1 7.9l-.1.2z"/></svg> </span> <span class="git-revision-date-localized-plugin git-revision-date-localized-plugin-date" title="October 2, 2026 09:32:15 UTC">October 2, 2026</span> </span> </aside> </article> </div> <script>var tabs=__md_get("__tabs");if(Array.isArray(tabs))e:for(var set of document.querySelectorAll(".tabbed-set")){var labels=set.querySelector(".tabbed-labels");for(var tab of tabs)for(var label of labels.getElementsByTagName("label"))if(label.innerText.trim()===tab){var input=document.getElementById(label.htmlFor);input.checked=!0;continue e}}</script> <script>var target=document.getElementById(location.hash.slice(1));target&&target.name&&(target.checked=target.name.startsWith("__tabbed_"))</script> </div> <button type=button class="md-top md-icon" data-md-component=top hidden> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M13 20h-2V8l-5.5 5.5-1.42-1.42L12 4.16l7.92 7.92-1.42 1.42L13 8z"/></svg> Back to top </button> </main> <footer class=md-footer> <div class="md-footer-meta md-typeset"> <div class="md-footer-meta__inner md-grid"> <div class=md-copyright> <div class=md-copyright__highlight> Copyright &copy; 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+6
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@@ -56,6 +56,12 @@ Output:
"/foo/0": false
```
## See also
- [front](https://json.nlohmann.me/api/json_pointer/front/index.md) return first reference token
- [back](https://json.nlohmann.me/api/json_pointer/back/index.md) return last reference token
- [to_string](https://json.nlohmann.me/api/json_pointer/to_string/index.md) return a string representation of the JSON pointer
## Version history
Added in version 3.6.0.
+10
View File
@@ -10,6 +10,10 @@ Return the first reference token.
First reference token.
## Exception safety
Strong exception safety: if an exception occurs, the original value stays intact.
## Exceptions
Throws [out_of_range.405](../../home/exceptions.md#jsonexceptionout_of_range405) if the JSON pointer has no parent.
@@ -34,6 +38,12 @@ Constant.
--8<-- "examples/json_pointer__front.output"
```
## See also
- [back](back.md) return last reference token
- [pop_front](pop_front.md) remove the first reference token
- [push_front](push_front.md) append an unescaped token at the start of the pointer
## Version history
- Added in version 3.13.0.
+3 -3
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@@ -1,5 +1,5 @@
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</code></pre></div> <p>Return the first reference token.</p> <h2 id=return-value>Return value<a class=headerlink href=#return-value title="Permanent link">&para;</a></h2> <p>First reference token.</p> <h2 id=exceptions>Exceptions<a class=headerlink href=#exceptions title="Permanent link">&para;</a></h2> <p>Throws <a href=../../../home/exceptions/#jsonexceptionout_of_range405>out_of_range.405</a> if the <abbr title="JavaScript Object Notation">JSON</abbr> pointer has no parent.</p> <h2 id=complexity>Complexity<a class=headerlink href=#complexity title="Permanent link">&para;</a></h2> <p>Constant.</p> <h2 id=examples>Examples<a class=headerlink href=#examples title="Permanent link">&para;</a></h2> <details class=example> <summary>Example</summary> <p>The example shows the usage of <code>front</code>.</p> <div class=highlight><pre><span></span><code><span class=cp>#include</span><span class=w> </span><span class=cpf>&lt;iostream&gt;</span>
<!doctype html><html lang=en class=no-js> <head><meta charset=utf-8><meta name=viewport content="width=device-width,initial-scale=1"><meta name=author content="Niels Lohmann"><link href="https://json.nlohmann.me/api/json_pointer/front/" rel="canonical"><link href=../empty/ rel=prev><link href=../operator_string_t/ rel=next><link rel=icon href=../../../assets/images/favicon.png><meta name=generator content="mkdocs-1.6.1, mkdocs-material-9.7.7"><title>front - JSON for Modern C++</title><link rel=stylesheet href=../../../assets/stylesheets/main.ec1eaa64.min.css><link rel=stylesheet href=../../../assets/stylesheets/palette.ab4e12ef.min.css><link rel="stylesheet" href="../../../assets/external/fonts.googleapis.com/css.61a430c9.css"><style>:root{--md-text-font:"Roboto";--md-code-font:"JetBrains Mono"}</style><link rel=stylesheet href=../../../css/custom.css><script>__md_scope=new 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data-md-component=logo> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M12 8a3 3 0 0 0 3-3 3 3 0 0 0-3-3 3 3 0 0 0-3 3 3 3 0 0 0 3 3m0 3.54C9.64 9.35 6.5 8 3 8v11c3.5 0 6.64 1.35 9 3.54 2.36-2.19 5.5-3.54 9-3.54V8c-3.5 0-6.64 1.35-9 3.54"/></svg> </a> <label class="md-header__button md-icon" for=__drawer> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M3 6h18v2H3zm0 5h18v2H3zm0 5h18v2H3z"/></svg> </label> <div class=md-header__title data-md-component=header-title> <div class=md-header__ellipsis> <div class=md-header__topic> <span class=md-ellipsis> JSON for Modern C++ </span> </div> <div class=md-header__topic data-md-component=header-topic> <span class=md-ellipsis> front </span> </div> </div> </div> <form class=md-header__option data-md-component=palette> <input class=md-option data-md-color-media="(prefers-color-scheme: light)" data-md-color-scheme=default data-md-color-primary=indigo data-md-color-accent=indigo aria-label="Switch to dark mode" 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</code></pre></div> <p>Return the first reference token.</p> <h2 id=return-value>Return value<a class=headerlink href=#return-value title="Permanent link">&para;</a></h2> <p>First reference token.</p> <h2 id=exception-safety>Exception safety<a class=headerlink href=#exception-safety title="Permanent link">&para;</a></h2> <p>Strong exception safety: if an exception occurs, the original value stays intact.</p> <h2 id=exceptions>Exceptions<a class=headerlink href=#exceptions title="Permanent link">&para;</a></h2> <p>Throws <a href=../../../home/exceptions/#jsonexceptionout_of_range405>out_of_range.405</a> if the <abbr title="JavaScript Object Notation">JSON</abbr> pointer has no parent.</p> <h2 id=complexity>Complexity<a class=headerlink href=#complexity title="Permanent link">&para;</a></h2> <p>Constant.</p> <h2 id=examples>Examples<a class=headerlink href=#examples title="Permanent link">&para;</a></h2> <details class=example> <summary>Example</summary> <p>The example shows the usage of <code>front</code>.</p> <div class=highlight><pre><span></span><code><span class=cp>#include</span><span class=w> </span><span class=cpf>&lt;iostream&gt;</span>
<span class=cp>#include</span><span class=w> </span><span class=cpf>&lt;nlohmann/json.hpp&gt;</span>
<span class=k>using</span><span class=w> </span><span class=n>json</span><span class=w> </span><span class=o>=</span><span class=w> </span><span class=n>nlohmann</span><span class=o>::</span><span class=n>json</span><span class=p>;</span>
@@ -16,4 +16,4 @@
<span class=p>}</span>
</code></pre></div> <p>Output:</p> <div class=highlight><pre><span></span><code><span class=kc>f</span><span class=err>irs</span><span class=kc>t</span><span class=w> </span><span class=err>re</span><span class=kc>feren</span><span class=err>ce</span><span class=w> </span><span class=kc>t</span><span class=err>oke</span><span class=kc>n</span><span class=w> </span><span class=err>o</span><span class=kc>f</span><span class=w> </span><span class=s2>"/foo"</span><span class=w> </span><span class=err>is</span><span class=w> </span><span class=s2>"foo"</span>
<span class=kc>f</span><span class=err>irs</span><span class=kc>t</span><span class=w> </span><span class=err>re</span><span class=kc>feren</span><span class=err>ce</span><span class=w> </span><span class=kc>t</span><span class=err>oke</span><span class=kc>n</span><span class=w> </span><span class=err>o</span><span class=kc>f</span><span class=w> </span><span class=s2>"/foo/0"</span><span class=w> </span><span class=err>is</span><span class=w> </span><span class=s2>"foo"</span>
</code></pre></div> </details> <h2 id=version-history>Version history<a class=headerlink href=#version-history title="Permanent link">&para;</a></h2> <ul> <li>Added in version 3.13.0.</li> </ul> <!-- https://squidfunk.github.io/mkdocs-material/reference/tooltips/#adding-a-glossary --> <aside class=md-source-file> <span class=md-source-file__fact> <span class=md-icon title="Last update"> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M21 13.1c-.1 0-.3.1-.4.2l-1 1 2.1 2.1 1-1c.2-.2.2-.6 0-.8l-1.3-1.3c-.1-.1-.2-.2-.4-.2m-1.9 1.8-6.1 6V23h2.1l6.1-6.1zM12.5 7v5.2l4 2.4-1 1L11 13V7zM11 21.9c-5.1-.5-9-4.8-9-9.9C2 6.5 6.5 2 12 2c5.3 0 9.6 4.1 10 9.3-.3-.1-.6-.2-1-.2s-.7.1-1 .2C19.6 7.2 16.2 4 12 4c-4.4 0-8 3.6-8 8 0 4.1 3.1 7.5 7.1 7.9l-.1.2z"/></svg> </span> <span class="git-revision-date-localized-plugin git-revision-date-localized-plugin-date" title="October 2, 2026 09:23:55 UTC">October 2, 2026</span> </span> </aside> </article> </div> <script>var tabs=__md_get("__tabs");if(Array.isArray(tabs))e:for(var set of document.querySelectorAll(".tabbed-set")){var labels=set.querySelector(".tabbed-labels");for(var tab of tabs)for(var label of labels.getElementsByTagName("label"))if(label.innerText.trim()===tab){var input=document.getElementById(label.htmlFor);input.checked=!0;continue e}}</script> <script>var target=document.getElementById(location.hash.slice(1));target&&target.name&&(target.checked=target.name.startsWith("__tabbed_"))</script> </div> <button type=button class="md-top md-icon" data-md-component=top hidden> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M13 20h-2V8l-5.5 5.5-1.42-1.42L12 4.16l7.92 7.92-1.42 1.42L13 8z"/></svg> Back to top </button> </main> <footer class=md-footer> <div class="md-footer-meta md-typeset"> <div class="md-footer-meta__inner md-grid"> <div class=md-copyright> <div class=md-copyright__highlight> Copyright &copy; 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</code></pre></div> </details> <h2 id=see-also>See also<a class=headerlink href=#see-also title="Permanent link">&para;</a></h2> <ul> <li><a href=../back/ >back</a> return last reference token</li> <li><a href=../pop_front/ >pop_front</a> remove the first reference token</li> <li><a href=../push_front/ >push_front</a> append an unescaped token at the start of the pointer</li> </ul> <h2 id=version-history>Version history<a class=headerlink href=#version-history title="Permanent link">&para;</a></h2> <ul> <li>Added in version 3.13.0 <span class=unreleased-version title="Not part of a release yet; the latest release is 3.12.0.">unreleased</span>.</li> </ul> <!-- https://squidfunk.github.io/mkdocs-material/reference/tooltips/#adding-a-glossary --> <aside class=md-source-file> <span class=md-source-file__fact> <span class=md-icon title="Last update"> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M21 13.1c-.1 0-.3.1-.4.2l-1 1 2.1 2.1 1-1c.2-.2.2-.6 0-.8l-1.3-1.3c-.1-.1-.2-.2-.4-.2m-1.9 1.8-6.1 6V23h2.1l6.1-6.1zM12.5 7v5.2l4 2.4-1 1L11 13V7zM11 21.9c-5.1-.5-9-4.8-9-9.9C2 6.5 6.5 2 12 2c5.3 0 9.6 4.1 10 9.3-.3-.1-.6-.2-1-.2s-.7.1-1 .2C19.6 7.2 16.2 4 12 4c-4.4 0-8 3.6-8 8 0 4.1 3.1 7.5 7.1 7.9l-.1.2z"/></svg> </span> <span class="git-revision-date-localized-plugin git-revision-date-localized-plugin-date" title="October 2, 2026 09:32:15 UTC">October 2, 2026</span> </span> </aside> </article> </div> <script>var tabs=__md_get("__tabs");if(Array.isArray(tabs))e:for(var set of document.querySelectorAll(".tabbed-set")){var labels=set.querySelector(".tabbed-labels");for(var tab of tabs)for(var label of labels.getElementsByTagName("label"))if(label.innerText.trim()===tab){var input=document.getElementById(label.htmlFor);input.checked=!0;continue e}}</script> <script>var target=document.getElementById(location.hash.slice(1));target&&target.name&&(target.checked=target.name.startsWith("__tabbed_"))</script> </div> <button type=button class="md-top md-icon" data-md-component=top hidden> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M13 20h-2V8l-5.5 5.5-1.42-1.42L12 4.16l7.92 7.92-1.42 1.42L13 8z"/></svg> Back to top </button> </main> <footer class=md-footer> <div class="md-footer-meta md-typeset"> <div class="md-footer-meta__inner md-grid"> <div class=md-copyright> <div class=md-copyright__highlight> Copyright &copy; 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+11 -1
View File
@@ -10,6 +10,10 @@ Return the first reference token.
First reference token.
## Exception safety
Strong exception safety: if an exception occurs, the original value stays intact.
## Exceptions
Throws [out_of_range.405](https://json.nlohmann.me/home/exceptions/#jsonexceptionout_of_range405) if the JSON pointer has no parent.
@@ -49,6 +53,12 @@ first reference token of "/foo" is "foo"
first reference token of "/foo/0" is "foo"
```
## See also
- [back](https://json.nlohmann.me/api/json_pointer/back/index.md) return last reference token
- [pop_front](https://json.nlohmann.me/api/json_pointer/pop_front/index.md) remove the first reference token
- [push_front](https://json.nlohmann.me/api/json_pointer/push_front/index.md) append an unescaped token at the start of the pointer
## Version history
- Added in version 3.13.0.
- Added in version 3.13.0 unreleased.
+7 -2
View File
@@ -1,3 +1,8 @@
<!doctype html><html lang=en class=no-js> <head><meta charset=utf-8><meta name=viewport content="width=device-width,initial-scale=1"><meta name=author content="Niels Lohmann"><link href="https://json.nlohmann.me/api/json_pointer/" rel="canonical"><link href=../json/ rel=prev><link href=json_pointer/ rel=next><link rel=icon href=../../assets/images/favicon.png><meta name=generator content="mkdocs-1.6.1, mkdocs-material-9.7.7"><title>Overview - JSON for Modern C++</title><link rel=stylesheet href=../../assets/stylesheets/main.ec1eaa64.min.css><link rel=stylesheet href=../../assets/stylesheets/palette.ab4e12ef.min.css><link rel="stylesheet" href="../../assets/external/fonts.googleapis.com/css.61a430c9.css"><style>:root{--md-text-font:"Roboto";--md-code-font:"JetBrains Mono"}</style><link rel=stylesheet href=../../css/custom.css><script>__md_scope=new 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<!doctype html><html lang=en class=no-js> <head><meta charset=utf-8><meta name=viewport content="width=device-width,initial-scale=1"><meta name=author content="Niels Lohmann"><link href="https://json.nlohmann.me/api/json_pointer/" rel="canonical"><link href=../json/ rel=prev><link href=json_pointer/ rel=next><link rel=icon href=../../assets/images/favicon.png><meta name=generator content="mkdocs-1.6.1, mkdocs-material-9.7.7"><title>Overview - JSON for Modern C++</title><link rel=stylesheet href=../../assets/stylesheets/main.ec1eaa64.min.css><link rel=stylesheet href=../../assets/stylesheets/palette.ab4e12ef.min.css><link rel="stylesheet" href="../../assets/external/fonts.googleapis.com/css.61a430c9.css"><style>:root{--md-text-font:"Roboto";--md-code-font:"JetBrains Mono"}</style><link rel=stylesheet href=../../css/custom.css><script>__md_scope=new 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<span class=k>class</span><span class=w> </span><span class=nc>json_pointer</span><span class=p>;</span>
</code></pre></div> <p>A <abbr title="JavaScript Object Notation">JSON</abbr> pointer defines a string syntax for identifying a specific value within a <abbr title="JavaScript Object Notation">JSON</abbr> document. It can be used with functions <a href=../basic_json/at/ ><code>at</code></a> and <a href=../basic_json/operator%5B%5D/ ><code>operator[]</code></a>. Furthermore, <abbr title="JavaScript Object Notation">JSON</abbr> pointers are the base for <abbr title="JavaScript Object Notation">JSON</abbr> patches.</p> <h2 id=template-parameters>Template parameters<a class=headerlink href=#template-parameters title="Permanent link">&para;</a></h2> <dl> <dt><code>RefStringType</code></dt> <dd>the string type used for the reference tokens making up the <abbr title="JavaScript Object Notation">JSON</abbr> pointer</dd> </dl> <div class="admonition warning"> <p class=admonition-title>Deprecation</p> <p>For backwards compatibility <code>RefStringType</code> may also be a specialization of <a href=../basic_json/ ><code>basic_json</code></a> in which case <code>string_t</code> will be deduced as <a href=../basic_json/string_t/ ><code>basic_json::string_t</code></a>. This feature is deprecated and may be removed in a future major version.</p> </div> <h2 id=member-types>Member types<a class=headerlink href=#member-types title="Permanent link">&para;</a></h2> <ul> <li><a href=string_t/ ><strong>string_t</strong></a> - the string type used for the reference tokens</li> </ul> <h2 id=member-functions>Member functions<a class=headerlink href=#member-functions title="Permanent link">&para;</a></h2> <ul> <li><a href=json_pointer/ >(constructor)</a></li> <li><a href=to_string/ ><strong>to_string</strong></a> - return a string representation of the <abbr title="JavaScript Object Notation">JSON</abbr> pointer</li> <li><a href=operator_string_t/ ><strong>operator string_t</strong></a> - return a string representation of the <abbr title="JavaScript Object Notation">JSON</abbr> pointer</li> <li><a href=operator_eq/ ><strong>operator==</strong></a> - compare: equal</li> <li><a href=operator_ne/ ><strong>operator!=</strong></a> - compare: not equal</li> <li><a href=operator_slasheq/ ><strong>operator/=</strong></a> - append to the end of the <abbr title="JavaScript Object Notation">JSON</abbr> pointer</li> <li><a href=operator_slash/ ><strong>operator/</strong></a> - create <abbr title="JavaScript Object Notation">JSON</abbr> Pointer by appending</li> <li><a href=parent_pointer/ ><strong>parent_pointer</strong></a> - returns the parent of this <abbr title="JavaScript Object Notation">JSON</abbr> pointer</li> <li><a href=pop_back/ ><strong>pop_back</strong></a> - remove the last reference token</li> <li><a href=back/ ><strong>back</strong></a> - return last reference token</li> <li><a href=push_back/ ><strong>push_back</strong></a> - append an unescaped token at the end of the pointer</li> <li><a href=pop_front/ ><strong>pop_front</strong></a> - remove the first reference token</li> <li><a href=front/ ><strong>front</strong></a> - return first reference token</li> <li><a href=push_front/ ><strong>push_front</strong></a> - append an unescaped token at the start of the pointer</li> <li><a href=empty/ ><strong>empty</strong></a> - return whether the pointer points to the root document</li> </ul> <h2 id=literals>Literals<a class=headerlink href=#literals title="Permanent link">&para;</a></h2> <ul> <li><a href=../operator_literal_json_pointer/ ><strong>operator""_json_pointer</strong></a> - user-defined string literal for <abbr title="JavaScript Object Notation">JSON</abbr> pointers</li> </ul> <h2 id=see-also>See also<a class=headerlink href=#see-also title="Permanent link">&para;</a></h2> <ul> <li><a href="https://datatracker.ietf.org/doc/html/rfc6901"><abbr title="Request for Comments">RFC</abbr> 6901</a></li> </ul> <h2 id=version-history>Version history<a class=headerlink href=#version-history title="Permanent link">&para;</a></h2> <ul> <li>Added in version 2.0.0.</li> <li>Changed template parameter from <code>basic_json</code> to string type in version 3.11.0.</li> </ul> <!-- https://squidfunk.github.io/mkdocs-material/reference/tooltips/#adding-a-glossary --> <aside class=md-source-file> <span class=md-source-file__fact> <span class=md-icon title="Last update"> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M21 13.1c-.1 0-.3.1-.4.2l-1 1 2.1 2.1 1-1c.2-.2.2-.6 0-.8l-1.3-1.3c-.1-.1-.2-.2-.4-.2m-1.9 1.8-6.1 6V23h2.1l6.1-6.1zM12.5 7v5.2l4 2.4-1 1L11 13V7zM11 21.9c-5.1-.5-9-4.8-9-9.9C2 6.5 6.5 2 12 2c5.3 0 9.6 4.1 10 9.3-.3-.1-.6-.2-1-.2s-.7.1-1 .2C19.6 7.2 16.2 4 12 4c-4.4 0-8 3.6-8 8 0 4.1 3.1 7.5 7.1 7.9l-.1.2z"/></svg> </span> <span class="git-revision-date-localized-plugin git-revision-date-localized-plugin-date" title="October 2, 2026 09:23:55 UTC">October 2, 2026</span> </span> </aside> </article> </div> <script>var tabs=__md_get("__tabs");if(Array.isArray(tabs))e:for(var set of document.querySelectorAll(".tabbedLine truncated
</code></pre></div> <p>A <abbr title="JavaScript Object Notation">JSON</abbr> pointer defines a string syntax for identifying a specific value within a <abbr title="JavaScript Object Notation">JSON</abbr> document. It can be used with functions <a href=../basic_json/at/ ><code>at</code></a> and <a href=../basic_json/operator%5B%5D/ ><code>operator[]</code></a>. Furthermore, <abbr title="JavaScript Object Notation">JSON</abbr> pointers are the base for <abbr title="JavaScript Object Notation">JSON</abbr> patches.</p> <h2 id=template-parameters>Template parameters<a class=headerlink href=#template-parameters title="Permanent link">&para;</a></h2> <dl> <dt><code>RefStringType</code></dt> <dd>the string type used for the reference tokens making up the <abbr title="JavaScript Object Notation">JSON</abbr> pointer</dd> </dl> <div class="admonition warning"> <p class=admonition-title>Deprecation</p> <p>For backwards compatibility <code>RefStringType</code> may also be a specialization of <a href=../basic_json/ ><code>basic_json</code></a> in which case <code>string_t</code> will be deduced as <a href=../basic_json/string_t/ ><code>basic_json::string_t</code></a>. This feature is deprecated and may be removed in a future major version.</p> <p>See the <a href=../../integration/migration_guide/#json-pointers>migration guide</a> for how to update existing code.</p> </div> <p>A <abbr title="JavaScript Object Notation">JSON</abbr> pointer is internally a sequence of reference tokens. <a href=front/ ><code>front</code></a>, <a href=pop_front/ ><code>pop_front</code></a>, and <a href=push_front/ ><code>push_front</code></a> act on the first reference token, whereas <a href=back/ ><code>back</code></a>, <a href=pop_back/ ><code>pop_back</code></a>, and <a href=push_back/ ><code>push_back</code></a> act on the last one. <a href=parent_pointer/ ><code>parent_pointer</code></a> returns a new <abbr title="JavaScript Object Notation">JSON</abbr> pointer with the last reference token removed (like a non-mutating <a href=pop_back/ ><code>pop_back</code></a>):</p> <pre class=mermaid><code>flowchart LR
A["a"] --&gt; B["b"] --&gt; C["c"]
front["front() / pop_front() / push_front()"] -.-&gt; A
back["back() / pop_back() / push_back()"] -.-&gt; C
parent["parent_pointer() returns /a/b"] -.-&gt; B</code></pre> <p>The diagram shows the reference tokens of the <abbr title="JavaScript Object Notation">JSON</abbr> pointer <code>/a/b/c</code>.</p> <h2 id=member-types>Member types<a class=headerlink href=#member-types title="Permanent link">&para;</a></h2> <ul> <li><a href=string_t/ ><strong>string_t</strong></a> - the string type used for the reference tokens</li> </ul> <h2 id=member-functions>Member functions<a class=headerlink href=#member-functions title="Permanent link">&para;</a></h2> <ul> <li><a href=json_pointer/ >(constructor)</a></li> <li><a href=to_string/ ><strong>to_string</strong></a> - return a string representation of the <abbr title="JavaScript Object Notation">JSON</abbr> pointer</li> <li><a href=operator_string_t/ ><strong>operator string_t</strong></a> - return a string representation of the <abbr title="JavaScript Object Notation">JSON</abbr> pointer (deprecated)</li> <li><a href=operator_eq/ ><strong>operator==</strong></a> - compare: equal</li> <li><a href=operator_ne/ ><strong>operator!=</strong></a> - compare: not equal</li> <li><a href=operator_spaceship/ ><strong>operator&lt;=&gt;</strong></a> - compare: 3-way (C++20)</li> <li><a href=operator_slasheq/ ><strong>operator/=</strong></a> - append to the end of the <abbr title="JavaScript Object Notation">JSON</abbr> pointer</li> <li><a href=operator_slash/ ><strong>operator/</strong></a> - create <abbr title="JavaScript Object Notation">JSON</abbr> Pointer by appending</li> <li><a href=parent_pointer/ ><strong>parent_pointer</strong></a> - returns the parent of this <abbr title="JavaScript Object Notation">JSON</abbr> pointer</li> <li><a href=pop_back/ ><strong>pop_back</strong></a> - remove the last reference token</li> <li><a href=back/ ><strong>back</strong></a> - return last reference token</li> <li><a href=push_back/ ><strong>push_back</strong></a> - append an unescaped token at the end of the pointer</li> <li><a href=pop_front/ ><strong>pop_front</strong></a> - remove the first reference token</li> <li><a href=front/ ><strong>front</strong></a> - return first reference token</li> <li><a href=push_front/ ><strong>push_front</strong></a> - append an unescaped token at the start of the pointer</li> <li><a href=empty/ ><strong>empty</strong></a> - return whether the pointer points to the root document</li> </ul> <h2 id=literals>Literals<a class=headerlink href=#literals title="Permanent link">&para;</a></h2> <ul> <li><a href=../operator_literal_json_pointer/ ><strong>operator""_json_pointer</strong></a> - user-defined string literal for <abbr title="JavaScript Object Notation">JSON</abbr> pointers</li> </ul> <h2 id=see-also>See also<a class=headerlink href=#see-also title="Permanent link">&para;</a></h2> <ul> <li><a href="https://datatracker.ietf.org/doc/html/rfc6901"><abbr title="Request for Comments">RFC</abbr> 6901</a></li> </ul> <h2 id=version-history>Version history<a class=headerlink href=#version-history title="Permanent link">&para;</a></h2> <ul> <li>Added in version 2.0.0.</li> <li>Changed template parameter from <code>basic_json</code> to string type in version 3.11.0.</li> </ul> <!-- https://squidfunk.github.io/mkdocs-material/reference/tooltips/#adding-a-glossary --> <aside class=md-source-file> <span class=md-source-file__fact> <span class=md-icon title="Last update"> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M21 13.1c-.1 0-.3.1-.4.2l-1 1 2.1 2.1 1-1c.2-.2.2-.6 0-.8l-1.3-1.3c-.1-.1-.2-.2-.4-.2m-1.9 1.8-6.1 6V23h2.1l6.1-6.1zM12.5 7v5.2l4 2.4-1 1L11 13V7zM11 21.9c-5.1-.5-9-4.8-9-9.9C2 6.5 6.5 2 12 2c5.3 0 9.6 4.1 10 9.3-.3-.1-.6-.2-1-.2s-.7.1-1 .2C19.6 7.2 16.2 4 12 4c-4.4 0-8 3.6-8 8 0 4.1 3.1 7.5 7.1 7.9l-.1.2z"/></svg> </span> <span class="git-revision-date-localized-plugin git-revision-date-localized-plugin-date" title="October 2, 2026 09:32:15 UTC">October 2, 2026</span> </span> </aside> </article> </div> <script>var tabs=__md_get("__tabs");if(Array.isArray(tabs))e:for(var set of document.querySelectorAll(".tabbed-set")){var labels=set.querySelector(".tabbed-labels");for(var tab of tabs)for(var label of labels.getElementsByTagName("label"))if(label.innerText.trim()===tab){var input=document.getElementById(label.htmlFor);input.checked=!0;continue e}}</script> <script>var target=document.getElementById(location.hash.slice(1));target&&target.name&&(target.checked=target.name.startsWith("__tabbed_"))</script> </div> <button type=button class="md-top md-icon" data-md-component=top hidden> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M13 20h-2V8l-5.5 5.5-1.42-1.42L12 4.16l7.92 7.92-1.42 1.42L13 8z"/></svg> Back to top </button> </main> <footer class=md-footer> <div class="md-footer-meta md-typeset"> <div class="md-footer-meta__inner md-grid"> <div class=md-copyright> <div class=md-copyright__highlight> Copyright &copy; 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@@ -15,6 +15,21 @@ Deprecation
For backwards compatibility `RefStringType` may also be a specialization of [`basic_json`](https://json.nlohmann.me/api/basic_json/index.md) in which case `string_t` will be deduced as [`basic_json::string_t`](https://json.nlohmann.me/api/basic_json/string_t/index.md). This feature is deprecated and may be removed in a future major version.
See the [migration guide](https://json.nlohmann.me/integration/migration_guide/#json-pointers) for how to update existing code.
A JSON pointer is internally a sequence of reference tokens. [`front`](https://json.nlohmann.me/api/json_pointer/front/index.md), [`pop_front`](https://json.nlohmann.me/api/json_pointer/pop_front/index.md), and [`push_front`](https://json.nlohmann.me/api/json_pointer/push_front/index.md) act on the first reference token, whereas [`back`](https://json.nlohmann.me/api/json_pointer/back/index.md), [`pop_back`](https://json.nlohmann.me/api/json_pointer/pop_back/index.md), and [`push_back`](https://json.nlohmann.me/api/json_pointer/push_back/index.md) act on the last one. [`parent_pointer`](https://json.nlohmann.me/api/json_pointer/parent_pointer/index.md) returns a new JSON pointer with the last reference token removed (like a non-mutating [`pop_back`](https://json.nlohmann.me/api/json_pointer/pop_back/index.md)):
```
flowchart LR
A["a"] --> B["b"] --> C["c"]
front["front() / pop_front() / push_front()"] -.-> A
back["back() / pop_back() / push_back()"] -.-> C
parent["parent_pointer() returns /a/b"] -.-> B
```
The diagram shows the reference tokens of the JSON pointer `/a/b/c`.
## Member types
- [**string_t**](https://json.nlohmann.me/api/json_pointer/string_t/index.md) - the string type used for the reference tokens
@@ -23,9 +38,10 @@ For backwards compatibility `RefStringType` may also be a specialization of [`ba
- [(constructor)](https://json.nlohmann.me/api/json_pointer/json_pointer/index.md)
- [**to_string**](https://json.nlohmann.me/api/json_pointer/to_string/index.md) - return a string representation of the JSON pointer
- [**operator string_t**](https://json.nlohmann.me/api/json_pointer/operator_string_t/index.md) - return a string representation of the JSON pointer
- [**operator string_t**](https://json.nlohmann.me/api/json_pointer/operator_string_t/index.md) - return a string representation of the JSON pointer (deprecated)
- [**operator==**](https://json.nlohmann.me/api/json_pointer/operator_eq/index.md) - compare: equal
- [**operator!=**](https://json.nlohmann.me/api/json_pointer/operator_ne/index.md) - compare: not equal
- [**operator\<=>**](https://json.nlohmann.me/api/json_pointer/operator_spaceship/index.md) - compare: 3-way (C++20)
- [**operator/=**](https://json.nlohmann.me/api/json_pointer/operator_slasheq/index.md) - append to the end of the JSON pointer
- [**operator/**](https://json.nlohmann.me/api/json_pointer/operator_slash/index.md) - create JSON Pointer by appending
- [**parent_pointer**](https://json.nlohmann.me/api/json_pointer/parent_pointer/index.md) - returns the parent of this JSON pointer
+13
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@@ -12,6 +12,10 @@ Create a JSON pointer according to the syntax described in
`s` (in)
: string representing the JSON pointer; if omitted, the empty string is assumed which references the whole JSON value
## Exception safety
Strong guarantee: if an exception is thrown, there are no changes to any JSON pointer.
## Exceptions
- Throws [parse_error.107](../../home/exceptions.md#jsonexceptionparse_error107) if the given JSON pointer `s` is
@@ -19,6 +23,10 @@ Create a JSON pointer according to the syntax described in
- Throws [parse_error.108](../../home/exceptions.md#jsonexceptionparse_error108) if a tilde (`~`) in the given JSON
pointer `s` is not followed by `0` (representing `~`) or `1` (representing `/`); see example below.
## Complexity
Linear in the length of `s`.
## Examples
??? example
@@ -35,6 +43,11 @@ Create a JSON pointer according to the syntax described in
--8<-- "examples/json_pointer.output"
```
## See also
- [JSON Pointer](../../features/json_pointer.md) - the article on JSON Pointer support
- [operator""_json_pointer](../operator_literal_json_pointer.md) user-defined string literal for JSON pointers
## Version history
- Added in version 2.0.0.
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@@ -1,5 +1,5 @@
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</code></pre></div> <p>Create a <abbr title="JavaScript Object Notation">JSON</abbr> pointer according to the syntax described in <a href="https://tools.ietf.org/html/rfc6901#section-3">Section 3 of RFC6901</a>.</p> <h2 id=parameters>Parameters<a class=headerlink href=#parameters title="Permanent link">&para;</a></h2> <dl> <dt><code>s</code> (in)</dt> <dd>string representing the <abbr title="JavaScript Object Notation">JSON</abbr> pointer; if omitted, the empty string is assumed which references the whole <abbr title="JavaScript Object Notation">JSON</abbr> value</dd> </dl> <h2 id=exceptions>Exceptions<a class=headerlink href=#exceptions title="Permanent link">&para;</a></h2> <ul> <li>Throws <a href=../../../home/exceptions/#jsonexceptionparse_error107>parse_error.107</a> if the given <abbr title="JavaScript Object Notation">JSON</abbr> pointer <code>s</code> is nonempty and does not begin with a slash (<code>/</code>); see example below.</li> <li>Throws <a href=../../../home/exceptions/#jsonexceptionparse_error108>parse_error.108</a> if a tilde (<code>~</code>) in the given <abbr title="JavaScript Object Notation">JSON</abbr> pointer <code>s</code> is not followed by <code>0</code> (representing <code>~</code>) or <code>1</code> (representing <code>/</code>); see example below.</li> </ul> <h2 id=examples>Examples<a class=headerlink href=#examples title="Permanent link">&para;</a></h2> <details class=example> <summary>Example</summary> <p>The example shows the construction several valid <abbr title="JavaScript Object Notation">JSON</abbr> pointers as well as the exceptional behavior.</p> <div class=highlight><pre><span></span><code><span class=cp>#include</span><span class=w> </span><span class=cpf>&lt;iostream&gt;</span>
<!doctype html><html lang=en class=no-js> <head><meta charset=utf-8><meta name=viewport content="width=device-width,initial-scale=1"><meta name=author content="Niels Lohmann"><link href="https://json.nlohmann.me/api/json_pointer/json_pointer/" rel="canonical"><link href=../ rel=prev><link href=../back/ rel=next><link rel=icon href=../../../assets/images/favicon.png><meta name=generator content="mkdocs-1.6.1, mkdocs-material-9.7.7"><title>(Constructor) - JSON for Modern C++</title><link rel=stylesheet href=../../../assets/stylesheets/main.ec1eaa64.min.css><link rel=stylesheet href=../../../assets/stylesheets/palette.ab4e12ef.min.css><link rel="stylesheet" href="../../../assets/external/fonts.googleapis.com/css.61a430c9.css"><style>:root{--md-text-font:"Roboto";--md-code-font:"JetBrains Mono"}</style><link rel=stylesheet href=../../../css/custom.css><script>__md_scope=new URL("../../..",location),__md_hash=e=>[...e].reduce(((e,_)=>(e<<5)-e+_.charCodeAt(0)),0),__md_get=(e,_=localStorage,t=__md_scope)=>JSON.parse(_.getItem(t.pathname+"."+e)),__md_set=(e,_,t=localStorage,a=__md_scope)=>{try{t.setItem(a.pathname+"."+e,JSON.stringify(_))}catch(e){}}</script></head> <body dir=ltr data-md-color-scheme=default data-md-color-primary=indigo data-md-color-accent=indigo> <input class=md-toggle data-md-toggle=drawer type=checkbox id=__drawer autocomplete=off> <input class=md-toggle data-md-toggle=search type=checkbox id=__search autocomplete=off> <label class=md-overlay for=__drawer></label> <div data-md-component=skip> <a href=#nlohmannjson_pointerjson_pointer class=md-skip> Skip to content </a> </div> <div data-md-component=announce> </div> <header class=md-header data-md-component=header> <nav class="md-header__inner md-grid" aria-label=Header> <a href=../../.. title="JSON for Modern C++" class="md-header__button md-logo" aria-label="JSON for Modern C++" data-md-component=logo> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M12 8a3 3 0 0 0 3-3 3 3 0 0 0-3-3 3 3 0 0 0-3 3 3 3 0 0 0 3 3m0 3.54C9.64 9.35 6.5 8 3 8v11c3.5 0 6.64 1.35 9 3.54 2.36-2.19 5.5-3.54 9-3.54V8c-3.5 0-6.64 1.35-9 3.54"/></svg> </a> <label class="md-header__button md-icon" for=__drawer> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M3 6h18v2H3zm0 5h18v2H3zm0 5h18v2H3z"/></svg> </label> <div class=md-header__title data-md-component=header-title> <div class=md-header__ellipsis> <div class=md-header__topic> <span class=md-ellipsis> JSON for Modern C++ </span> </div> <div class=md-header__topic data-md-component=header-topic> <span class=md-ellipsis> (Constructor) </span> </div> </div> </div> <form class=md-header__option data-md-component=palette> <input class=md-option data-md-color-media="(prefers-color-scheme: light)" data-md-color-scheme=default data-md-color-primary=indigo data-md-color-accent=indigo aria-label="Switch to 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</code></pre></div> <p>Create a <abbr title="JavaScript Object Notation">JSON</abbr> pointer according to the syntax described in <a href="https://tools.ietf.org/html/rfc6901#section-3">Section 3 of RFC6901</a>.</p> <h2 id=parameters>Parameters<a class=headerlink href=#parameters title="Permanent link">&para;</a></h2> <dl> <dt><code>s</code> (in)</dt> <dd>string representing the <abbr title="JavaScript Object Notation">JSON</abbr> pointer; if omitted, the empty string is assumed which references the whole <abbr title="JavaScript Object Notation">JSON</abbr> value</dd> </dl> <h2 id=exception-safety>Exception safety<a class=headerlink href=#exception-safety title="Permanent link">&para;</a></h2> <p>Strong guarantee: if an exception is thrown, there are no changes to any <abbr title="JavaScript Object Notation">JSON</abbr> pointer.</p> <h2 id=exceptions>Exceptions<a class=headerlink href=#exceptions title="Permanent link">&para;</a></h2> <ul> <li>Throws <a href=../../../home/exceptions/#jsonexceptionparse_error107>parse_error.107</a> if the given <abbr title="JavaScript Object Notation">JSON</abbr> pointer <code>s</code> is nonempty and does not begin with a slash (<code>/</code>); see example below.</li> <li>Throws <a href=../../../home/exceptions/#jsonexceptionparse_error108>parse_error.108</a> if a tilde (<code>~</code>) in the given <abbr title="JavaScript Object Notation">JSON</abbr> pointer <code>s</code> is not followed by <code>0</code> (representing <code>~</code>) or <code>1</code> (representing <code>/</code>); see example below.</li> </ul> <h2 id=complexity>Complexity<a class=headerlink href=#complexity title="Permanent link">&para;</a></h2> <p>Linear in the length of <code>s</code>.</p> <h2 id=examples>Examples<a class=headerlink href=#examples title="Permanent link">&para;</a></h2> <details class=example> <summary>Example</summary> <p>The example shows the construction several valid <abbr title="JavaScript Object Notation">JSON</abbr> pointers as well as the exceptional behavior.</p> <div class=highlight><pre><span></span><code><span class=cp>#include</span><span class=w> </span><span class=cpf>&lt;iostream&gt;</span>
<span class=cp>#include</span><span class=w> </span><span class=cpf>&lt;nlohmann/json.hpp&gt;</span>
<span class=k>using</span><span class=w> </span><span class=n>json</span><span class=w> </span><span class=o>=</span><span class=w> </span><span class=n>nlohmann</span><span class=o>::</span><span class=n>json</span><span class=p>;</span>
@@ -49,4 +49,4 @@
</code></pre></div> <p>Output:</p> <div class=highlight><pre><span></span><code><span class=p>[</span><span class=err>jso</span><span class=kc>n</span><span class=err>.excep</span><span class=kc>t</span><span class=err>io</span><span class=kc>n</span><span class=err>.parse_error.</span><span class=mi>107</span><span class=p>]</span><span class=w> </span><span class=err>parse</span><span class=w> </span><span class=err>error</span><span class=w> </span><span class=err>a</span><span class=kc>t</span><span class=w> </span><span class=err>by</span><span class=kc>te</span><span class=w> </span><span class=mi>1</span><span class=p>:</span><span class=w> </span><span class=err>JSON</span><span class=w> </span><span class=err>poi</span><span class=kc>nter</span><span class=w> </span><span class=err>mus</span><span class=kc>t</span><span class=w> </span><span class=err>be</span><span class=w> </span><span class=err>emp</span><span class=kc>t</span><span class=err>y</span><span class=w> </span><span class=err>or</span><span class=w> </span><span class=err>begi</span><span class=kc>n</span><span class=w> </span><span class=err>wi</span><span class=kc>t</span><span class=err>h</span><span class=w> </span><span class=err>'/'</span><span class=w> </span><span class=mi>-</span><span class=w> </span><span class=err>was</span><span class=p>:</span><span class=w> </span><span class=err>'</span><span class=kc>f</span><span class=err>oo'</span>
<span class=p>[</span><span class=err>jso</span><span class=kc>n</span><span class=err>.excep</span><span class=kc>t</span><span class=err>io</span><span class=kc>n</span><span class=err>.parse_error.</span><span class=mi>108</span><span class=p>]</span><span class=w> </span><span class=err>parse</span><span class=w> </span><span class=err>error</span><span class=p>:</span><span class=w> </span><span class=err>escape</span><span class=w> </span><span class=err>charac</span><span class=kc>ter</span><span class=w> </span><span class=err>'~'</span><span class=w> </span><span class=err>mus</span><span class=kc>t</span><span class=w> </span><span class=err>be</span><span class=w> </span><span class=kc>f</span><span class=err>ollowed</span><span class=w> </span><span class=err>wi</span><span class=kc>t</span><span class=err>h</span><span class=w> </span><span class=err>'</span><span class=mi>0</span><span class=err>'</span><span class=w> </span><span class=err>or</span><span class=w> </span><span class=err>'</span><span class=mi>1</span><span class=err>'</span>
<span class=p>[</span><span class=err>jso</span><span class=kc>n</span><span class=err>.excep</span><span class=kc>t</span><span class=err>io</span><span class=kc>n</span><span class=err>.parse_error.</span><span class=mi>108</span><span class=p>]</span><span class=w> </span><span class=err>parse</span><span class=w> </span><span class=err>error</span><span class=p>:</span><span class=w> </span><span class=err>escape</span><span class=w> </span><span class=err>charac</span><span class=kc>ter</span><span class=w> </span><span class=err>'~'</span><span class=w> </span><span class=err>mus</span><span class=kc>t</span><span class=w> </span><span class=err>be</span><span class=w> </span><span class=kc>f</span><span class=err>ollowed</span><span class=w> </span><span class=err>wi</span><span class=kc>t</span><span class=err>h</span><span class=w> </span><span class=err>'</span><span class=mi>0</span><span class=err>'</span><span class=w> </span><span class=err>or</span><span class=w> </span><span class=err>'</span><span class=mi>1</span><span class=err>'</span>
</code></pre></div> </details> <h2 id=version-history>Version history<a class=headerlink href=#version-history title="Permanent link">&para;</a></h2> <ul> <li>Added in version 2.0.0.</li> <li>Changed type of <code>s</code> to <code>string_t</code> in version 3.11.0.</li> </ul> <!-- https://squidfunk.github.io/mkdocs-material/reference/tooltips/#adding-a-glossary --> <aside class=md-source-file> <span class=md-source-file__fact> <span class=md-icon title="Last update"> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M21 13.1c-.1 0-.3.1-.4.2l-1 1 2.1 2.1 1-1c.2-.2.2-.6 0-.8l-1.3-1.3c-.1-.1-.2-.2-.4-.2m-1.9 1.8-6.1 6V23h2.1l6.1-6.1zM12.5 7v5.2l4 2.4-1 1L11 13V7zM11 21.9c-5.1-.5-9-4.8-9-9.9C2 6.5 6.5 2 12 2c5.3 0 9.6 4.1 10 9.3-.3-.1-.6-.2-1-.2s-.7.1-1 .2C19.6 7.2 16.2 4 12 4c-4.4 0-8 3.6-8 8 0 4.1 3.1 7.5 7.1 7.9l-.1.2z"/></svg> </span> <span class="git-revision-date-localized-plugin git-revision-date-localized-plugin-date" title="October 2, 2026 09:23:55 UTC">October 2, 2026</span> </span> </aside> </article> </div> <script>var tabs=__md_get("__tabs");if(Array.isArray(tabs))e:for(var set of document.querySelectorAll(".tabbed-set")){var labels=set.querySelector(".tabbed-labels");for(var tab of tabs)for(var label of labels.getElementsByTagName("label"))if(label.innerText.trim()===tab){var input=document.getElementById(label.htmlFor);input.checked=!0;continue e}}</script> <script>var target=document.getElementById(location.hash.slice(1));target&&target.name&&(target.checked=target.name.startsWith("__tabbed_"))</script> </div> <button type=button class="md-top md-icon" data-md-component=top hidden> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M13 20h-2V8l-5.5 5.5-1.42-1.42L12 4.16l7.92 7.92-1.42 1.42L13 8z"/></svg> Back to top </button> </main> <footer class=md-footer> <div class="md-footer-meta md-typeset"> <div class="md-footer-meta__inner md-grid"> <div class=md-copyright> <div class=md-copyright__highlight> Copyright &copy; 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</code></pre></div> </details> <h2 id=see-also>See also<a class=headerlink href=#see-also title="Permanent link">&para;</a></h2> <ul> <li><a href=../../../features/json_pointer/ ><abbr title="JavaScript Object Notation">JSON</abbr> Pointer</a> - the article on <abbr title="JavaScript Object Notation">JSON</abbr> Pointer support</li> <li><a href=../../operator_literal_json_pointer/ >operator""_json_pointer</a> user-defined string literal for <abbr title="JavaScript Object Notation">JSON</abbr> pointers</li> </ul> <h2 id=version-history>Version history<a class=headerlink href=#version-history title="Permanent link">&para;</a></h2> <ul> <li>Added in version 2.0.0.</li> <li>Changed type of <code>s</code> to <code>string_t</code> in version 3.11.0.</li> </ul> <!-- https://squidfunk.github.io/mkdocs-material/reference/tooltips/#adding-a-glossary --> <aside class=md-source-file> <span class=md-source-file__fact> <span class=md-icon title="Last update"> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M21 13.1c-.1 0-.3.1-.4.2l-1 1 2.1 2.1 1-1c.2-.2.2-.6 0-.8l-1.3-1.3c-.1-.1-.2-.2-.4-.2m-1.9 1.8-6.1 6V23h2.1l6.1-6.1zM12.5 7v5.2l4 2.4-1 1L11 13V7zM11 21.9c-5.1-.5-9-4.8-9-9.9C2 6.5 6.5 2 12 2c5.3 0 9.6 4.1 10 9.3-.3-.1-.6-.2-1-.2s-.7.1-1 .2C19.6 7.2 16.2 4 12 4c-4.4 0-8 3.6-8 8 0 4.1 3.1 7.5 7.1 7.9l-.1.2z"/></svg> </span> <span class="git-revision-date-localized-plugin git-revision-date-localized-plugin-date" title="October 2, 2026 09:32:15 UTC">October 2, 2026</span> </span> </aside> </article> </div> <script>var tabs=__md_get("__tabs");if(Array.isArray(tabs))e:for(var set of document.querySelectorAll(".tabbed-set")){var labels=set.querySelector(".tabbed-labels");for(var tab of tabs)for(var label of labels.getElementsByTagName("label"))if(label.innerText.trim()===tab){var input=document.getElementById(label.htmlFor);input.checked=!0;continue e}}</script> <script>var target=document.getElementById(location.hash.slice(1));target&&target.name&&(target.checked=target.name.startsWith("__tabbed_"))</script> </div> <button type=button class="md-top md-icon" data-md-component=top hidden> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M13 20h-2V8l-5.5 5.5-1.42-1.42L12 4.16l7.92 7.92-1.42 1.42L13 8z"/></svg> Back to top </button> </main> <footer class=md-footer> <div class="md-footer-meta md-typeset"> <div class="md-footer-meta__inner md-grid"> <div class=md-copyright> <div class=md-copyright__highlight> Copyright &copy; 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+13
View File
@@ -10,11 +10,19 @@ Create a JSON pointer according to the syntax described in [Section 3 of RFC6901
`s` (in) : string representing the JSON pointer; if omitted, the empty string is assumed which references the whole JSON value
## Exception safety
Strong guarantee: if an exception is thrown, there are no changes to any JSON pointer.
## Exceptions
- Throws [parse_error.107](https://json.nlohmann.me/home/exceptions/#jsonexceptionparse_error107) if the given JSON pointer `s` is nonempty and does not begin with a slash (`/`); see example below.
- Throws [parse_error.108](https://json.nlohmann.me/home/exceptions/#jsonexceptionparse_error108) if a tilde (`~`) in the given JSON pointer `s` is not followed by `0` (representing `~`) or `1` (representing `/`); see example below.
## Complexity
Linear in the length of `s`.
## Examples
Example
@@ -79,6 +87,11 @@ Output:
[json.exception.parse_error.108] parse error: escape character '~' must be followed with '0' or '1'
```
## See also
- [JSON Pointer](https://json.nlohmann.me/features/json_pointer/index.md) - the article on JSON Pointer support
- [operator""\_json_pointer](https://json.nlohmann.me/api/operator_literal_json_pointer/index.md) user-defined string literal for JSON pointers
## Version history
- Added in version 2.0.0.
+7
View File
@@ -77,6 +77,8 @@ tokens.
Overload 2 is deprecated and will be removed in a future major version release.
See the [migration guide](../../integration/migration_guide.md#json-pointers) for how to update existing code.
## Examples
??? example "Example: (1) Comparing JSON pointers"
@@ -107,6 +109,11 @@ tokens.
--8<-- "examples/json_pointer__operator__equal_stringtype.output"
```
## See also
- [operator!=](operator_ne.md) compare for inequality
- [operator<=>](operator_spaceship.md) comparison: 3-way (C++20)
## Version history
1. Added in version 2.1.0. Added C++20 member functions in version 3.11.2.
+3 -3
View File
@@ -1,4 +1,4 @@
<!doctype html><html lang=en class=no-js> <head><meta charset=utf-8><meta name=viewport content="width=device-width,initial-scale=1"><meta name=author content="Niels Lohmann"><link href="https://json.nlohmann.me/api/json_pointer/operator_eq/" rel="canonical"><link href=../operator_string_t/ rel=prev><link href=../operator_ne/ rel=next><link rel=icon href=../../../assets/images/favicon.png><meta name=generator content="mkdocs-1.6.1, mkdocs-material-9.7.7"><title>operator== - JSON for Modern C++</title><link rel=stylesheet href=../../../assets/stylesheets/main.ec1eaa64.min.css><link rel=stylesheet href=../../../assets/stylesheets/palette.ab4e12ef.min.css><link rel="stylesheet" href="../../../assets/external/fonts.googleapis.com/css.61a430c9.css"><style>:root{--md-text-font:"Roboto";--md-code-font:"JetBrains Mono"}</style><link rel=stylesheet href=../../../css/custom.css><script>__md_scope=new 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<span class=k>template</span><span class=o>&lt;</span><span class=k>typename</span><span class=w> </span><span class=nc>RefStringTypeLhs</span><span class=p>,</span><span class=w> </span><span class=k>typename</span><span class=w> </span><span class=nc>RefStringTypeRhs</span><span class=o>&gt;</span>
<span class=kt>bool</span><span class=w> </span><span class=k>operator</span><span class=o>==</span><span class=p>(</span>
<span class=w> </span><span class=k>const</span><span class=w> </span><span class=n>json_pointer</span><span class=o>&lt;</span><span class=n>RefStringTypeLhs</span><span class=o>&gt;&amp;</span><span class=w> </span><span class=n>lhs</span><span class=p>,</span>
@@ -22,7 +22,7 @@
<span class=w> </span><span class=kt>bool</span><span class=w> </span><span class=k>operator</span><span class=o>==</span><span class=p>(</span><span class=k>const</span><span class=w> </span><span class=n>string_t</span><span class=o>&amp;</span><span class=w> </span><span class=n>rhs</span><span class=p>)</span><span class=w> </span><span class=k>const</span><span class=p>;</span><span class=w> </span><span class=c1>// (2)</span>
<span class=p>};</span>
</code></pre></div> <ol> <li> <p>Compares two <abbr title="JavaScript Object Notation">JSON</abbr> pointers for equality by comparing their reference tokens.</p> </li> <li> <p>Compares a <abbr title="JavaScript Object Notation">JSON</abbr> pointer and a string or a string and a <abbr title="JavaScript Object Notation">JSON</abbr> pointer for equality by converting the string to a <abbr title="JavaScript Object Notation">JSON</abbr> pointer and comparing the <abbr title="JavaScript Object Notation">JSON</abbr> pointers according to 1.</p> </li> </ol> <h2 id=template-parameters>Template parameters<a class=headerlink href=#template-parameters title="Permanent link">&para;</a></h2> <dl> <dt><code>RefStringTypeLhs</code>, <code>RefStringTypeRhs</code></dt> <dd>the string type of the left-hand side or right-hand side <abbr title="JavaScript Object Notation">JSON</abbr> pointer, respectively</dd> <dt><code>StringType</code></dt> <dd>the string type derived from the <code>json_pointer</code> operand (<a href=../string_t/ ><code>json_pointer::string_t</code></a>)</dd> </dl> <h2 id=parameters>Parameters<a class=headerlink href=#parameters title="Permanent link">&para;</a></h2> <dl> <dt><code>lhs</code> (in)</dt> <dd>first value to consider</dd> <dt><code>rhs</code> (in)</dt> <dd>second value to consider</dd> </dl> <h2 id=return-value>Return value<a class=headerlink href=#return-value title="Permanent link">&para;</a></h2> <p>whether the values <code>lhs</code>/<code>*this</code> and <code>rhs</code> are equal</p> <h2 id=exception-safety>Exception safety<a class=headerlink href=#exception-safety title="Permanent link">&para;</a></h2> <ol> <li>No-throw guarantee: this function never throws exceptions.</li> <li>Strong exception safety: if an exception occurs, the original value stays intact.</li> </ol> <h2 id=exceptions>Exceptions<a class=headerlink href=#exceptions title="Permanent link">&para;</a></h2> <ol> <li>(none)</li> <li>The function can throw the following exceptions:</li> <li>Throws <a href=../../../home/exceptions/#jsonexceptionparse_error107>parse_error.107</a> if the given <abbr title="JavaScript Object Notation">JSON</abbr> pointer <code>s</code> is nonempty and does not begin with a slash (<code>/</code>); see example below.</li> <li>Throws <a href=../../../home/exceptions/#jsonexceptionparse_error108>parse_error.108</a> if a tilde (<code>~</code>) in the given <abbr title="JavaScript Object Notation">JSON</abbr> pointer <code>s</code> is not followed by <code>0</code> (representing <code>~</code>) or <code>1</code> (representing <code>/</code>); see example below.</li> </ol> <h2 id=complexity>Complexity<a class=headerlink href=#complexity title="Permanent link">&para;</a></h2> <p>Constant if <code>lhs</code> and <code>rhs</code> differ in the number of reference tokens, otherwise linear in the number of reference tokens.</p> <h2 id=notes>Notes<a class=headerlink href=#notes title="Permanent link">&para;</a></h2> <div class="admonition warning"> <p class=admonition-title>Deprecation</p> <p>Overload 2 is deprecated and will be removed in a future major version release.</p> </div> <h2 id=examples>Examples<a class=headerlink href=#examples title="Permanent link">&para;</a></h2> <details class=example> <summary>Example: (1) Comparing <abbr title="JavaScript Object Notation">JSON</abbr> pointers</summary> <p>The example demonstrates comparing <abbr title="JavaScript Object Notation">JSON</abbr> pointers.</p> <div class=highlight><pre><span></span><code><span class=cp>#include</span><span class=w> </span><span class=cpf>&lt;iostream&gt;</span>
</code></pre></div> <ol> <li> <p>Compares two <abbr title="JavaScript Object Notation">JSON</abbr> pointers for equality by comparing their reference tokens.</p> </li> <li> <p>Compares a <abbr title="JavaScript Object Notation">JSON</abbr> pointer and a string or a string and a <abbr title="JavaScript Object Notation">JSON</abbr> pointer for equality by converting the string to a <abbr title="JavaScript Object Notation">JSON</abbr> pointer and comparing the <abbr title="JavaScript Object Notation">JSON</abbr> pointers according to 1.</p> </li> </ol> <h2 id=template-parameters>Template parameters<a class=headerlink href=#template-parameters title="Permanent link">&para;</a></h2> <dl> <dt><code>RefStringTypeLhs</code>, <code>RefStringTypeRhs</code></dt> <dd>the string type of the left-hand side or right-hand side <abbr title="JavaScript Object Notation">JSON</abbr> pointer, respectively</dd> <dt><code>StringType</code></dt> <dd>the string type derived from the <code>json_pointer</code> operand (<a href=../string_t/ ><code>json_pointer::string_t</code></a>)</dd> </dl> <h2 id=parameters>Parameters<a class=headerlink href=#parameters title="Permanent link">&para;</a></h2> <dl> <dt><code>lhs</code> (in)</dt> <dd>first value to consider</dd> <dt><code>rhs</code> (in)</dt> <dd>second value to consider</dd> </dl> <h2 id=return-value>Return value<a class=headerlink href=#return-value title="Permanent link">&para;</a></h2> <p>whether the values <code>lhs</code>/<code>*this</code> and <code>rhs</code> are equal</p> <h2 id=exception-safety>Exception safety<a class=headerlink href=#exception-safety title="Permanent link">&para;</a></h2> <ol> <li>No-throw guarantee: this function never throws exceptions.</li> <li>Strong exception safety: if an exception occurs, the original value stays intact.</li> </ol> <h2 id=exceptions>Exceptions<a class=headerlink href=#exceptions title="Permanent link">&para;</a></h2> <ol> <li>(none)</li> <li>The function can throw the following exceptions:</li> <li>Throws <a href=../../../home/exceptions/#jsonexceptionparse_error107>parse_error.107</a> if the given <abbr title="JavaScript Object Notation">JSON</abbr> pointer <code>s</code> is nonempty and does not begin with a slash (<code>/</code>); see example below.</li> <li>Throws <a href=../../../home/exceptions/#jsonexceptionparse_error108>parse_error.108</a> if a tilde (<code>~</code>) in the given <abbr title="JavaScript Object Notation">JSON</abbr> pointer <code>s</code> is not followed by <code>0</code> (representing <code>~</code>) or <code>1</code> (representing <code>/</code>); see example below.</li> </ol> <h2 id=complexity>Complexity<a class=headerlink href=#complexity title="Permanent link">&para;</a></h2> <p>Constant if <code>lhs</code> and <code>rhs</code> differ in the number of reference tokens, otherwise linear in the number of reference tokens.</p> <h2 id=notes>Notes<a class=headerlink href=#notes title="Permanent link">&para;</a></h2> <div class="admonition warning"> <p class=admonition-title>Deprecation</p> <p>Overload 2 is deprecated and will be removed in a future major version release.</p> <p>See the <a href=../../../integration/migration_guide/#json-pointers>migration guide</a> for how to update existing code.</p> </div> <h2 id=examples>Examples<a class=headerlink href=#examples title="Permanent link">&para;</a></h2> <details class=example> <summary>Example: (1) Comparing <abbr title="JavaScript Object Notation">JSON</abbr> pointers</summary> <p>The example demonstrates comparing <abbr title="JavaScript Object Notation">JSON</abbr> pointers.</p> <div class=highlight><pre><span></span><code><span class=cp>#include</span><span class=w> </span><span class=cpf>&lt;iostream&gt;</span>
<span class=cp>#include</span><span class=w> </span><span class=cpf>&lt;nlohmann/json.hpp&gt;</span>
<span class=k>using</span><span class=w> </span><span class=n>json</span><span class=w> </span><span class=o>=</span><span class=w> </span><span class=n>nlohmann</span><span class=o>::</span><span class=n>json</span><span class=p>;</span>
@@ -82,4 +82,4 @@
"" == "": true
"/foo" == "/foo": true
"bar" == "/foo": [json.exception.parse_error.107] parse error at byte 1: JSON pointer must be empty or begin with '/' - was: 'bar'
</code></pre></div> </details> <h2 id=version-history>Version history<a class=headerlink href=#version-history title="Permanent link">&para;</a></h2> <ol> <li>Added in version 2.1.0. 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</code></pre></div> </details> <h2 id=see-also>See also<a class=headerlink href=#see-also title="Permanent link">&para;</a></h2> <ul> <li><a href=../operator_ne/ >operator!=</a> compare for inequality</li> <li><a href=../operator_spaceship/ >operator&lt;=&gt;</a> comparison: 3-way (C++20)</li> </ul> <h2 id=version-history>Version history<a class=headerlink href=#version-history title="Permanent link">&para;</a></h2> <ol> <li>Added in version 2.1.0. Added C++20 member functions in version 3.11.2.</li> <li>Added for backward compatibility and deprecated in version 3.11.2.</li> </ol> <!-- https://squidfunk.github.io/mkdocs-material/reference/tooltips/#adding-a-glossary --> <aside class=md-source-file> <span class=md-source-file__fact> <span class=md-icon title="Last update"> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M21 13.1c-.1 0-.3.1-.4.2l-1 1 2.1 2.1 1-1c.2-.2.2-.6 0-.8l-1.3-1.3c-.1-.1-.2-.2-.4-.2m-1.9 1.8-6.1 6V23h2.1l6.1-6.1zM12.5 7v5.2l4 2.4-1 1L11 13V7zM11 21.9c-5.1-.5-9-4.8-9-9.9C2 6.5 6.5 2 12 2c5.3 0 9.6 4.1 10 9.3-.3-.1-.6-.2-1-.2s-.7.1-1 .2C19.6 7.2 16.2 4 12 4c-4.4 0-8 3.6-8 8 0 4.1 3.1 7.5 7.1 7.9l-.1.2z"/></svg> </span> <span class="git-revision-date-localized-plugin git-revision-date-localized-plugin-date" title="October 2, 2026 09:32:15 UTC">October 2, 2026</span> </span> </aside> </article> </div> <script>var tabs=__md_get("__tabs");if(Array.isArray(tabs))e:for(var set of document.querySelectorAll(".tabbed-set")){var labels=set.querySelector(".tabbed-labels");for(var tab of tabs)for(var label of labels.getElementsByTagName("label"))if(label.innerText.trim()===tab){var input=document.getElementById(label.htmlFor);input.checked=!0;continue e}}</script> <script>var target=document.getElementById(location.hash.slice(1));target&&target.name&&(target.checked=target.name.startsWith("__tabbed_"))</script> </div> <button type=button class="md-top md-icon" data-md-component=top hidden> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M13 20h-2V8l-5.5 5.5-1.42-1.42L12 4.16l7.92 7.92-1.42 1.42L13 8z"/></svg> Back to top </button> </main> <footer class=md-footer> <div class="md-footer-meta md-typeset"> <div class="md-footer-meta__inner md-grid"> <div class=md-copyright> <div class=md-copyright__highlight> Copyright &copy; 2013-2026 Niels Lohmann </div> </div> <div class=md-social> <a href="https://github.com/nlohmann" target="_blank" rel="noopener" title="github.com" class="md-social__link"> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 512 512"><!-- Font Awesome Free 7.1.0 by @fontawesome - https://fontawesome.com License - https://fontawesome.com/license/free (Icons: CC BY 4.0, Fonts: SIL OFL 1.1, Code: MIT License) Copyright 2025 Fonticons, Inc.--><path d="M173.9 397.4c0 2-2.3 3.6-5.2 3.6-3.3.3-5.6-1.3-5.6-3.6 0-2 2.3-3.6 5.2-3.6 3-.3 5.6 1.3 5.6 3.6m-31.1-4.5c-.7 2 1.3 4.3 4.3 4.9 2.6 1 5.6 0 6.2-2s-1.3-4.3-4.3-5.2c-2.6-.7-5.5.3-6.2 2.3m44.2-1.7c-2.9.7-4.9 2.6-4.6 4.9.3 2 2.9 3.3 5.9 2.6 2.9-.7 4.9-2.6 4.6-4.6-.3-1.9-3-3.2-5.9-2.9M252.8 8C114.1 8 8 113.3 8 252c0 110.9 69.8 205.8 169.5 239.2 12.8 2.3 17.3-5.6 17.3-12.1 0-6.2-.3-40.4-.3-61.4 0 0-70 15-84.7-29.8 0 0-11.4-29.1-27.8-36.6 0 0-22.9-15.7 1.6-15.4 0 0 24.9 2 38.6 25.8 21.9 38.6 58.6 27.5 72.9 20.9 2.3-16 8.8-27.1 16-33.7-55.9-6.2-112.3-14.3-112.3-110.5 0-27.5 7.6-41.3 23.6-58.9-2.6-6.5-11.1-33.3 2.6-67.9 20.9-6.5 69 27 69 27 20-5.6 41.5-8.5 62.8-8.5s42.8 2.9 62.8 8.5c0 0 48.1-33.6 69-27 13.7 34.7 5.2 61.4 2.6 67.9 16 17.7 25.8 31.5 25.8 58.9 0 96.5-58.9 104.2-114.8 110.5 9.2 7.9 17 22.9 17 46.4 0 33.7-.3 75.4-.3 83.6 0 6.5 4.6 14.4 17.3 12.1C436.2 457.8 504 362.9 504 252 504 113.3 391.5 8 252.8 8M105.2 352.9c-1.3 1-1 3.3.7 5.2 1.6 1.6 3.9 2.3 5.2 1 1.3-1 1-3.3-.7-5.2-1.6-1.6-3.9-2.3-5.2-1m-10.8-8.1c-.7 1.3.3 2.9 2.3 3.9 1.6 1 3.6.7 4.3-.7.7-1.3-.3-2.9-2.3-3.9-2-.6-3.6-.3-4.3.7m32.4 35.6c-1.6 1.3-1 4.3 1.3 6.2 2.3 2.3 5.2 2.6 6.5 1 1.3-1.3.7-4.3-1.3-6.2-2.2-2.3-5.2-2.6-6.5-1m-11.4-14.7c-1.6 1-1.6 3.6 0 5.9s4.3 3.3 5.6 2.3c1.6-1.3 1.6-3.9 0-6.2-1.4-2.3-4-3.3-5.6-2"/></svg> </a> <a href="https://www.linkedin.com/in/nielslohmann/" target="_blank" rel="noopener" title="www.linkedin.com" class="md-social__link"> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 448 512"><!-- Font Awesome Free 7.1.0 by @fontawesome - https://fontawesome.com License - https://fontawesome.com/license/free (Icons: CC BY 4.0, Fonts: SIL OFL 1.1, Code: MIT License) Copyright 2025 Fonticons, Inc.--><path d="M416 32H31.9C14.3 32 0 46.5 0 64.3v383.4C0 465.5 14.3 480 31.9 480H416c17.6 0 32-14.5 32-32.3V64.3c0-17.8-14.4-32.3-32-32.3M135.4 416H69V202.2h66.5V416zM102.2 96a38.5 38.5 0 1 1 0 77 38.5 38.5 0 1 1 0-77m282.1 320h-66.4V312c0-24.8-.5-56.7-34.5-56.7-34.6 0-39.9 27-39.9 54.9V416h-66.4V202.2h63.7v29.2h.9c8.9-16.8 30.6-34.5 62.9-34.5 67.2 0 79.7 44.3 79.7 101.9z"/></svg> </a> <a href="https://www.xing.com/profile/Niels_Lohmann" target="_blank" rel="noopener" title="www.xing.com" class="md-social__link"> <svg xmlns=http://wwwLine truncated
+7
View File
@@ -68,6 +68,8 @@ Deprecation
Overload 2 is deprecated and will be removed in a future major version release.
See the [migration guide](https://json.nlohmann.me/integration/migration_guide/#json-pointers) for how to update existing code.
## Examples
Example: (1) Comparing JSON pointers
@@ -154,6 +156,11 @@ Output:
"bar" == "/foo": [json.exception.parse_error.107] parse error at byte 1: JSON pointer must be empty or begin with '/' - was: 'bar'
```
## See also
- [operator!=](https://json.nlohmann.me/api/json_pointer/operator_ne/index.md) compare for inequality
- [operator\<=>](https://json.nlohmann.me/api/json_pointer/operator_spaceship/index.md) comparison: 3-way (C++20)
## Version history
1. Added in version 2.1.0. Added C++20 member functions in version 3.11.2.
+7
View File
@@ -73,6 +73,8 @@ tokens.
Overload 2 is deprecated and will be removed in a future major version release.
See the [migration guide](../../integration/migration_guide.md#json-pointers) for how to update existing code.
## Examples
??? example "Example: (1) Comparing JSON pointers"
@@ -103,6 +105,11 @@ tokens.
--8<-- "examples/json_pointer__operator__notequal_stringtype.output"
```
## See also
- [operator==](operator_eq.md) compare for equality
- [operator<=>](operator_spaceship.md) comparison: 3-way (C++20)
## Version history
1. Added in version 2.1.0.
+3 -3
View File
@@ -1,4 +1,4 @@
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1.5-5-5v-.79l-.27-.27A6.52 6.52 0 0 1 9.5 16 6.5 6.5 0 0 1 3 9.5 6.5 6.5 0 0 1 9.5 3m0 2C7 5 5 7 5 9.5S7 14 9.5 14 14 12 1Line truncated
<span class=k>template</span><span class=o>&lt;</span><span class=k>typename</span><span class=w> </span><span class=nc>RefStringTypeLhs</span><span class=p>,</span><span class=w> </span><span class=k>typename</span><span class=w> </span><span class=nc>RefStringTypeRhs</span><span class=o>&gt;</span>
<span class=kt>bool</span><span class=w> </span><span class=k>operator</span><span class=o>!=</span><span class=p>(</span>
<span class=w> </span><span class=k>const</span><span class=w> </span><span class=n>json_pointer</span><span class=o>&lt;</span><span class=n>RefStringTypeLhs</span><span class=o>&gt;&amp;</span><span class=w> </span><span class=n>lhs</span><span class=p>,</span>
@@ -13,7 +13,7 @@
<span class=kt>bool</span><span class=w> </span><span class=k>operator</span><span class=o>!=</span><span class=p>(</span>
<span class=w> </span><span class=k>const</span><span class=w> </span><span class=n>StringType</span><span class=o>&amp;</span><span class=w> </span><span class=n>lhs</span><span class=p>,</span>
<span class=w> </span><span class=k>const</span><span class=w> </span><span class=n>json_pointer</span><span class=o>&lt;</span><span class=n>RefStringTypeRhs</span><span class=o>&gt;&amp;</span><span class=w> </span><span class=n>rhs</span><span class=p>);</span><span class=w> </span><span class=c1>// (2)</span>
</code></pre></div> <ol> <li> <p>Compares two <abbr title="JavaScript Object Notation">JSON</abbr> pointers for inequality by comparing their reference tokens.</p> </li> <li> <p>Compares a <abbr title="JavaScript Object Notation">JSON</abbr> pointer and a string or a string and a <abbr title="JavaScript Object Notation">JSON</abbr> pointer for inequality by converting the string to a <abbr title="JavaScript Object Notation">JSON</abbr> pointer and comparing the <abbr title="JavaScript Object Notation">JSON</abbr> pointers according to 1.</p> </li> </ol> <h2 id=template-parameters>Template parameters<a class=headerlink href=#template-parameters title="Permanent link">&para;</a></h2> <dl> <dt><code>RefStringTypeLhs</code>, <code>RefStringTypeRhs</code></dt> <dd>the string type of the left-hand side or right-hand side <abbr title="JavaScript Object Notation">JSON</abbr> pointer, respectively</dd> <dt><code>StringType</code></dt> <dd>the string type derived from the <code>json_pointer</code> operand (<a href=../string_t/ ><code>json_pointer::string_t</code></a>)</dd> </dl> <h2 id=parameters>Parameters<a class=headerlink href=#parameters title="Permanent link">&para;</a></h2> <dl> <dt><code>lhs</code> (in)</dt> <dd>first value to consider</dd> <dt><code>rhs</code> (in)</dt> <dd>second value to consider</dd> </dl> <h2 id=return-value>Return value<a class=headerlink href=#return-value title="Permanent link">&para;</a></h2> <p>whether the values <code>lhs</code>/<code>*this</code> and <code>rhs</code> are not equal</p> <h2 id=exception-safety>Exception safety<a class=headerlink href=#exception-safety title="Permanent link">&para;</a></h2> <ol> <li>No-throw guarantee: this function never throws exceptions.</li> <li>Strong exception safety: if an exception occurs, the original value stays intact.</li> </ol> <h2 id=exceptions>Exceptions<a class=headerlink href=#exceptions title="Permanent link">&para;</a></h2> <ol> <li>(none)</li> <li>The function can throw the following exceptions:</li> <li>Throws <a href=../../../home/exceptions/#jsonexceptionparse_error107>parse_error.107</a> if the given <abbr title="JavaScript Object Notation">JSON</abbr> pointer <code>s</code> is nonempty and does not begin with a slash (<code>/</code>); see example below.</li> <li>Throws <a href=../../../home/exceptions/#jsonexceptionparse_error108>parse_error.108</a> if a tilde (<code>~</code>) in the given <abbr title="JavaScript Object Notation">JSON</abbr> pointer <code>s</code> is not followed by <code>0</code> (representing <code>~</code>) or <code>1</code> (representing <code>/</code>); see example below.</li> </ol> <h2 id=complexity>Complexity<a class=headerlink href=#complexity title="Permanent link">&para;</a></h2> <p>Constant if <code>lhs</code> and <code>rhs</code> differ in the number of reference tokens, otherwise linear in the number of reference tokens.</p> <h2 id=notes>Notes<a class=headerlink href=#notes title="Permanent link">&para;</a></h2> <div class="admonition note"> <p class=admonition-title>Operator overload resolution</p> <p>Since C++20 overload resolution will consider the <em>rewritten candidate</em> generated from <a href=../operator_eq/ ><code>operator==</code></a>.</p> </div> <div class="admonition warning"> <p class=admonition-title>Deprecation</p> <p>Overload 2 is deprecated and will be removed in a future major version release.</p> </div> <h2 id=examples>Examples<a class=headerlink href=#examples title="Permanent link">&para;</a></h2> <details class=example> <summary>Example: (1) Comparing <abbr title="JavaScript Object Notation">JSON</abbr> pointers</summary> <p>The example demonstrates comparing <abbr title="JavaScript Object Notation">JSON</abbr> pointers.</p> <div class=highlight><pre><span></span><code><span class=cp>#include</span><span class=w> </span><span class=cpf>&lt;iostream&gt;</span>
</code></pre></div> <ol> <li> <p>Compares two <abbr title="JavaScript Object Notation">JSON</abbr> pointers for inequality by comparing their reference tokens.</p> </li> <li> <p>Compares a <abbr title="JavaScript Object Notation">JSON</abbr> pointer and a string or a string and a <abbr title="JavaScript Object Notation">JSON</abbr> pointer for inequality by converting the string to a <abbr title="JavaScript Object Notation">JSON</abbr> pointer and comparing the <abbr title="JavaScript Object Notation">JSON</abbr> pointers according to 1.</p> </li> </ol> <h2 id=template-parameters>Template parameters<a class=headerlink href=#template-parameters title="Permanent link">&para;</a></h2> <dl> <dt><code>RefStringTypeLhs</code>, <code>RefStringTypeRhs</code></dt> <dd>the string type of the left-hand side or right-hand side <abbr title="JavaScript Object Notation">JSON</abbr> pointer, respectively</dd> <dt><code>StringType</code></dt> <dd>the string type derived from the <code>json_pointer</code> operand (<a href=../string_t/ ><code>json_pointer::string_t</code></a>)</dd> </dl> <h2 id=parameters>Parameters<a class=headerlink href=#parameters title="Permanent link">&para;</a></h2> <dl> <dt><code>lhs</code> (in)</dt> <dd>first value to consider</dd> <dt><code>rhs</code> (in)</dt> <dd>second value to consider</dd> </dl> <h2 id=return-value>Return value<a class=headerlink href=#return-value title="Permanent link">&para;</a></h2> <p>whether the values <code>lhs</code>/<code>*this</code> and <code>rhs</code> are not equal</p> <h2 id=exception-safety>Exception safety<a class=headerlink href=#exception-safety title="Permanent link">&para;</a></h2> <ol> <li>No-throw guarantee: this function never throws exceptions.</li> <li>Strong exception safety: if an exception occurs, the original value stays intact.</li> </ol> <h2 id=exceptions>Exceptions<a class=headerlink href=#exceptions title="Permanent link">&para;</a></h2> <ol> <li>(none)</li> <li>The function can throw the following exceptions:</li> <li>Throws <a href=../../../home/exceptions/#jsonexceptionparse_error107>parse_error.107</a> if the given <abbr title="JavaScript Object Notation">JSON</abbr> pointer <code>s</code> is nonempty and does not begin with a slash (<code>/</code>); see example below.</li> <li>Throws <a href=../../../home/exceptions/#jsonexceptionparse_error108>parse_error.108</a> if a tilde (<code>~</code>) in the given <abbr title="JavaScript Object Notation">JSON</abbr> pointer <code>s</code> is not followed by <code>0</code> (representing <code>~</code>) or <code>1</code> (representing <code>/</code>); see example below.</li> </ol> <h2 id=complexity>Complexity<a class=headerlink href=#complexity title="Permanent link">&para;</a></h2> <p>Constant if <code>lhs</code> and <code>rhs</code> differ in the number of reference tokens, otherwise linear in the number of reference tokens.</p> <h2 id=notes>Notes<a class=headerlink href=#notes title="Permanent link">&para;</a></h2> <div class="admonition note"> <p class=admonition-title>Operator overload resolution</p> <p>Since C++20 overload resolution will consider the <em>rewritten candidate</em> generated from <a href=../operator_eq/ ><code>operator==</code></a>.</p> </div> <div class="admonition warning"> <p class=admonition-title>Deprecation</p> <p>Overload 2 is deprecated and will be removed in a future major version release.</p> <p>See the <a href=../../../integration/migration_guide/#json-pointers>migration guide</a> for how to update existing code.</p> </div> <h2 id=examples>Examples<a class=headerlink href=#examples title="Permanent link">&para;</a></h2> <details class=example> <summary>Example: (1) Comparing <abbr title="JavaScript Object Notation">JSON</abbr> pointers</summary> <p>The example demonstrates comparing <abbr title="JavaScript Object Notation">JSON</abbr> pointers.</p> <div class=highlight><pre><span></span><code><span class=cp>#include</span><span class=w> </span><span class=cpf>&lt;iostream&gt;</span>
<span class=cp>#include</span><span class=w> </span><span class=cpf>&lt;nlohmann/json.hpp&gt;</span>
<span class=k>using</span><span class=w> </span><span class=n>json</span><span class=w> </span><span class=o>=</span><span class=w> </span><span class=n>nlohmann</span><span class=o>::</span><span class=n>json</span><span class=p>;</span>
@@ -72,4 +72,4 @@
"" != "": false
"/foo" != "/foo": false
"bar" != "/foo": [json.exception.parse_error.107] parse error at byte 1: JSON pointer must be empty or begin with '/' - was: 'bar'
</code></pre></div> </details> <h2 id=version-history>Version history<a class=headerlink href=#version-history title="Permanent link">&para;</a></h2> <ol> <li>Added in version 2.1.0.</li> <li>Added for backward compatibility and deprecated in version 3.11.2.</li> </ol> <!-- https://squidfunk.github.io/mkdocs-material/reference/tooltips/#adding-a-glossary --> <aside class=md-source-file> <span class=md-source-file__fact> <span class=md-icon title="Last update"> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M21 13.1c-.1 0-.3.1-.4.2l-1 1 2.1 2.1 1-1c.2-.2.2-.6 0-.8l-1.3-1.3c-.1-.1-.2-.2-.4-.2m-1.9 1.8-6.1 6V23h2.1l6.1-6.1zM12.5 7v5.2l4 2.4-1 1L11 13V7zM11 21.9c-5.1-.5-9-4.8-9-9.9C2 6.5 6.5 2 12 2c5.3 0 9.6 4.1 10 9.3-.3-.1-.6-.2-1-.2s-.7.1-1 .2C19.6 7.2 16.2 4 12 4c-4.4 0-8 3.6-8 8 0 4.1 3.1 7.5 7.1 7.9l-.1.2z"/></svg> </span> <span class="git-revision-date-localized-plugin git-revision-date-localized-plugin-date" title="October 2, 2026 09:23:55 UTC">October 2, 2026</span> </span> </aside> </article> </div> <script>var tabs=__md_get("__tabs");if(Array.isArray(tabs))e:for(var set of document.querySelectorAll(".tabbed-set")){var labels=set.querySelector(".tabbed-labels");for(var tab of tabs)for(var label of labels.getElementsByTagName("label"))if(label.innerText.trim()===tab){var input=document.getElementById(label.htmlFor);input.checked=!0;continue e}}</script> <script>var target=document.getElementById(location.hash.slice(1));target&&target.name&&(target.checked=target.name.startsWith("__tabbed_"))</script> </div> <button type=button class="md-top md-icon" data-md-component=top hidden> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M13 20h-2V8l-5.5 5.5-1.42-1.42L12 4.16l7.92 7.92-1.42 1.42L13 8z"/></svg> Back to top </button> </main> <footer class=md-footer> <div class="md-footer-meta md-typeset"> <div class="md-footer-meta__inner md-grid"> <div class=md-copyright> <div class=md-copyright__highlight> Copyright &copy; 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</code></pre></div> </details> <h2 id=see-also>See also<a class=headerlink href=#see-also title="Permanent link">&para;</a></h2> <ul> <li><a href=../operator_eq/ >operator==</a> compare for equality</li> <li><a href=../operator_spaceship/ >operator&lt;=&gt;</a> comparison: 3-way (C++20)</li> </ul> <h2 id=version-history>Version history<a class=headerlink href=#version-history title="Permanent link">&para;</a></h2> <ol> <li>Added in version 2.1.0.</li> <li>Added for backward compatibility and deprecated in version 3.11.2.</li> </ol> <!-- https://squidfunk.github.io/mkdocs-material/reference/tooltips/#adding-a-glossary --> <aside class=md-source-file> <span class=md-source-file__fact> <span class=md-icon title="Last update"> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M21 13.1c-.1 0-.3.1-.4.2l-1 1 2.1 2.1 1-1c.2-.2.2-.6 0-.8l-1.3-1.3c-.1-.1-.2-.2-.4-.2m-1.9 1.8-6.1 6V23h2.1l6.1-6.1zM12.5 7v5.2l4 2.4-1 1L11 13V7zM11 21.9c-5.1-.5-9-4.8-9-9.9C2 6.5 6.5 2 12 2c5.3 0 9.6 4.1 10 9.3-.3-.1-.6-.2-1-.2s-.7.1-1 .2C19.6 7.2 16.2 4 12 4c-4.4 0-8 3.6-8 8 0 4.1 3.1 7.5 7.1 7.9l-.1.2z"/></svg> </span> <span class="git-revision-date-localized-plugin git-revision-date-localized-plugin-date" title="October 2, 2026 09:32:15 UTC">October 2, 2026</span> </span> </aside> </article> </div> <script>var tabs=__md_get("__tabs");if(Array.isArray(tabs))e:for(var set of document.querySelectorAll(".tabbed-set")){var labels=set.querySelector(".tabbed-labels");for(var tab of tabs)for(var label of labels.getElementsByTagName("label"))if(label.innerText.trim()===tab){var input=document.getElementById(label.htmlFor);input.checked=!0;continue e}}</script> <script>var target=document.getElementById(location.hash.slice(1));target&&target.name&&(target.checked=target.name.startsWith("__tabbed_"))</script> </div> <button type=button class="md-top md-icon" data-md-component=top hidden> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M13 20h-2V8l-5.5 5.5-1.42-1.42L12 4.16l7.92 7.92-1.42 1.42L13 8z"/></svg> Back to top </button> </main> <footer class=md-footer> <div class="md-footer-meta md-typeset"> <div class="md-footer-meta__inner md-grid"> <div class=md-copyright> <div class=md-copyright__highlight> Copyright &copy; 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+7
View File
@@ -63,6 +63,8 @@ Deprecation
Overload 2 is deprecated and will be removed in a future major version release.
See the [migration guide](https://json.nlohmann.me/integration/migration_guide/#json-pointers) for how to update existing code.
## Examples
Example: (1) Comparing JSON pointers
@@ -148,6 +150,11 @@ Output:
"bar" != "/foo": [json.exception.parse_error.107] parse error at byte 1: JSON pointer must be empty or begin with '/' - was: 'bar'
```
## See also
- [operator==](https://json.nlohmann.me/api/json_pointer/operator_eq/index.md) compare for equality
- [operator\<=>](https://json.nlohmann.me/api/json_pointer/operator_spaceship/index.md) comparison: 3-way (C++20)
## Version history
1. Added in version 2.1.0.
+10
View File
@@ -35,6 +35,11 @@ json_pointer operator/(const json_pointer& lhs, std::size_t array_idx);
2. a new JSON pointer with unescaped `token` appended to `lhs`
3. a new JSON pointer with `array_idx` appended to `lhs`
## Exception safety
Strong guarantee: if an exception is thrown, there are no changes to any JSON pointer. The operands are not modified;
a new JSON pointer is built from a copy of `lhs`.
## Complexity
1. Linear in the length of `lhs` and `rhs`.
@@ -57,6 +62,11 @@ json_pointer operator/(const json_pointer& lhs, std::size_t array_idx);
--8<-- "examples/json_pointer__operator_add_binary.output"
```
## See also
- [operator/=](operator_slasheq.md) append to the end of the JSON pointer
- [push_back](push_back.md) append an unescaped token at the end of the pointer
## Version history
1. Added in version 3.6.0.
+3 -3
View File
@@ -1,4 +1,4 @@
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1.5-5-5v-.79l-.27-.27A6.52 6.52 0 0 1 9.5 16 6.5 6.5 0 0 1 3 9.5 6.5 6.5 0 0 1 9.5 3m0 2C7 5 5 7 5 9.5S7 14 9.5 14 1Line truncated
<span class=n>json_pointer</span><span class=w> </span><span class=k>operator</span><span class=o>/</span><span class=p>(</span><span class=k>const</span><span class=w> </span><span class=n>json_pointer</span><span class=o>&amp;</span><span class=w> </span><span class=n>lhs</span><span class=p>,</span><span class=w> </span><span class=k>const</span><span class=w> </span><span class=n>json_pointer</span><span class=o>&amp;</span><span class=w> </span><span class=n>rhs</span><span class=p>);</span>
<span class=c1>// (2)</span>
@@ -6,7 +6,7 @@
<span class=c1>// (3)</span>
<span class=n>json_pointer</span><span class=w> </span><span class=k>operator</span><span class=o>/</span><span class=p>(</span><span class=k>const</span><span class=w> </span><span class=n>json_pointer</span><span class=o>&amp;</span><span class=w> </span><span class=n>lhs</span><span class=p>,</span><span class=w> </span><span class=n>std</span><span class=o>::</span><span class=kt>size_t</span><span class=w> </span><span class=n>array_idx</span><span class=p>);</span>
</code></pre></div> <ol> <li>create a new <abbr title="JavaScript Object Notation">JSON</abbr> pointer by appending the right <abbr title="JavaScript Object Notation">JSON</abbr> pointer at the end of the left <abbr title="JavaScript Object Notation">JSON</abbr> pointer</li> <li>create a new <abbr title="JavaScript Object Notation">JSON</abbr> pointer by appending the unescaped token at the end of the <abbr title="JavaScript Object Notation">JSON</abbr> pointer</li> <li>create a new <abbr title="JavaScript Object Notation">JSON</abbr> pointer by appending the array-index-token at the end of the <abbr title="JavaScript Object Notation">JSON</abbr> pointer</li> </ol> <h2 id=parameters>Parameters<a class=headerlink href=#parameters title="Permanent link">&para;</a></h2> <dl> <dt><code>lhs</code> (in)</dt> <dd><abbr title="JavaScript Object Notation">JSON</abbr> pointer</dd> <dt><code>rhs</code> (in)</dt> <dd><abbr title="JavaScript Object Notation">JSON</abbr> pointer to append</dd> <dt><code>token</code> (in)</dt> <dd>reference token to append</dd> <dt><code>array_idx</code> (in)</dt> <dd>array index to append</dd> </dl> <h2 id=return-value>Return value<a class=headerlink href=#return-value title="Permanent link">&para;</a></h2> <ol> <li>a new <abbr title="JavaScript Object Notation">JSON</abbr> pointer with <code>rhs</code> appended to <code>lhs</code></li> <li>a new <abbr title="JavaScript Object Notation">JSON</abbr> pointer with unescaped <code>token</code> appended to <code>lhs</code></li> <li>a new <abbr title="JavaScript Object Notation">JSON</abbr> pointer with <code>array_idx</code> appended to <code>lhs</code></li> </ol> <h2 id=complexity>Complexity<a class=headerlink href=#complexity title="Permanent link">&para;</a></h2> <ol> <li>Linear in the length of <code>lhs</code> and <code>rhs</code>.</li> <li>Linear in the length of <code>lhs</code>.</li> <li>Linear in the length of <code>lhs</code>.</li> </ol> <h2 id=examples>Examples<a class=headerlink href=#examples title="Permanent link">&para;</a></h2> <details class=example> <summary>Example</summary> <p>The example shows the usage of <code>operator/</code>.</p> <div class=highlight><pre><span></span><code><span class=cp>#include</span><span class=w> </span><span class=cpf>&lt;iostream&gt;</span>
</code></pre></div> <ol> <li>create a new <abbr title="JavaScript Object Notation">JSON</abbr> pointer by appending the right <abbr title="JavaScript Object Notation">JSON</abbr> pointer at the end of the left <abbr title="JavaScript Object Notation">JSON</abbr> pointer</li> <li>create a new <abbr title="JavaScript Object Notation">JSON</abbr> pointer by appending the unescaped token at the end of the <abbr title="JavaScript Object Notation">JSON</abbr> pointer</li> <li>create a new <abbr title="JavaScript Object Notation">JSON</abbr> pointer by appending the array-index-token at the end of the <abbr title="JavaScript Object Notation">JSON</abbr> pointer</li> </ol> <h2 id=parameters>Parameters<a class=headerlink href=#parameters title="Permanent link">&para;</a></h2> <dl> <dt><code>lhs</code> (in)</dt> <dd><abbr title="JavaScript Object Notation">JSON</abbr> pointer</dd> <dt><code>rhs</code> (in)</dt> <dd><abbr title="JavaScript Object Notation">JSON</abbr> pointer to append</dd> <dt><code>token</code> (in)</dt> <dd>reference token to append</dd> <dt><code>array_idx</code> (in)</dt> <dd>array index to append</dd> </dl> <h2 id=return-value>Return value<a class=headerlink href=#return-value title="Permanent link">&para;</a></h2> <ol> <li>a new <abbr title="JavaScript Object Notation">JSON</abbr> pointer with <code>rhs</code> appended to <code>lhs</code></li> <li>a new <abbr title="JavaScript Object Notation">JSON</abbr> pointer with unescaped <code>token</code> appended to <code>lhs</code></li> <li>a new <abbr title="JavaScript Object Notation">JSON</abbr> pointer with <code>array_idx</code> appended to <code>lhs</code></li> </ol> <h2 id=exception-safety>Exception safety<a class=headerlink href=#exception-safety title="Permanent link">&para;</a></h2> <p>Strong guarantee: if an exception is thrown, there are no changes to any <abbr title="JavaScript Object Notation">JSON</abbr> pointer. The operands are not modified; a new <abbr title="JavaScript Object Notation">JSON</abbr> pointer is built from a copy of <code>lhs</code>.</p> <h2 id=complexity>Complexity<a class=headerlink href=#complexity title="Permanent link">&para;</a></h2> <ol> <li>Linear in the length of <code>lhs</code> and <code>rhs</code>.</li> <li>Linear in the length of <code>lhs</code>.</li> <li>Linear in the length of <code>lhs</code>.</li> </ol> <h2 id=examples>Examples<a class=headerlink href=#examples title="Permanent link">&para;</a></h2> <details class=example> <summary>Example</summary> <p>The example shows the usage of <code>operator/</code>.</p> <div class=highlight><pre><span></span><code><span class=cp>#include</span><span class=w> </span><span class=cpf>&lt;iostream&gt;</span>
<span class=cp>#include</span><span class=w> </span><span class=cpf>&lt;nlohmann/json.hpp&gt;</span>
<span class=k>using</span><span class=w> </span><span class=n>json</span><span class=w> </span><span class=o>=</span><span class=w> </span><span class=n>nlohmann</span><span class=o>::</span><span class=n>json</span><span class=p>;</span>
@@ -28,4 +28,4 @@
</code></pre></div> <p>Output:</p> <div class=highlight><pre><span></span><code><span class=s2>"/foo/bar/baz"</span>
<span class=s2>"/foo/fob"</span>
<span class=s2>"/foo/42"</span>
</code></pre></div> </details> <h2 id=version-history>Version history<a class=headerlink href=#version-history title="Permanent link">&para;</a></h2> <ol> <li>Added in version 3.6.0.</li> <li>Added in version 3.6.0. 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</code></pre></div> </details> <h2 id=see-also>See also<a class=headerlink href=#see-also title="Permanent link">&para;</a></h2> <ul> <li><a href=../operator_slasheq/ >operator/=</a> append to the end of the <abbr title="JavaScript Object Notation">JSON</abbr> pointer</li> <li><a href=../push_back/ >push_back</a> append an unescaped token at the end of the pointer</li> </ul> <h2 id=version-history>Version history<a class=headerlink href=#version-history title="Permanent link">&para;</a></h2> <ol> <li>Added in version 3.6.0.</li> <li>Added in version 3.6.0. Changed type of <code>token</code> to <code>string_t</code> in version 3.11.0.</li> <li>Added in version 3.6.0.</li> </ol> <!-- https://squidfunk.github.io/mkdocs-material/reference/tooltips/#adding-a-glossary --> <aside class=md-source-file> <span class=md-source-file__fact> <span class=md-icon title="Last update"> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M21 13.1c-.1 0-.3.1-.4.2l-1 1 2.1 2.1 1-1c.2-.2.2-.6 0-.8l-1.3-1.3c-.1-.1-.2-.2-.4-.2m-1.9 1.8-6.1 6V23h2.1l6.1-6.1zM12.5 7v5.2l4 2.4-1 1L11 13V7zM11 21.9c-5.1-.5-9-4.8-9-9.9C2 6.5 6.5 2 12 2c5.3 0 9.6 4.1 10 9.3-.3-.1-.6-.2-1-.2s-.7.1-1 .2C19.6 7.2 16.2 4 12 4c-4.4 0-8 3.6-8 8 0 4.1 3.1 7.5 7.1 7.9l-.1.2z"/></svg> </span> <span class="git-revision-date-localized-plugin git-revision-date-localized-plugin-date" title="October 2, 2026 09:32:15 UTC">October 2, 2026</span> </span> </aside> </article> </div> <script>var tabs=__md_get("__tabs");if(Array.isArray(tabs))e:for(var set of document.querySelectorAll(".tabbed-set")){var labels=set.querySelector(".tabbed-labels");for(var tab of tabs)for(var label of labels.getElementsByTagName("label"))if(label.innerText.trim()===tab){var input=document.getElementById(label.htmlFor);input.checked=!0;continue e}}</script> <script>var target=document.getElementById(location.hash.slice(1));target&&target.name&&(target.checked=target.name.startsWith("__tabbed_"))</script> </div> <button type=button class="md-top md-icon" data-md-component=top hidden> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M13 20h-2V8l-5.5 5.5-1.42-1.42L12 4.16l7.92 7.92-1.42 1.42L13 8z"/></svg> Back to top </button> </main> <footer class=md-footer> <div class="md-footer-meta md-typeset"> <div class="md-footer-meta__inner md-grid"> <div class=md-copyright> <div class=md-copyright__highlight> Copyright &copy; 2013-2026 Niels Lohmann </div> </div> <div class=md-social> <a href="https://github.com/nlohmann" target="_blank" rel="noopener" title="github.com" class="md-social__link"> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 512 512"><!-- Font Awesome Free 7.1.0 by @fontawesome - https://fontawesome.com License - https://fontawesome.com/license/free (Icons: CC BY 4.0, Fonts: SIL OFL 1.1, Code: MIT License) Copyright 2025 Fonticons, Inc.--><path d="M173.9 397.4c0 2-2.3 3.6-5.2 3.6-3.3.3-5.6-1.3-5.6-3.6 0-2 2.3-3.6 5.2-3.6 3-.3 5.6 1.3 5.6 3.6m-31.1-4.5c-.7 2 1.3 4.3 4.3 4.9 2.6 1 5.6 0 6.2-2s-1.3-4.3-4.3-5.2c-2.6-.7-5.5.3-6.2 2.3m44.2-1.7c-2.9.7-4.9 2.6-4.6 4.9.3 2 2.9 3.3 5.9 2.6 2.9-.7 4.9-2.6 4.6-4.6-.3-1.9-3-3.2-5.9-2.9M252.8 8C114.1 8 8 113.3 8 252c0 110.9 69.8 205.8 169.5 239.2 12.8 2.3 17.3-5.6 17.3-12.1 0-6.2-.3-40.4-.3-61.4 0 0-70 15-84.7-29.8 0 0-11.4-29.1-27.8-36.6 0 0-22.9-15.7 1.6-15.4 0 0 24.9 2 38.6 25.8 21.9 38.6 58.6 27.5 72.9 20.9 2.3-16 8.8-27.1 16-33.7-55.9-6.2-112.3-14.3-112.3-110.5 0-27.5 7.6-41.3 23.6-58.9-2.6-6.5-11.1-33.3 2.6-67.9 20.9-6.5 69 27 69 27 20-5.6 41.5-8.5 62.8-8.5s42.8 2.9 62.8 8.5c0 0 48.1-33.6 69-27 13.7 34.7 5.2 61.4 2.6 67.9 16 17.7 25.8 31.5 25.8 58.9 0 96.5-58.9 104.2-114.8 110.5 9.2 7.9 17 22.9 17 46.4 0 33.7-.3 75.4-.3 83.6 0 6.5 4.6 14.4 17.3 12.1C436.2 457.8 504 362.9 504 252 504 113.3 391.5 8 252.8 8M105.2 352.9c-1.3 1-1 3.3.7 5.2 1.6 1.6 3.9 2.3 5.2 1 1.3-1 1-3.3-.7-5.2-1.6-1.6-3.9-2.3-5.2-1m-10.8-8.1c-.7 1.3.3 2.9 2.3 3.9 1.6 1 3.6.7 4.3-.7.7-1.3-.3-2.9-2.3-3.9-2-.6-3.6-.3-4.3.7m32.4 35.6c-1.6 1.3-1 4.3 1.3 6.2 2.3 2.3 5.2 2.6 6.5 1 1.3-1.3.7-4.3-1.3-6.2-2.2-2.3-5.2-2.6-6.5-1m-11.4-14.7c-1.6 1-1.6 3.6 0 5.9s4.3 3.3 5.6 2.3c1.6-1.3 1.6-3.9 0-6.2-1.4-2.3-4-3.3-5.6-2"/></svg> </a> <a href="https://www.linkedin.com/in/nielslohmann/" target="_blank" rel="noopener" title="www.linkedin.com" class="md-social__link"> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 448 512"><!-- Font Awesome Free 7.1.0 by @fontawesome - https://fontawesome.com License - https://fontawesome.com/license/free (Icons: CC BY 4.0, Fonts: SIL OFL 1.1, Code: MIT License) Copyright 2025 Fonticons, Inc.--><path d="M416 32H31.9C14.3 32 0 46.5 0 64.3v383.4C0 465.5 14.3 480 31.9 480H416c17.6 0 32-14.5 32-32.3V64.3c0-17.8-14.4-32.3-32-32.3M135.4 416H69V202.2h66.5V416zM102.2 96a38.5 38.5 0 1 1 0 77 38.5 38.5 0 1 1 0-77m282.1 320h-66.4V312c0-24.8-.5-56.7-34.5-56.7-34.6 0-39.9 27-39.9 54.9V416h-66.4V202.2h63.7v29.2h.9c8.9-16.8 30.6-34.5 62.9-34.5 67.2 0 79.7 44.3 79.7 101.9z"/></svg> </a> <a href="https://www.xing.com/profile/Niels_Lohmann" Line truncated
+9
View File
@@ -31,6 +31,10 @@ json_pointer operator/(const json_pointer& lhs, std::size_t array_idx);
1. a new JSON pointer with unescaped `token` appended to `lhs`
1. a new JSON pointer with `array_idx` appended to `lhs`
## Exception safety
Strong guarantee: if an exception is thrown, there are no changes to any JSON pointer. The operands are not modified; a new JSON pointer is built from a copy of `lhs`.
## Complexity
1. Linear in the length of `lhs` and `rhs`.
@@ -73,6 +77,11 @@ Output:
"/foo/42"
```
## See also
- [operator/=](https://json.nlohmann.me/api/json_pointer/operator_slasheq/index.md) append to the end of the JSON pointer
- [push_back](https://json.nlohmann.me/api/json_pointer/push_back/index.md) append an unescaped token at the end of the pointer
## Version history
1. Added in version 3.6.0.
+12
View File
@@ -32,6 +32,13 @@ json_pointer& operator/=(std::size_t array_idx)
2. JSON pointer with `token` appended without escaping `token`
3. JSON pointer with `array_idx` appended
## Exception safety
1. Basic guarantee: if an exception is thrown (for instance, if copying a reference token fails), the JSON pointer is
left in a valid state, but it may contain some of the reference tokens of `ptr`.
2. Strong guarantee: if an exception is thrown, there are no changes to the JSON pointer.
3. Strong guarantee: if an exception is thrown, there are no changes to the JSON pointer.
## Complexity
1. Linear in the length of `ptr`.
@@ -54,6 +61,11 @@ json_pointer& operator/=(std::size_t array_idx)
--8<-- "examples/json_pointer__operator_add.output"
```
## See also
- [operator/](operator_slash.md) create JSON Pointer by appending
- [push_back](push_back.md) append an unescaped token at the end of the pointer
## Version history
1. Added in version 3.6.0.
+3 -3
View File
@@ -1,4 +1,4 @@
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<span class=n>json_pointer</span><span class=o>&amp;</span><span class=w> </span><span class=k>operator</span><span class=o>/=</span><span class=p>(</span><span class=k>const</span><span class=w> </span><span class=n>json_pointer</span><span class=o>&amp;</span><span class=w> </span><span class=n>ptr</span><span class=p>);</span>
<span class=c1>// (2)</span>
@@ -6,7 +6,7 @@
<span class=c1>// (3)</span>
<span class=n>json_pointer</span><span class=o>&amp;</span><span class=w> </span><span class=k>operator</span><span class=o>/=</span><span class=p>(</span><span class=n>std</span><span class=o>::</span><span class=kt>size_t</span><span class=w> </span><span class=n>array_idx</span><span class=p>)</span>
</code></pre></div> <ol> <li>append another <abbr title="JavaScript Object Notation">JSON</abbr> pointer at the end of this <abbr title="JavaScript Object Notation">JSON</abbr> pointer</li> <li>append an unescaped reference token at the end of this <abbr title="JavaScript Object Notation">JSON</abbr> pointer</li> <li>append an array index at the end of this <abbr title="JavaScript Object Notation">JSON</abbr> pointer</li> </ol> <h2 id=parameters>Parameters<a class=headerlink href=#parameters title="Permanent link">&para;</a></h2> <dl> <dt><code>ptr</code> (in)</dt> <dd><abbr title="JavaScript Object Notation">JSON</abbr> pointer to append</dd> <dt><code>token</code> (in)</dt> <dd>reference token to append</dd> <dt><code>array_idx</code> (in)</dt> <dd>array index to append</dd> </dl> <h2 id=return-value>Return value<a class=headerlink href=#return-value title="Permanent link">&para;</a></h2> <ol> <li><abbr title="JavaScript Object Notation">JSON</abbr> pointer with <code>ptr</code> appended</li> <li><abbr title="JavaScript Object Notation">JSON</abbr> pointer with <code>token</code> appended without escaping <code>token</code></li> <li><abbr title="JavaScript Object Notation">JSON</abbr> pointer with <code>array_idx</code> appended</li> </ol> <h2 id=complexity>Complexity<a class=headerlink href=#complexity title="Permanent link">&para;</a></h2> <ol> <li>Linear in the length of <code>ptr</code>.</li> <li>Amortized constant.</li> <li>Amortized constant.</li> </ol> <h2 id=examples>Examples<a class=headerlink href=#examples title="Permanent link">&para;</a></h2> <details class=example> <summary>Example</summary> <p>The example shows the usage of <code>operator/=</code>.</p> <div class=highlight><pre><span></span><code><span class=cp>#include</span><span class=w> </span><span class=cpf>&lt;iostream&gt;</span>
</code></pre></div> <ol> <li>append another <abbr title="JavaScript Object Notation">JSON</abbr> pointer at the end of this <abbr title="JavaScript Object Notation">JSON</abbr> pointer</li> <li>append an unescaped reference token at the end of this <abbr title="JavaScript Object Notation">JSON</abbr> pointer</li> <li>append an array index at the end of this <abbr title="JavaScript Object Notation">JSON</abbr> pointer</li> </ol> <h2 id=parameters>Parameters<a class=headerlink href=#parameters title="Permanent link">&para;</a></h2> <dl> <dt><code>ptr</code> (in)</dt> <dd><abbr title="JavaScript Object Notation">JSON</abbr> pointer to append</dd> <dt><code>token</code> (in)</dt> <dd>reference token to append</dd> <dt><code>array_idx</code> (in)</dt> <dd>array index to append</dd> </dl> <h2 id=return-value>Return value<a class=headerlink href=#return-value title="Permanent link">&para;</a></h2> <ol> <li><abbr title="JavaScript Object Notation">JSON</abbr> pointer with <code>ptr</code> appended</li> <li><abbr title="JavaScript Object Notation">JSON</abbr> pointer with <code>token</code> appended without escaping <code>token</code></li> <li><abbr title="JavaScript Object Notation">JSON</abbr> pointer with <code>array_idx</code> appended</li> </ol> <h2 id=exception-safety>Exception safety<a class=headerlink href=#exception-safety title="Permanent link">&para;</a></h2> <ol> <li>Basic guarantee: if an exception is thrown (for instance, if copying a reference token fails), the <abbr title="JavaScript Object Notation">JSON</abbr> pointer is left in a valid state, but it may contain some of the reference tokens of <code>ptr</code>.</li> <li>Strong guarantee: if an exception is thrown, there are no changes to the <abbr title="JavaScript Object Notation">JSON</abbr> pointer.</li> <li>Strong guarantee: if an exception is thrown, there are no changes to the <abbr title="JavaScript Object Notation">JSON</abbr> pointer.</li> </ol> <h2 id=complexity>Complexity<a class=headerlink href=#complexity title="Permanent link">&para;</a></h2> <ol> <li>Linear in the length of <code>ptr</code>.</li> <li>Amortized constant.</li> <li>Amortized constant.</li> </ol> <h2 id=examples>Examples<a class=headerlink href=#examples title="Permanent link">&para;</a></h2> <details class=example> <summary>Example</summary> <p>The example shows the usage of <code>operator/=</code>.</p> <div class=highlight><pre><span></span><code><span class=cp>#include</span><span class=w> </span><span class=cpf>&lt;iostream&gt;</span>
<span class=cp>#include</span><span class=w> </span><span class=cpf>&lt;nlohmann/json.hpp&gt;</span>
<span class=k>using</span><span class=w> </span><span class=n>json</span><span class=w> </span><span class=o>=</span><span class=w> </span><span class=n>nlohmann</span><span class=o>::</span><span class=n>json</span><span class=p>;</span>
@@ -33,4 +33,4 @@
<span class=s2>"/foo/bar/baz"</span>
<span class=s2>"/foo/bar/baz/fob"</span>
<span class=s2>"/foo/bar/baz/fob/42"</span>
</code></pre></div> </details> <h2 id=version-history>Version history<a class=headerlink href=#version-history title="Permanent link">&para;</a></h2> <ol> <li>Added in version 3.6.0.</li> <li>Added in version 3.6.0. 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</code></pre></div> </details> <h2 id=see-also>See also<a class=headerlink href=#see-also title="Permanent link">&para;</a></h2> <ul> <li><a href=../operator_slash/ >operator/</a> create <abbr title="JavaScript Object Notation">JSON</abbr> Pointer by appending</li> <li><a href=../push_back/ >push_back</a> append an unescaped token at the end of the pointer</li> </ul> <h2 id=version-history>Version history<a class=headerlink href=#version-history title="Permanent link">&para;</a></h2> <ol> <li>Added in version 3.6.0.</li> <li>Added in version 3.6.0. Changed type of <code>token</code> to <code>string_t</code> in version 3.11.0.</li> <li>Added in version 3.6.0.</li> </ol> <!-- https://squidfunk.github.io/mkdocs-material/reference/tooltips/#adding-a-glossary --> <aside class=md-source-file> <span class=md-source-file__fact> <span class=md-icon title="Last update"> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M21 13.1c-.1 0-.3.1-.4.2l-1 1 2.1 2.1 1-1c.2-.2.2-.6 0-.8l-1.3-1.3c-.1-.1-.2-.2-.4-.2m-1.9 1.8-6.1 6V23h2.1l6.1-6.1zM12.5 7v5.2l4 2.4-1 1L11 13V7zM11 21.9c-5.1-.5-9-4.8-9-9.9C2 6.5 6.5 2 12 2c5.3 0 9.6 4.1 10 9.3-.3-.1-.6-.2-1-.2s-.7.1-1 .2C19.6 7.2 16.2 4 12 4c-4.4 0-8 3.6-8 8 0 4.1 3.1 7.5 7.1 7.9l-.1.2z"/></svg> </span> <span class="git-revision-date-localized-plugin git-revision-date-localized-plugin-date" title="October 2, 2026 09:32:15 UTC">October 2, 2026</span> </span> </aside> </article> </div> <script>var tabs=__md_get("__tabs");if(Array.isArray(tabs))e:for(var set of document.querySelectorAll(".tabbed-set")){var labels=set.querySelector(".tabbed-labels");for(var tab of tabs)for(var label of labels.getElementsByTagName("label"))if(label.innerText.trim()===tab){var input=document.getElementById(label.htmlFor);input.checked=!0;continue e}}</script> <script>var target=document.getElementById(location.hash.slice(1));target&&target.name&&(target.checked=target.name.startsWith("__tabbed_"))</script> </div> <button type=button class="md-top md-icon" data-md-component=top hidden> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M13 20h-2V8l-5.5 5.5-1.42-1.42L12 4.16l7.92 7.92-1.42 1.42L13 8z"/></svg> Back to top </button> </main> <footer class=md-footer> <div class="md-footer-meta md-typeset"> <div class="md-footer-meta__inner md-grid"> <div class=md-copyright> <div class=md-copyright__highlight> Copyright &copy; 2013-2026 Niels Lohmann </div> </div> <div class=md-social> <a href="https://github.com/nlohmann" target="_blank" rel="noopener" title="github.com" class="md-social__link"> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 512 512"><!-- Font Awesome Free 7.1.0 by @fontawesome - https://fontawesome.com License - https://fontawesome.com/license/free (Icons: CC BY 4.0, Fonts: SIL OFL 1.1, Code: MIT License) Copyright 2025 Fonticons, Inc.--><path d="M173.9 397.4c0 2-2.3 3.6-5.2 3.6-3.3.3-5.6-1.3-5.6-3.6 0-2 2.3-3.6 5.2-3.6 3-.3 5.6 1.3 5.6 3.6m-31.1-4.5c-.7 2 1.3 4.3 4.3 4.9 2.6 1 5.6 0 6.2-2s-1.3-4.3-4.3-5.2c-2.6-.7-5.5.3-6.2 2.3m44.2-1.7c-2.9.7-4.9 2.6-4.6 4.9.3 2 2.9 3.3 5.9 2.6 2.9-.7 4.9-2.6 4.6-4.6-.3-1.9-3-3.2-5.9-2.9M252.8 8C114.1 8 8 113.3 8 252c0 110.9 69.8 205.8 169.5 239.2 12.8 2.3 17.3-5.6 17.3-12.1 0-6.2-.3-40.4-.3-61.4 0 0-70 15-84.7-29.8 0 0-11.4-29.1-27.8-36.6 0 0-22.9-15.7 1.6-15.4 0 0 24.9 2 38.6 25.8 21.9 38.6 58.6 27.5 72.9 20.9 2.3-16 8.8-27.1 16-33.7-55.9-6.2-112.3-14.3-112.3-110.5 0-27.5 7.6-41.3 23.6-58.9-2.6-6.5-11.1-33.3 2.6-67.9 20.9-6.5 69 27 69 27 20-5.6 41.5-8.5 62.8-8.5s42.8 2.9 62.8 8.5c0 0 48.1-33.6 69-27 13.7 34.7 5.2 61.4 2.6 67.9 16 17.7 25.8 31.5 25.8 58.9 0 96.5-58.9 104.2-114.8 110.5 9.2 7.9 17 22.9 17 46.4 0 33.7-.3 75.4-.3 83.6 0 6.5 4.6 14.4 17.3 12.1C436.2 457.8 504 362.9 504 252 504 113.3 391.5 8 252.8 8M105.2 352.9c-1.3 1-1 3.3.7 5.2 1.6 1.6 3.9 2.3 5.2 1 1.3-1 1-3.3-.7-5.2-1.6-1.6-3.9-2.3-5.2-1m-10.8-8.1c-.7 1.3.3 2.9 2.3 3.9 1.6 1 3.6.7 4.3-.7.7-1.3-.3-2.9-2.3-3.9-2-.6-3.6-.3-4.3.7m32.4 35.6c-1.6 1.3-1 4.3 1.3 6.2 2.3 2.3 5.2 2.6 6.5 1 1.3-1.3.7-4.3-1.3-6.2-2.2-2.3-5.2-2.6-6.5-1m-11.4-14.7c-1.6 1-1.6 3.6 0 5.9s4.3 3.3 5.6 2.3c1.6-1.3 1.6-3.9 0-6.2-1.4-2.3-4-3.3-5.6-2"/></svg> </a> <a href="https://www.linkedin.com/in/nielslohmann/" target="_blank" rel="noopener" title="www.linkedin.com" class="md-social__link"> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 448 512"><!-- Font Awesome Free 7.1.0 by @fontawesome - https://fontawesome.com License - https://fontawesome.com/license/free (Icons: CC BY 4.0, Fonts: SIL OFL 1.1, Code: MIT License) Copyright 2025 Fonticons, Inc.--><path d="M416 32H31.9C14.3 32 0 46.5 0 64.3v383.4C0 465.5 14.3 480 31.9 480H416c17.6 0 32-14.5 32-32.3V64.3c0-17.8-14.4-32.3-32-32.3M135.4 416H69V202.2h66.5V416zM102.2 96a38.5 38.5 0 1 1 0 77 38.5 38.5 0 1 1 0-77m282.1 320h-66.4V312c0-24.8-.5-56.7-34.5-56.7-34.6 0-39.9 27-39.9 54.9V416h-66.4V202.2h63.7v29.2h.9c8.9-16.8 30.6-34.5 62.9-34.5 67.2 0 79.7 44.3 79.7 101.9z"/></svg> </a> <a href="https://www.xing.com/profile/Niels_Lohmann" target="Line truncated
@@ -29,6 +29,12 @@ json_pointer& operator/=(std::size_t array_idx)
1. JSON pointer with `token` appended without escaping `token`
1. JSON pointer with `array_idx` appended
## Exception safety
1. Basic guarantee: if an exception is thrown (for instance, if copying a reference token fails), the JSON pointer is left in a valid state, but it may contain some of the reference tokens of `ptr`.
1. Strong guarantee: if an exception is thrown, there are no changes to the JSON pointer.
1. Strong guarantee: if an exception is thrown, there are no changes to the JSON pointer.
## Complexity
1. Linear in the length of `ptr`.
@@ -76,6 +82,11 @@ Output:
"/foo/bar/baz/fob/42"
```
## See also
- [operator/](https://json.nlohmann.me/api/json_pointer/operator_slash/index.md) create JSON Pointer by appending
- [push_back](https://json.nlohmann.me/api/json_pointer/push_back/index.md) append an unescaped token at the end of the pointer
## Version history
1. Added in version 3.6.0.
+74
View File
@@ -0,0 +1,74 @@
# <small>nlohmann::json_pointer::</small>operator<=>
```cpp
// since C++20
class json_pointer {
template<typename RefStringTypeRhs>
std::strong_ordering operator<=>(const json_pointer<RefStringTypeRhs>& rhs) const noexcept; // *NOPAD*
};
```
3-way compares two JSON pointers by lexicographically comparing their sequences of reference tokens: corresponding
reference tokens are compared with `string_t`'s own `operator<=>`, and the first pair of tokens that differs
determines the result. If all corresponding reference tokens compare equal, the JSON pointer with fewer reference
tokens is ordered first.
## Template parameters
`RefStringTypeRhs`
: the string type of the right-hand side JSON pointer
## Parameters
`rhs` (in)
: JSON pointer to compare `*this` with
## Return value
the `std::strong_ordering` of the 3-way comparison of `*this` and `rhs`
## Exception safety
No-throw guarantee: this function never throws exceptions.
## Complexity
Linear in the number of reference tokens.
## Notes
!!! note "Ordering enables use as an associative container key"
Together with [`operator==`](operator_eq.md), `operator<=>` makes `json_pointer` a `LessThanComparable` type, so
it can be used as the key type of ordered associative containers such as `std::map` or `std::set`.
!!! note "Before C++20"
Without C++20's three-way comparison, `json_pointer` provides a non-member `operator<` instead, which orders JSON
pointers the same way. JSON pointers can therefore be used as keys of ordered associative containers with any
supported C++ standard.
## Examples
??? example
The example demonstrates 3-way comparing JSON pointers.
```cpp
--8<-- "examples/json_pointer__operator_spaceship.c++20.cpp"
```
Output:
```
--8<-- "examples/json_pointer__operator_spaceship.c++20.output"
```
## See also
- [operator==](operator_eq.md) compare: equal
- [operator!=](operator_ne.md) compare: not equal
## Version history
- Added in version 3.11.2.
@@ -0,0 +1,41 @@
<!doctype html><html lang=en class=no-js> <head><meta charset=utf-8><meta name=viewport content="width=device-width,initial-scale=1"><meta name=author content="Niels Lohmann"><link href="https://json.nlohmann.me/api/json_pointer/operator_spaceship/" rel="canonical"><link href=../operator_ne/ rel=prev><link href=../operator_slash/ rel=next><link rel=icon href=../../../assets/images/favicon.png><meta name=generator content="mkdocs-1.6.1, mkdocs-material-9.7.7"><title>operator - JSON for Modern C++</title><link rel=stylesheet href=../../../assets/stylesheets/main.ec1eaa64.min.css><link rel=stylesheet href=../../../assets/stylesheets/palette.ab4e12ef.min.css><link rel="stylesheet" href="../../../assets/external/fonts.googleapis.com/css.61a430c9.css"><style>:root{--md-text-font:"Roboto";--md-code-font:"JetBrains Mono"}</style><link rel=stylesheet href=../../../css/custom.css><script>__md_scope=new 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<span class=k>class</span><span class=w> </span><span class=nc>json_pointer</span><span class=w> </span><span class=p>{</span>
<span class=w> </span><span class=k>template</span><span class=o>&lt;</span><span class=k>typename</span><span class=w> </span><span class=nc>RefStringTypeRhs</span><span class=o>&gt;</span>
<span class=w> </span><span class=n>std</span><span class=o>::</span><span class=n>strong_ordering</span><span class=w> </span><span class=k>operator</span><span class=o>&lt;=&gt;</span><span class=p>(</span><span class=k>const</span><span class=w> </span><span class=n>json_pointer</span><span class=o>&lt;</span><span class=n>RefStringTypeRhs</span><span class=o>&gt;&amp;</span><span class=w> </span><span class=n>rhs</span><span class=p>)</span><span class=w> </span><span class=k>const</span><span class=w> </span><span class=k>noexcept</span><span class=p>;</span><span class=w> </span><span class=c1>// *NOPAD*</span>
<span class=p>};</span>
</code></pre></div> <p>3-way compares two <abbr title="JavaScript Object Notation">JSON</abbr> pointers by lexicographically comparing their sequences of reference tokens: corresponding reference tokens are compared with <code>string_t</code>'s own <code>operator&lt;=&gt;</code>, and the first pair of tokens that differs determines the result. If all corresponding reference tokens compare equal, the <abbr title="JavaScript Object Notation">JSON</abbr> pointer with fewer reference tokens is ordered first.</p> <h2 id=template-parameters>Template parameters<a class=headerlink href=#template-parameters title="Permanent link">&para;</a></h2> <dl> <dt><code>RefStringTypeRhs</code></dt> <dd>the string type of the right-hand side <abbr title="JavaScript Object Notation">JSON</abbr> pointer</dd> </dl> <h2 id=parameters>Parameters<a class=headerlink href=#parameters title="Permanent link">&para;</a></h2> <dl> <dt><code>rhs</code> (in)</dt> <dd><abbr title="JavaScript Object Notation">JSON</abbr> pointer to compare <code>*this</code> with</dd> </dl> <h2 id=return-value>Return value<a class=headerlink href=#return-value title="Permanent link">&para;</a></h2> <p>the <code>std::strong_ordering</code> of the 3-way comparison of <code>*this</code> and <code>rhs</code></p> <h2 id=exception-safety>Exception safety<a class=headerlink href=#exception-safety title="Permanent link">&para;</a></h2> <p>No-throw guarantee: this function never throws exceptions.</p> <h2 id=complexity>Complexity<a class=headerlink href=#complexity title="Permanent link">&para;</a></h2> <p>Linear in the number of reference tokens.</p> <h2 id=notes>Notes<a class=headerlink href=#notes title="Permanent link">&para;</a></h2> <div class="admonition note"> <p class=admonition-title>Ordering enables use as an associative container key</p> <p>Together with <a href=../operator_eq/ ><code>operator==</code></a>, <code>operator&lt;=&gt;</code> makes <code>json_pointer</code> a <code>LessThanComparable</code> type, so it can be used as the key type of ordered associative containers such as <code>std::map</code> or <code>std::set</code>.</p> </div> <div class="admonition note"> <p class=admonition-title>Before C++20</p> <p>Without C++20's three-way comparison, <code>json_pointer</code> provides a non-member <code>operator&lt;</code> instead, which orders <abbr title="JavaScript Object Notation">JSON</abbr> pointers the same way. <abbr title="JavaScript Object Notation">JSON</abbr> pointers can therefore be used as keys of ordered associative containers with any supported C++ standard.</p> </div> <h2 id=examples>Examples<a class=headerlink href=#examples title="Permanent link">&para;</a></h2> <details class=example> <summary>Example</summary> <p>The example demonstrates 3-way comparing <abbr title="JavaScript Object Notation">JSON</abbr> pointers.</p> <div class=highlight><pre><span></span><code><span class=cp>#include</span><span class=w> </span><span class=cpf>&lt;compare&gt;</span>
<span class=cp>#include</span><span class=w> </span><span class=cpf>&lt;iostream&gt;</span>
<span class=cp>#include</span><span class=w> </span><span class=cpf>&lt;nlohmann/json.hpp&gt;</span>
<span class=k>using</span><span class=w> </span><span class=n>json</span><span class=w> </span><span class=o>=</span><span class=w> </span><span class=n>nlohmann</span><span class=o>::</span><span class=n>json</span><span class=p>;</span>
<span class=k>const</span><span class=w> </span><span class=kt>char</span><span class=o>*</span><span class=w> </span><span class=nf>to_string</span><span class=p>(</span><span class=k>const</span><span class=w> </span><span class=n>std</span><span class=o>::</span><span class=n>strong_ordering</span><span class=o>&amp;</span><span class=w> </span><span class=n>so</span><span class=p>)</span>
<span class=p>{</span>
<span class=w> </span><span class=k>if</span><span class=w> </span><span class=p>(</span><span class=n>std</span><span class=o>::</span><span class=n>is_lt</span><span class=p>(</span><span class=n>so</span><span class=p>))</span>
<span class=w> </span><span class=p>{</span>
<span class=w> </span><span class=k>return</span><span class=w> </span><span class=s>"less"</span><span class=p>;</span>
<span class=w> </span><span class=p>}</span>
<span class=w> </span><span class=k>else</span><span class=w> </span><span class=k>if</span><span class=w> </span><span class=p>(</span><span class=n>std</span><span class=o>::</span><span class=n>is_gt</span><span class=p>(</span><span class=n>so</span><span class=p>))</span>
<span class=w> </span><span class=p>{</span>
<span class=w> </span><span class=k>return</span><span class=w> </span><span class=s>"greater"</span><span class=p>;</span>
<span class=w> </span><span class=p>}</span>
<span class=w> </span><span class=k>return</span><span class=w> </span><span class=s>"equal"</span><span class=p>;</span>
<span class=p>}</span>
<span class=kt>int</span><span class=w> </span><span class=nf>main</span><span class=p>()</span>
<span class=p>{</span>
<span class=w> </span><span class=c1>// different JSON pointers</span>
<span class=w> </span><span class=n>json</span><span class=o>::</span><span class=n>json_pointer</span><span class=w> </span><span class=n>ptr1</span><span class=p>(</span><span class=s>"/a/b"</span><span class=p>);</span>
<span class=w> </span><span class=n>json</span><span class=o>::</span><span class=n>json_pointer</span><span class=w> </span><span class=n>ptr2</span><span class=p>(</span><span class=s>"/a/c"</span><span class=p>);</span>
<span class=w> </span><span class=n>json</span><span class=o>::</span><span class=n>json_pointer</span><span class=w> </span><span class=n>ptr3</span><span class=p>(</span><span class=s>"/a/b/c"</span><span class=p>);</span>
<span class=w> </span><span class=n>json</span><span class=o>::</span><span class=n>json_pointer</span><span class=w> </span><span class=n>ptr4</span><span class=p>(</span><span class=s>"/a/b"</span><span class=p>);</span>
<span class=w> </span><span class=c1>// 3-way compare JSON pointers</span>
<span class=w> </span><span class=n>std</span><span class=o>::</span><span class=n>cout</span><span class=w> </span><span class=o>&lt;&lt;</span><span class=w> </span><span class=s>"</span><span class=se>\"</span><span class=s>"</span><span class=w> </span><span class=o>&lt;&lt;</span><span class=w> </span><span class=n>ptr1</span><span class=w> </span><span class=o>&lt;&lt;</span><span class=w> </span><span class=s>"</span><span class=se>\"</span><span class=s> &lt;=&gt; </span><span class=se>\"</span><span class=s>"</span><span class=w> </span><span class=o>&lt;&lt;</span><span class=w> </span><span class=n>ptr2</span><span class=w> </span><span class=o>&lt;&lt;</span><span class=w> </span><span class=s>"</span><span class=se>\"</span><span class=s>: "</span><span class=w> </span><span class=o>&lt;&lt;</span><span class=w> </span><span class=n>to_string</span><span class=p>(</span><span class=n>ptr1</span><span class=w> </span><span class=o>&lt;=&gt;</span><span class=w> </span><span class=n>ptr2</span><span class=p>)</span><span class=w> </span><span class=o>&lt;&lt;</span><span class=w> </span><span class=sc>'\n'</span><span class=w> </span><span class=c1>// *NOPAD*</span>
<span class=w> </span><span class=o>&lt;&lt;</span><span class=w> </span><span class=s>"</span><span class=se>\"</span><span class=s>"</span><span class=w> </span><span class=o>&lt;&lt;</span><span class=w> </span><span class=n>ptr1</span><span class=w> </span><span class=o>&lt;&lt;</span><span class=w> </span><span class=s>"</span><span class=se>\"</span><span class=s> &lt;=&gt; </span><span class=se>\"</span><span class=s>"</span><span class=w> </span><span class=o>&lt;&lt;</span><span class=w> </span><span class=n>ptr3</span><span class=w> </span><span class=o>&lt;&lt;</span><span class=w> </span><span class=s>"</span><span class=se>\"</span><span class=s>: "</span><span class=w> </span><span class=o>&lt;&lt;</span><span class=w> </span><span class=n>to_string</span><span class=p>(</span><span class=n>ptr1</span><span class=w> </span><span class=o>&lt;=&gt;</span><span class=w> </span><span class=n>ptr3</span><span class=p>)</span><span class=w> </span><span class=o>&lt;&lt;</span><span class=w> </span><span class=sc>'\n'</span><span class=w> </span><span class=c1>// *NOPAD*</span>
<span class=w> </span><span class=o>&lt;&lt;</span><span class=w> </span><span class=s>"</span><span class=se>\"</span><span class=s>"</span><span class=w> </span><span class=o>&lt;&lt;</span><span class=w> </span><span class=n>ptr1</span><span class=w> </span><span class=o>&lt;&lt;</span><span class=w> </span><span class=s>"</span><span class=se>\"</span><span class=s> &lt;=&gt; </span><span class=se>\"</span><span class=s>"</span><span class=w> </span><span class=o>&lt;&lt;</span><span class=w> </span><span class=n>ptr4</span><span class=w> </span><span class=o>&lt;&lt;</span><span class=w> </span><span class=s>"</span><span class=se>\"</span><span class=s>: "</span><span class=w> </span><span class=o>&lt;&lt;</span><span class=w> </span><span class=n>to_string</span><span class=p>(</span><span class=n>ptr1</span><span class=w> </span><span class=o>&lt;=&gt;</span><span class=w> </span><span class=n>ptr4</span><span class=p>)</span><span class=w> </span><span class=o>&lt;&lt;</span><span class=w> </span><span class=n>std</span><span class=o>::</span><span class=n>endl</span><span class=p>;</span><span class=w> </span><span class=c1>// *NOPAD*</span>
<span class=p>}</span>
</code></pre></div> <p>Output:</p> <div class=highlight><pre><span></span><code>"/a/b" &lt;=&gt; "/a/c": less
"/a/b" &lt;=&gt; "/a/b/c": less
"/a/b" &lt;=&gt; "/a/b": equal
</code></pre></div> </details> <h2 id=see-also>See also<a class=headerlink href=#see-also title="Permanent link">&para;</a></h2> <ul> <li><a href=../operator_eq/ >operator==</a> compare: equal</li> <li><a href=../operator_ne/ >operator!=</a> compare: not equal</li> </ul> <h2 id=version-history>Version history<a class=headerlink href=#version-history title="Permanent link">&para;</a></h2> <ul> <li>Added in version 3.11.2.</li> </ul> <!-- https://squidfunk.github.io/mkdocs-material/reference/tooltips/#adding-a-glossary --> <aside class=md-source-file> <span class=md-source-file__fact> <span class=md-icon title="Last update"> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M21 13.1c-.1 0-.3.1-.4.2l-1 1 2.1 2.1 1-1c.2-.2.2-.6 0-.8l-1.3-1.3c-.1-.1-.2-.2-.4-.2m-1.9 1.8-6.1 6V23h2.1l6.1-6.1zM12.5 7v5.2l4 2.4-1 1L11 13V7zM11 21.9c-5.1-.5-9-4.8-9-9.9C2 6.5 6.5 2 12 2c5.3 0 9.6 4.1 10 9.3-.3-.1-.6-.2-1-.2s-.7.1-1 .2C19.6 7.2 16.2 4 12 4c-4.4 0-8 3.6-8 8 0 4.1 3.1 7.5 7.1 7.9l-.1.2z"/></svg> </span> <span class="git-revision-date-localized-plugin git-revision-date-localized-plugin-date" title="October 2, 2026 09:32:15 UTC">October 2, 2026</span> </span> </aside> </article> </div> <script>var tabs=__md_get("__tabs");if(Array.isArray(tabs))e:for(var set of document.querySelectorAll(".tabbed-set")){var labels=set.querySelector(".tabbed-labels");for(var tab of tabs)for(var label of labels.getElementsByTagName("label"))if(label.innerText.trim()===tab){var input=document.getElementById(label.htmlFor);input.checked=!0;continue e}}</script> <script>var target=document.getElementById(location.hash.slice(1));target&&target.name&&(target.checked=target.name.startsWith("__tabbed_"))</script> </div> <button type=button class="md-top md-icon" data-md-component=top hidden> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M13 20h-2V8l-5.5 5.5-1.42-1.42L12 4.16l7.92 7.92-1.42 1.42L13 8z"/></svg> Back to top </button> </main> <footer class=md-footer> <div class="md-footer-meta md-typeset"> <div class="md-footer-meta__inner md-grid"> <div class=md-copyright> <div class=md-copyright__highlight> Copyright &copy; 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# nlohmann::json_pointer::operator\<=>
```
// since C++20
class json_pointer {
template<typename RefStringTypeRhs>
std::strong_ordering operator<=>(const json_pointer<RefStringTypeRhs>& rhs) const noexcept; // *NOPAD*
};
```
3-way compares two JSON pointers by lexicographically comparing their sequences of reference tokens: corresponding reference tokens are compared with `string_t`'s own `operator<=>`, and the first pair of tokens that differs determines the result. If all corresponding reference tokens compare equal, the JSON pointer with fewer reference tokens is ordered first.
## Template parameters
`RefStringTypeRhs` : the string type of the right-hand side JSON pointer
## Parameters
`rhs` (in) : JSON pointer to compare `*this` with
## Return value
the `std::strong_ordering` of the 3-way comparison of `*this` and `rhs`
## Exception safety
No-throw guarantee: this function never throws exceptions.
## Complexity
Linear in the number of reference tokens.
## Notes
Ordering enables use as an associative container key
Together with [`operator==`](https://json.nlohmann.me/api/json_pointer/operator_eq/index.md), `operator<=>` makes `json_pointer` a `LessThanComparable` type, so it can be used as the key type of ordered associative containers such as `std::map` or `std::set`.
Before C++20
Without C++20's three-way comparison, `json_pointer` provides a non-member `operator<` instead, which orders JSON pointers the same way. JSON pointers can therefore be used as keys of ordered associative containers with any supported C++ standard.
## Examples
Example
The example demonstrates 3-way comparing JSON pointers.
```
#include <compare>
#include <iostream>
#include <nlohmann/json.hpp>
using json = nlohmann::json;
const char* to_string(const std::strong_ordering& so)
{
if (std::is_lt(so))
{
return "less";
}
else if (std::is_gt(so))
{
return "greater";
}
return "equal";
}
int main()
{
// different JSON pointers
json::json_pointer ptr1("/a/b");
json::json_pointer ptr2("/a/c");
json::json_pointer ptr3("/a/b/c");
json::json_pointer ptr4("/a/b");
// 3-way compare JSON pointers
std::cout << "\"" << ptr1 << "\" <=> \"" << ptr2 << "\": " << to_string(ptr1 <=> ptr2) << '\n' // *NOPAD*
<< "\"" << ptr1 << "\" <=> \"" << ptr3 << "\": " << to_string(ptr1 <=> ptr3) << '\n' // *NOPAD*
<< "\"" << ptr1 << "\" <=> \"" << ptr4 << "\": " << to_string(ptr1 <=> ptr4) << std::endl; // *NOPAD*
}
```
Output:
```
"/a/b" <=> "/a/c": less
"/a/b" <=> "/a/b/c": less
"/a/b" <=> "/a/b": equal
```
## See also
- [operator==](https://json.nlohmann.me/api/json_pointer/operator_eq/index.md) compare: equal
- [operator!=](https://json.nlohmann.me/api/json_pointer/operator_ne/index.md) compare: not equal
## Version history
- Added in version 3.11.2.
+4 -1
View File
@@ -26,6 +26,8 @@ operator string_t() const
This function is deprecated in favor of [`to_string`](to_string.md) and will be removed in a future major version
release.
See the [migration guide](../../integration/migration_guide.md#json-pointers) for how to update existing code.
## Examples
??? example
@@ -44,7 +46,8 @@ operator string_t() const
## See also
- [string_t](../basic_json/string_t.md)- type for strings
- [to_string](to_string.md) return a string representation of the JSON pointer
- [string_t](../basic_json/string_t.md) - type for strings
## Version history
@@ -1,9 +1,9 @@
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</code></pre></div> <p>Return a string representation of the <abbr title="JavaScript Object Notation">JSON</abbr> pointer.</p> <h2 id=return-value>Return value<a class=headerlink href=#return-value title="Permanent link">&para;</a></h2> <p>A string representation of the <abbr title="JavaScript Object Notation">JSON</abbr> pointer</p> <h2 id=possible-implementation>Possible implementation<a class=headerlink href=#possible-implementation title="Permanent link">&para;</a></h2> <div class=highlight><pre><span></span><code><span class=k>operator</span><span class=w> </span><span class=n>string_t</span><span class=p>()</span><span class=w> </span><span class=k>const</span>
<span class=p>{</span>
<span class=w> </span><span class=k>return</span><span class=w> </span><span class=n>to_string</span><span class=p>();</span>
<span class=p>}</span>
</code></pre></div> <h2 id=notes>Notes<a class=headerlink href=#notes title="Permanent link">&para;</a></h2> <div class="admonition warning"> <p class=admonition-title>Deprecation</p> <p>This function is deprecated in favor of <a href=../to_string/ ><code>to_string</code></a> and will be removed in a future major version release.</p> </div> <h2 id=examples>Examples<a class=headerlink href=#examples title="Permanent link">&para;</a></h2> <details class=example> <summary>Example</summary> <p>The example shows how <abbr title="JavaScript Object Notation">JSON</abbr> Pointers can be implicitly converted to strings.</p> <div class=highlight><pre><span></span><code><span class=cp>#include</span><span class=w> </span><span class=cpf>&lt;iostream&gt;</span>
</code></pre></div> <h2 id=notes>Notes<a class=headerlink href=#notes title="Permanent link">&para;</a></h2> <div class="admonition warning"> <p class=admonition-title>Deprecation</p> <p>This function is deprecated in favor of <a href=../to_string/ ><code>to_string</code></a> and will be removed in a future major version release.</p> <p>See the <a href=../../../integration/migration_guide/#json-pointers>migration guide</a> for how to update existing code.</p> </div> <h2 id=examples>Examples<a class=headerlink href=#examples title="Permanent link">&para;</a></h2> <details class=example> <summary>Example</summary> <p>The example shows how <abbr title="JavaScript Object Notation">JSON</abbr> Pointers can be implicitly converted to strings.</p> <div class=highlight><pre><span></span><code><span class=cp>#include</span><span class=w> </span><span class=cpf>&lt;iostream&gt;</span>
<span class=cp>#include</span><span class=w> </span><span class=cpf>&lt;nlohmann/json.hpp&gt;</span>
<span class=k>using</span><span class=w> </span><span class=n>json</span><span class=w> </span><span class=o>=</span><span class=w> </span><span class=n>nlohmann</span><span class=o>::</span><span class=n>json</span><span class=p>;</span>
@@ -24,4 +24,4 @@
<span class=p>}</span>
</code></pre></div> <p>Output:</p> <div class=highlight><pre><span></span><code><span class=err>/</span><span class=kc>f</span><span class=err>oo/</span><span class=mi>0</span>
<span class=err>/a~</span><span class=mi>1</span><span class=err>b</span>
</code></pre></div> </details> <h2 id=see-also>See also<a class=headerlink href=#see-also title="Permanent link">&para;</a></h2> <ul> <li><a href=../../basic_json/string_t/ >string_t</a>- type for strings</li> </ul> <h2 id=version-history>Version history<a class=headerlink href=#version-history title="Permanent link">&para;</a></h2> <ul> <li>Since version 2.0.0.</li> <li>Changed type to <code>string_t</code> and deprecated in version 3.11.0.</li> </ul> <!-- https://squidfunk.github.io/mkdocs-material/reference/tooltips/#adding-a-glossary --> <aside class=md-source-file> <span class=md-source-file__fact> <span class=md-icon title="Last update"> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M21 13.1c-.1 0-.3.1-.4.2l-1 1 2.1 2.1 1-1c.2-.2.2-.6 0-.8l-1.3-1.3c-.1-.1-.2-.2-.4-.2m-1.9 1.8-6.1 6V23h2.1l6.1-6.1zM12.5 7v5.2l4 2.4-1 1L11 13V7zM11 21.9c-5.1-.5-9-4.8-9-9.9C2 6.5 6.5 2 12 2c5.3 0 9.6 4.1 10 9.3-.3-.1-.6-.2-1-.2s-.7.1-1 .2C19.6 7.2 16.2 4 12 4c-4.4 0-8 3.6-8 8 0 4.1 3.1 7.5 7.1 7.9l-.1.2z"/></svg> </span> <span class="git-revision-date-localized-plugin git-revision-date-localized-plugin-date" title="October 2, 2026 09:23:55 UTC">October 2, 2026</span> </span> </aside> </article> </div> <script>var tabs=__md_get("__tabs");if(Array.isArray(tabs))e:for(var set of document.querySelectorAll(".tabbed-set")){var labels=set.querySelector(".tabbed-labels");for(var tab of tabs)for(var label of labels.getElementsByTagName("label"))if(label.innerText.trim()===tab){var input=document.getElementById(label.htmlFor);input.checked=!0;continue e}}</script> <script>var target=document.getElementById(location.hash.slice(1));target&&target.name&&(target.checked=target.name.startsWith("__tabbed_"))</script> </div> <button type=button class="md-top md-icon" data-md-component=top hidden> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M13 20h-2V8l-5.5 5.5-1.42-1.42L12 4.16l7.92 7.92-1.42 1.42L13 8z"/></svg> Back to top </button> </main> <footer class=md-footer> <div class="md-footer-meta md-typeset"> <div class="md-footer-meta__inner md-grid"> <div class=md-copyright> <div class=md-copyright__highlight> Copyright &copy; 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</code></pre></div> </details> <h2 id=see-also>See also<a class=headerlink href=#see-also title="Permanent link">&para;</a></h2> <ul> <li><a href=../to_string/ >to_string</a> return a string representation of the <abbr title="JavaScript Object Notation">JSON</abbr> pointer</li> <li><a href=../../basic_json/string_t/ >string_t</a> - type for strings</li> </ul> <h2 id=version-history>Version history<a class=headerlink href=#version-history title="Permanent link">&para;</a></h2> <ul> <li>Since version 2.0.0.</li> <li>Changed type to <code>string_t</code> and deprecated in version 3.11.0.</li> </ul> <!-- https://squidfunk.github.io/mkdocs-material/reference/tooltips/#adding-a-glossary --> <aside class=md-source-file> <span class=md-source-file__fact> <span class=md-icon title="Last update"> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M21 13.1c-.1 0-.3.1-.4.2l-1 1 2.1 2.1 1-1c.2-.2.2-.6 0-.8l-1.3-1.3c-.1-.1-.2-.2-.4-.2m-1.9 1.8-6.1 6V23h2.1l6.1-6.1zM12.5 7v5.2l4 2.4-1 1L11 13V7zM11 21.9c-5.1-.5-9-4.8-9-9.9C2 6.5 6.5 2 12 2c5.3 0 9.6 4.1 10 9.3-.3-.1-.6-.2-1-.2s-.7.1-1 .2C19.6 7.2 16.2 4 12 4c-4.4 0-8 3.6-8 8 0 4.1 3.1 7.5 7.1 7.9l-.1.2z"/></svg> </span> <span class="git-revision-date-localized-plugin git-revision-date-localized-plugin-date" title="October 2, 2026 09:32:15 UTC">October 2, 2026</span> </span> </aside> </article> </div> <script>var tabs=__md_get("__tabs");if(Array.isArray(tabs))e:for(var set of document.querySelectorAll(".tabbed-set")){var labels=set.querySelector(".tabbed-labels");for(var tab of tabs)for(var label of labels.getElementsByTagName("label"))if(label.innerText.trim()===tab){var input=document.getElementById(label.htmlFor);input.checked=!0;continue e}}</script> <script>var target=document.getElementById(location.hash.slice(1));target&&target.name&&(target.checked=target.name.startsWith("__tabbed_"))</script> </div> <button type=button class="md-top md-icon" data-md-component=top hidden> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M13 20h-2V8l-5.5 5.5-1.42-1.42L12 4.16l7.92 7.92-1.42 1.42L13 8z"/></svg> Back to top </button> </main> <footer class=md-footer> <div class="md-footer-meta md-typeset"> <div class="md-footer-meta__inner md-grid"> <div class=md-copyright> <div class=md-copyright__highlight> Copyright &copy; 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+4 -1
View File
@@ -25,6 +25,8 @@ Deprecation
This function is deprecated in favor of [`to_string`](https://json.nlohmann.me/api/json_pointer/to_string/index.md) and will be removed in a future major version release.
See the [migration guide](https://json.nlohmann.me/integration/migration_guide/#json-pointers) for how to update existing code.
## Examples
Example
@@ -62,7 +64,8 @@ Output:
## See also
- [string_t](https://json.nlohmann.me/api/basic_json/string_t/index.md)- type for strings
- [to_string](https://json.nlohmann.me/api/json_pointer/to_string/index.md) return a string representation of the JSON pointer
- [string_t](https://json.nlohmann.me/api/basic_json/string_t/index.md) - type for strings
## Version history
+2 -2
View File
@@ -1,4 +1,4 @@
<!doctype html><html lang=en class=no-js> <head><meta charset=utf-8><meta name=viewport content="width=device-width,initial-scale=1"><meta name=author content="Niels Lohmann"><link href="https://json.nlohmann.me/api/json_pointer/parent_pointer/" rel="canonical"><link href=../operator_slasheq/ rel=prev><link href=../pop_back/ rel=next><link rel=icon href=../../../assets/images/favicon.png><meta name=generator content="mkdocs-1.6.1, mkdocs-material-9.7.7"><title>parent_pointer - JSON for Modern C++</title><link rel=stylesheet href=../../../assets/stylesheets/main.ec1eaa64.min.css><link rel=stylesheet href=../../../assets/stylesheets/palette.ab4e12ef.min.css><link rel="stylesheet" href="../../../assets/external/fonts.googleapis.com/css.61a430c9.css"><style>:root{--md-text-font:"Roboto";--md-code-font:"JetBrains Mono"}</style><link rel=stylesheet href=../../../css/custom.css><script>__md_scope=new 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<!doctype html><html lang=en class=no-js> <head><meta charset=utf-8><meta name=viewport content="width=device-width,initial-scale=1"><meta name=author content="Niels Lohmann"><link href="https://json.nlohmann.me/api/json_pointer/parent_pointer/" rel="canonical"><link href=../operator_slasheq/ rel=prev><link href=../pop_back/ rel=next><link rel=icon href=../../../assets/images/favicon.png><meta name=generator content="mkdocs-1.6.1, mkdocs-material-9.7.7"><title>parent_pointer - JSON for Modern C++</title><link rel=stylesheet href=../../../assets/stylesheets/main.ec1eaa64.min.css><link rel=stylesheet href=../../../assets/stylesheets/palette.ab4e12ef.min.css><link rel="stylesheet" href="../../../assets/external/fonts.googleapis.com/css.61a430c9.css"><style>:root{--md-text-font:"Roboto";--md-code-font:"JetBrains Mono"}</style><link rel=stylesheet href=../../../css/custom.css><script>__md_scope=new 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data-md-component=logo> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M12 8a3 3 0 0 0 3-3 3 3 0 0 0-3-3 3 3 0 0 0-3 3 3 3 0 0 0 3 3m0 3.54C9.64 9.35 6.5 8 3 8v11c3.5 0 6.64 1.35 9 3.54 2.36-2.19 5.5-3.54 9-3.54V8c-3.5 0-6.64 1.35-9 3.54"/></svg> </a> <label class="md-header__button md-icon" for=__drawer> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M3 6h18v2H3zm0 5h18v2H3zm0 5h18v2H3z"/></svg> </label> <div class=md-header__title data-md-component=header-title> <div class=md-header__ellipsis> <div class=md-header__topic> <span class=md-ellipsis> JSON for Modern C++ </span> </div> <div class=md-header__topic data-md-component=header-topic> <span class=md-ellipsis> parent_pointer </span> </div> </div> </div> <form class=md-header__option data-md-component=palette> <input class=md-option data-md-color-media="(prefers-color-scheme: light)" data-md-color-scheme=default data-md-color-primary=indigo data-md-color-accent=indigo aria-label="Switch to 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</code></pre></div> <p>Returns the parent of this <abbr title="JavaScript Object Notation">JSON</abbr> pointer.</p> <h2 id=return-value>Return value<a class=headerlink href=#return-value title="Permanent link">&para;</a></h2> <p>Parent of this <abbr title="JavaScript Object Notation">JSON</abbr> pointer; in case this <abbr title="JavaScript Object Notation">JSON</abbr> pointer is the root, the root itself is returned.</p> <h2 id=exception-safety>Exception safety<a class=headerlink href=#exception-safety title="Permanent link">&para;</a></h2> <p>No-throw guarantee: this function never throws exceptions.</p> <h2 id=complexity>Complexity<a class=headerlink href=#complexity title="Permanent link">&para;</a></h2> <p>Linear in the length of the <abbr title="JavaScript Object Notation">JSON</abbr> pointer.</p> <h2 id=examples>Examples<a class=headerlink href=#examples title="Permanent link">&para;</a></h2> <details class=example> <summary>Example</summary> <p>The example shows the result of <code>parent_pointer</code> for different <abbr title="JavaScript Object Notation">JSON</abbr> Pointers.</p> <div class=highlight><pre><span></span><code><span class=cp>#include</span><span class=w> </span><span class=cpf>&lt;iostream&gt;</span>
<span class=cp>#include</span><span class=w> </span><span class=cpf>&lt;nlohmann/json.hpp&gt;</span>
@@ -20,4 +20,4 @@
</code></pre></div> <p>Output:</p> <div class=highlight><pre><span></span><code><span class=err>pare</span><span class=kc>nt</span><span class=w> </span><span class=err>o</span><span class=kc>f</span><span class=w> </span><span class=s2>""</span><span class=w> </span><span class=err>is</span><span class=w> </span><span class=s2>""</span>
<span class=err>pare</span><span class=kc>nt</span><span class=w> </span><span class=err>o</span><span class=kc>f</span><span class=w> </span><span class=s2>"/foo"</span><span class=w> </span><span class=err>is</span><span class=w> </span><span class=s2>""</span>
<span class=err>pare</span><span class=kc>nt</span><span class=w> </span><span class=err>o</span><span class=kc>f</span><span class=w> </span><span class=s2>"/foo/0"</span><span class=w> </span><span class=err>is</span><span class=w> </span><span class=s2>"/foo"</span>
</code></pre></div> </details> <h2 id=see-also>See also<a class=headerlink href=#see-also title="Permanent link">&para;</a></h2> <ul> <li><a href=../pop_back/ >pop_back</a> remove the last reference token</li> <li><a href=../back/ >back</a> return the last reference token</li> </ul> <h2 id=version-history>Version history<a class=headerlink href=#version-history title="Permanent link">&para;</a></h2> <p>Added in version 3.6.0.</p> <!-- https://squidfunk.github.io/mkdocs-material/reference/tooltips/#adding-a-glossary --> <aside class=md-source-file> <span class=md-source-file__fact> <span class=md-icon title="Last update"> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M21 13.1c-.1 0-.3.1-.4.2l-1 1 2.1 2.1 1-1c.2-.2.2-.6 0-.8l-1.3-1.3c-.1-.1-.2-.2-.4-.2m-1.9 1.8-6.1 6V23h2.1l6.1-6.1zM12.5 7v5.2l4 2.4-1 1L11 13V7zM11 21.9c-5.1-.5-9-4.8-9-9.9C2 6.5 6.5 2 12 2c5.3 0 9.6 4.1 10 9.3-.3-.1-.6-.2-1-.2s-.7.1-1 .2C19.6 7.2 16.2 4 12 4c-4.4 0-8 3.6-8 8 0 4.1 3.1 7.5 7.1 7.9l-.1.2z"/></svg> </span> <span class="git-revision-date-localized-plugin git-revision-date-localized-plugin-date" title="October 2, 2026 09:23:55 UTC">October 2, 2026</span> </span> </aside> </article> </div> <script>var tabs=__md_get("__tabs");if(Array.isArray(tabs))e:for(var set of document.querySelectorAll(".tabbed-set")){var labels=set.querySelector(".tabbed-labels");for(var tab of tabs)for(var label of labels.getElementsByTagName("label"))if(label.innerText.trim()===tab){var input=document.getElementById(label.htmlFor);input.checked=!0;continue e}}</script> <script>var target=document.getElementById(location.hash.slice(1));target&&target.name&&(target.checked=target.name.startsWith("__tabbed_"))</script> </div> <button type=button class="md-top md-icon" data-md-component=top hidden> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M13 20h-2V8l-5.5 5.5-1.42-1.42L12 4.16l7.92 7.92-1.42 1.42L13 8z"/></svg> Back to top </button> </main> <footer class=md-footer> <div class="md-footer-meta md-typeset"> <div class="md-footer-meta__inner md-grid"> <div class=md-copyright> <div class=md-copyright__highlight> Copyright &copy; 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</code></pre></div> </details> <h2 id=see-also>See also<a class=headerlink href=#see-also title="Permanent link">&para;</a></h2> <ul> <li><a href=../pop_back/ >pop_back</a> remove the last reference token</li> <li><a href=../back/ >back</a> return the last reference token</li> </ul> <h2 id=version-history>Version history<a class=headerlink href=#version-history title="Permanent link">&para;</a></h2> <p>Added in version 3.6.0.</p> <!-- https://squidfunk.github.io/mkdocs-material/reference/tooltips/#adding-a-glossary --> <aside class=md-source-file> <span class=md-source-file__fact> <span class=md-icon title="Last update"> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M21 13.1c-.1 0-.3.1-.4.2l-1 1 2.1 2.1 1-1c.2-.2.2-.6 0-.8l-1.3-1.3c-.1-.1-.2-.2-.4-.2m-1.9 1.8-6.1 6V23h2.1l6.1-6.1zM12.5 7v5.2l4 2.4-1 1L11 13V7zM11 21.9c-5.1-.5-9-4.8-9-9.9C2 6.5 6.5 2 12 2c5.3 0 9.6 4.1 10 9.3-.3-.1-.6-.2-1-.2s-.7.1-1 .2C19.6 7.2 16.2 4 12 4c-4.4 0-8 3.6-8 8 0 4.1 3.1 7.5 7.1 7.9l-.1.2z"/></svg> </span> <span class="git-revision-date-localized-plugin git-revision-date-localized-plugin-date" title="June 29, 2026 20:15:18 UTC">June 29, 2026</span> </span> </aside> </article> </div> <script>var tabs=__md_get("__tabs");if(Array.isArray(tabs))e:for(var set of document.querySelectorAll(".tabbed-set")){var labels=set.querySelector(".tabbed-labels");for(var tab of tabs)for(var label of labels.getElementsByTagName("label"))if(label.innerText.trim()===tab){var input=document.getElementById(label.htmlFor);input.checked=!0;continue e}}</script> <script>var target=document.getElementById(location.hash.slice(1));target&&target.name&&(target.checked=target.name.startsWith("__tabbed_"))</script> </div> <button type=button class="md-top md-icon" data-md-component=top hidden> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M13 20h-2V8l-5.5 5.5-1.42-1.42L12 4.16l7.92 7.92-1.42 1.42L13 8z"/></svg> Back to top </button> </main> <footer class=md-footer> <div class="md-footer-meta md-typeset"> <div class="md-footer-meta__inner md-grid"> <div class=md-copyright> <div class=md-copyright__highlight> Copyright &copy; 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+10
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@@ -6,6 +6,10 @@ void pop_back();
Remove the last reference token.
## Exception safety
Strong exception safety: if an exception occurs, the original value stays intact.
## Exceptions
Throws [out_of_range.405](../../home/exceptions.md#jsonexceptionout_of_range405) if the JSON pointer has no parent.
@@ -30,6 +34,12 @@ Constant.
--8<-- "examples/json_pointer__pop_back.output"
```
## See also
- [back](back.md) return last reference token
- [push_back](push_back.md) append an unescaped token at the end of the pointer
- [parent_pointer](parent_pointer.md) returns the parent of this JSON pointer
## Version history
Added in version 3.6.0.
+3 -3
View File
@@ -1,5 +1,5 @@
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data-md-component=logo> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M12 8a3 3 0 0 0 3-3 3 3 0 0 0-3-3 3 3 0 0 0-3 3 3 3 0 0 0 3 3m0 3.54C9.64 9.35 6.5 8 3 8v11c3.5 0 6.64 1.35 9 3.54 2.36-2.19 5.5-3.54 9-3.54V8c-3.5 0-6.64 1.35-9 3.54"/></svg> </a> <label class="md-header__button md-icon" for=__drawer> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M3 6h18v2H3zm0 5h18v2H3zm0 5h18v2H3z"/></svg> </label> <div class=md-header__title data-md-component=header-title> <div class=md-header__ellipsis> <div class=md-header__topic> <span class=md-ellipsis> JSON for Modern C++ </span> </div> <div class=md-header__topic data-md-component=header-topic> <span class=md-ellipsis> pop_back </span> </div> </div> </div> <form class=md-header__option data-md-component=palette> <input class=md-option data-md-color-media="(prefers-color-scheme: light)" data-md-color-scheme=default data-md-color-primary=indigo data-md-color-accent=indigo aria-label="Switch to dark 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</code></pre></div> <p>Remove the last reference token.</p> <h2 id=exceptions>Exceptions<a class=headerlink href=#exceptions title="Permanent link">&para;</a></h2> <p>Throws <a href=../../../home/exceptions/#jsonexceptionout_of_range405>out_of_range.405</a> if the <abbr title="JavaScript Object Notation">JSON</abbr> pointer has no parent.</p> <h2 id=complexity>Complexity<a class=headerlink href=#complexity title="Permanent link">&para;</a></h2> <p>Constant.</p> <h2 id=examples>Examples<a class=headerlink href=#examples title="Permanent link">&para;</a></h2> <details class=example> <summary>Example</summary> <p>The example shows the usage of <code>pop_back</code>.</p> <div class=highlight><pre><span></span><code><span class=cp>#include</span><span class=w> </span><span class=cpf>&lt;iostream&gt;</span>
<!doctype html><html lang=en class=no-js> <head><meta charset=utf-8><meta name=viewport content="width=device-width,initial-scale=1"><meta name=author content="Niels Lohmann"><link href="https://json.nlohmann.me/api/json_pointer/pop_back/" rel="canonical"><link href=../parent_pointer/ rel=prev><link href=../pop_front/ rel=next><link rel=icon href=../../../assets/images/favicon.png><meta name=generator content="mkdocs-1.6.1, mkdocs-material-9.7.7"><title>pop_back - JSON for Modern C++</title><link rel=stylesheet href=../../../assets/stylesheets/main.ec1eaa64.min.css><link rel=stylesheet href=../../../assets/stylesheets/palette.ab4e12ef.min.css><link rel="stylesheet" href="../../../assets/external/fonts.googleapis.com/css.61a430c9.css"><style>:root{--md-text-font:"Roboto";--md-code-font:"JetBrains Mono"}</style><link rel=stylesheet href=../../../css/custom.css><script>__md_scope=new 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data-md-component=logo> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M12 8a3 3 0 0 0 3-3 3 3 0 0 0-3-3 3 3 0 0 0-3 3 3 3 0 0 0 3 3m0 3.54C9.64 9.35 6.5 8 3 8v11c3.5 0 6.64 1.35 9 3.54 2.36-2.19 5.5-3.54 9-3.54V8c-3.5 0-6.64 1.35-9 3.54"/></svg> </a> <label class="md-header__button md-icon" for=__drawer> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M3 6h18v2H3zm0 5h18v2H3zm0 5h18v2H3z"/></svg> </label> <div class=md-header__title data-md-component=header-title> <div class=md-header__ellipsis> <div class=md-header__topic> <span class=md-ellipsis> JSON for Modern C++ </span> </div> <div class=md-header__topic data-md-component=header-topic> <span class=md-ellipsis> pop_back </span> </div> </div> </div> <form class=md-header__option data-md-component=palette> <input class=md-option data-md-color-media="(prefers-color-scheme: light)" data-md-color-scheme=default data-md-color-primary=indigo data-md-color-accent=indigo aria-label="Switch to dark mode" type=radio name=__palette id=__palette_0> <label class="md-header__button md-icon" title="Switch to dark mode" for=__palette_1 hidden> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M12 8a4 4 0 0 0-4 4 4 4 0 0 0 4 4 4 4 0 0 0 4-4 4 4 0 0 0-4-4m0 10a6 6 0 0 1-6-6 6 6 0 0 1 6-6 6 6 0 0 1 6 6 6 6 0 0 1-6 6m8-9.31V4h-4.69L12 .69 8.69 4H4v4.69L.69 12 4 15.31V20h4.69L12 23.31 15.31 20H20v-4.69L23.31 12z"/></svg> </label> <input class=md-option data-md-color-media="(prefers-color-scheme: dark)" data-md-color-scheme=slate data-md-color-primary=indigo data-md-color-accent=indigo aria-label="Switch to light mode" type=radio name=__palette id=__palette_1> <label class="md-header__button md-icon" title="Switch to light mode" for=__palette_0 hidden> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M12 18c-.89 0-1.74-.2-2.5-.55C11.56 16.5 13 14.42 13 12s-1.44-4.5-3.5-5.45C10.26 6.2 11.11 6 12 6a6 6 0 0 1 6 6 6 6 0 0 1-6 6m8-9.31V4h-4.69L12 .69 8.69 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1.5-5-5v-.79l-.27-.27A6.52 6.52 0 0 1 9.5 16 6.5 6.5 0 0 1 3 9.5 6.5 6.5 0 0 1 9.5 3m0 2C7 5 5 7 5 9.5S7 14 9.5 14 14 12 14 9.5 12 5 9.Line truncated
</code></pre></div> <p>Remove the last reference token.</p> <h2 id=exception-safety>Exception safety<a class=headerlink href=#exception-safety title="Permanent link">&para;</a></h2> <p>Strong exception safety: if an exception occurs, the original value stays intact.</p> <h2 id=exceptions>Exceptions<a class=headerlink href=#exceptions title="Permanent link">&para;</a></h2> <p>Throws <a href=../../../home/exceptions/#jsonexceptionout_of_range405>out_of_range.405</a> if the <abbr title="JavaScript Object Notation">JSON</abbr> pointer has no parent.</p> <h2 id=complexity>Complexity<a class=headerlink href=#complexity title="Permanent link">&para;</a></h2> <p>Constant.</p> <h2 id=examples>Examples<a class=headerlink href=#examples title="Permanent link">&para;</a></h2> <details class=example> <summary>Example</summary> <p>The example shows the usage of <code>pop_back</code>.</p> <div class=highlight><pre><span></span><code><span class=cp>#include</span><span class=w> </span><span class=cpf>&lt;iostream&gt;</span>
<span class=cp>#include</span><span class=w> </span><span class=cpf>&lt;nlohmann/json.hpp&gt;</span>
<span class=k>using</span><span class=w> </span><span class=n>json</span><span class=w> </span><span class=o>=</span><span class=w> </span><span class=n>nlohmann</span><span class=o>::</span><span class=n>json</span><span class=p>;</span>
@@ -24,4 +24,4 @@
<span class=s2>"/foo/bar"</span>
<span class=s2>"/foo"</span>
<span class=s2>""</span>
</code></pre></div> </details> <h2 id=version-history>Version history<a class=headerlink href=#version-history title="Permanent link">&para;</a></h2> <p>Added in version 3.6.0.</p> <!-- https://squidfunk.github.io/mkdocs-material/reference/tooltips/#adding-a-glossary --> <aside class=md-source-file> <span class=md-source-file__fact> <span class=md-icon title="Last update"> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M21 13.1c-.1 0-.3.1-.4.2l-1 1 2.1 2.1 1-1c.2-.2.2-.6 0-.8l-1.3-1.3c-.1-.1-.2-.2-.4-.2m-1.9 1.8-6.1 6V23h2.1l6.1-6.1zM12.5 7v5.2l4 2.4-1 1L11 13V7zM11 21.9c-5.1-.5-9-4.8-9-9.9C2 6.5 6.5 2 12 2c5.3 0 9.6 4.1 10 9.3-.3-.1-.6-.2-1-.2s-.7.1-1 .2C19.6 7.2 16.2 4 12 4c-4.4 0-8 3.6-8 8 0 4.1 3.1 7.5 7.1 7.9l-.1.2z"/></svg> </span> <span class="git-revision-date-localized-plugin git-revision-date-localized-plugin-date" title="October 2, 2026 09:23:55 UTC">October 2, 2026</span> </span> </aside> </article> </div> <script>var tabs=__md_get("__tabs");if(Array.isArray(tabs))e:for(var set of document.querySelectorAll(".tabbed-set")){var labels=set.querySelector(".tabbed-labels");for(var tab of tabs)for(var label of labels.getElementsByTagName("label"))if(label.innerText.trim()===tab){var input=document.getElementById(label.htmlFor);input.checked=!0;continue e}}</script> <script>var target=document.getElementById(location.hash.slice(1));target&&target.name&&(target.checked=target.name.startsWith("__tabbed_"))</script> </div> <button type=button class="md-top md-icon" data-md-component=top hidden> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M13 20h-2V8l-5.5 5.5-1.42-1.42L12 4.16l7.92 7.92-1.42 1.42L13 8z"/></svg> Back to top </button> </main> <footer class=md-footer> <div class="md-footer-meta md-typeset"> <div class="md-footer-meta__inner md-grid"> <div class=md-copyright> <div class=md-copyright__highlight> Copyright &copy; 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</code></pre></div> </details> <h2 id=see-also>See also<a class=headerlink href=#see-also title="Permanent link">&para;</a></h2> <ul> <li><a href=../back/ >back</a> return last reference token</li> <li><a href=../push_back/ >push_back</a> append an unescaped token at the end of the pointer</li> <li><a href=../parent_pointer/ >parent_pointer</a> returns the parent of this <abbr title="JavaScript Object Notation">JSON</abbr> pointer</li> </ul> <h2 id=version-history>Version history<a class=headerlink href=#version-history title="Permanent link">&para;</a></h2> <p>Added in version 3.6.0.</p> <!-- https://squidfunk.github.io/mkdocs-material/reference/tooltips/#adding-a-glossary --> <aside class=md-source-file> <span class=md-source-file__fact> <span class=md-icon title="Last update"> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M21 13.1c-.1 0-.3.1-.4.2l-1 1 2.1 2.1 1-1c.2-.2.2-.6 0-.8l-1.3-1.3c-.1-.1-.2-.2-.4-.2m-1.9 1.8-6.1 6V23h2.1l6.1-6.1zM12.5 7v5.2l4 2.4-1 1L11 13V7zM11 21.9c-5.1-.5-9-4.8-9-9.9C2 6.5 6.5 2 12 2c5.3 0 9.6 4.1 10 9.3-.3-.1-.6-.2-1-.2s-.7.1-1 .2C19.6 7.2 16.2 4 12 4c-4.4 0-8 3.6-8 8 0 4.1 3.1 7.5 7.1 7.9l-.1.2z"/></svg> </span> <span class="git-revision-date-localized-plugin git-revision-date-localized-plugin-date" title="October 2, 2026 09:32:15 UTC">October 2, 2026</span> </span> </aside> </article> </div> <script>var tabs=__md_get("__tabs");if(Array.isArray(tabs))e:for(var set of document.querySelectorAll(".tabbed-set")){var labels=set.querySelector(".tabbed-labels");for(var tab of tabs)for(var label of labels.getElementsByTagName("label"))if(label.innerText.trim()===tab){var input=document.getElementById(label.htmlFor);input.checked=!0;continue e}}</script> <script>var target=document.getElementById(location.hash.slice(1));target&&target.name&&(target.checked=target.name.startsWith("__tabbed_"))</script> </div> <button type=button class="md-top md-icon" data-md-component=top hidden> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M13 20h-2V8l-5.5 5.5-1.42-1.42L12 4.16l7.92 7.92-1.42 1.42L13 8z"/></svg> Back to top </button> </main> <footer class=md-footer> <div class="md-footer-meta md-typeset"> <div class="md-footer-meta__inner md-grid"> <div class=md-copyright> <div class=md-copyright__highlight> Copyright &copy; 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+10
View File
@@ -6,6 +6,10 @@ void pop_back();
Remove the last reference token.
## Exception safety
Strong exception safety: if an exception occurs, the original value stays intact.
## Exceptions
Throws [out_of_range.405](https://json.nlohmann.me/home/exceptions/#jsonexceptionout_of_range405) if the JSON pointer has no parent.
@@ -53,6 +57,12 @@ Output:
""
```
## See also
- [back](https://json.nlohmann.me/api/json_pointer/back/index.md) return last reference token
- [push_back](https://json.nlohmann.me/api/json_pointer/push_back/index.md) append an unescaped token at the end of the pointer
- [parent_pointer](https://json.nlohmann.me/api/json_pointer/parent_pointer/index.md) returns the parent of this JSON pointer
## Version history
Added in version 3.6.0.
+9
View File
@@ -6,6 +6,10 @@ void pop_front();
Remove the first reference token.
## Exception safety
Strong exception safety: if an exception occurs, the original value stays intact.
## Exceptions
Throws [out_of_range.405](../../home/exceptions.md#jsonexceptionout_of_range405) if the JSON pointer has no parent.
@@ -30,6 +34,11 @@ Linear in the number of reference tokens in the `json_pointer`.
--8<-- "examples/json_pointer__pop_front.output"
```
## See also
- [front](front.md) return first reference token
- [push_front](push_front.md) append an unescaped token at the start of the pointer
## Version history
- Added in version 3.13.0.
+3 -3
View File
@@ -1,5 +1,5 @@
<!doctype html><html lang=en class=no-js> <head><meta charset=utf-8><meta name=viewport content="width=device-width,initial-scale=1"><meta name=author content="Niels Lohmann"><link href="https://json.nlohmann.me/api/json_pointer/pop_front/" rel="canonical"><link href=../pop_back/ rel=prev><link href=../push_back/ rel=next><link rel=icon href=../../../assets/images/favicon.png><meta name=generator content="mkdocs-1.6.1, mkdocs-material-9.7.7"><title>pop_front - JSON for Modern C++</title><link rel=stylesheet href=../../../assets/stylesheets/main.ec1eaa64.min.css><link rel=stylesheet href=../../../assets/stylesheets/palette.ab4e12ef.min.css><link rel="stylesheet" href="../../../assets/external/fonts.googleapis.com/css.61a430c9.css"><style>:root{--md-text-font:"Roboto";--md-code-font:"JetBrains Mono"}</style><link rel=stylesheet href=../../../css/custom.css><script>__md_scope=new 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data-md-component=logo> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M12 8a3 3 0 0 0 3-3 3 3 0 0 0-3-3 3 3 0 0 0-3 3 3 3 0 0 0 3 3m0 3.54C9.64 9.35 6.5 8 3 8v11c3.5 0 6.64 1.35 9 3.54 2.36-2.19 5.5-3.54 9-3.54V8c-3.5 0-6.64 1.35-9 3.54"/></svg> </a> <label class="md-header__button md-icon" for=__drawer> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M3 6h18v2H3zm0 5h18v2H3zm0 5h18v2H3z"/></svg> </label> <div class=md-header__title data-md-component=header-title> <div class=md-header__ellipsis> <div class=md-header__topic> <span class=md-ellipsis> JSON for Modern C++ </span> </div> <div class=md-header__topic data-md-component=header-topic> <span class=md-ellipsis> pop_front </span> </div> </div> </div> <form class=md-header__option data-md-component=palette> <input class=md-option data-md-color-media="(prefers-color-scheme: light)" data-md-color-scheme=default data-md-color-primary=indigo data-md-color-accent=indigo aria-label="Switch to dark 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</code></pre></div> <p>Remove the first reference token.</p> <h2 id=exceptions>Exceptions<a class=headerlink href=#exceptions title="Permanent link">&para;</a></h2> <p>Throws <a href=../../../home/exceptions/#jsonexceptionout_of_range405>out_of_range.405</a> if the <abbr title="JavaScript Object Notation">JSON</abbr> pointer has no parent.</p> <h2 id=complexity>Complexity<a class=headerlink href=#complexity title="Permanent link">&para;</a></h2> <p>Linear in the number of reference tokens in the <code>json_pointer</code>.</p> <h2 id=examples>Examples<a class=headerlink href=#examples title="Permanent link">&para;</a></h2> <details class=example> <summary>Example</summary> <p>The example shows the usage of <code>pop_front</code>.</p> <div class=highlight><pre><span></span><code><span class=cp>#include</span><span class=w> </span><span class=cpf>&lt;iostream&gt;</span>
<!doctype html><html lang=en class=no-js> <head><meta charset=utf-8><meta name=viewport content="width=device-width,initial-scale=1"><meta name=author content="Niels Lohmann"><link href="https://json.nlohmann.me/api/json_pointer/pop_front/" rel="canonical"><link href=../pop_back/ rel=prev><link href=../push_back/ rel=next><link rel=icon href=../../../assets/images/favicon.png><meta name=generator content="mkdocs-1.6.1, mkdocs-material-9.7.7"><title>pop_front - JSON for Modern C++</title><link rel=stylesheet href=../../../assets/stylesheets/main.ec1eaa64.min.css><link rel=stylesheet href=../../../assets/stylesheets/palette.ab4e12ef.min.css><link rel="stylesheet" href="../../../assets/external/fonts.googleapis.com/css.61a430c9.css"><style>:root{--md-text-font:"Roboto";--md-code-font:"JetBrains Mono"}</style><link rel=stylesheet href=../../../css/custom.css><script>__md_scope=new URL("../../..",location),__md_hash=e=>[...e].reduce(((e,_)=>(e<<5)-e+_.charCodeAt(0)),0),__md_get=(e,_=localStorage,t=__md_scope)=>JSON.parse(_.getItem(t.pathname+"."+e)),__md_set=(e,_,t=localStorage,a=__md_scope)=>{try{t.setItem(a.pathname+"."+e,JSON.stringify(_))}catch(e){}}</script></head> <body dir=ltr data-md-color-scheme=default data-md-color-primary=indigo data-md-color-accent=indigo> <input class=md-toggle data-md-toggle=drawer type=checkbox id=__drawer autocomplete=off> <input class=md-toggle data-md-toggle=search type=checkbox id=__search autocomplete=off> <label class=md-overlay for=__drawer></label> <div data-md-component=skip> <a href=#nlohmannjson_pointerpop_front class=md-skip> Skip to content </a> </div> <div data-md-component=announce> </div> <header class=md-header data-md-component=header> <nav class="md-header__inner md-grid" aria-label=Header> <a href=../../.. title="JSON for Modern C++" class="md-header__button md-logo" aria-label="JSON for Modern C++" data-md-component=logo> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M12 8a3 3 0 0 0 3-3 3 3 0 0 0-3-3 3 3 0 0 0-3 3 3 3 0 0 0 3 3m0 3.54C9.64 9.35 6.5 8 3 8v11c3.5 0 6.64 1.35 9 3.54 2.36-2.19 5.5-3.54 9-3.54V8c-3.5 0-6.64 1.35-9 3.54"/></svg> </a> <label class="md-header__button md-icon" for=__drawer> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M3 6h18v2H3zm0 5h18v2H3zm0 5h18v2H3z"/></svg> </label> <div class=md-header__title data-md-component=header-title> <div class=md-header__ellipsis> <div class=md-header__topic> <span class=md-ellipsis> JSON for Modern C++ </span> </div> <div class=md-header__topic data-md-component=header-topic> <span class=md-ellipsis> pop_front </span> </div> </div> </div> <form class=md-header__option data-md-component=palette> <input class=md-option data-md-color-media="(prefers-color-scheme: light)" data-md-color-scheme=default data-md-color-primary=indigo data-md-color-accent=indigo aria-label="Switch to dark 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4H4v4.69L.69 12 4 15.31V20h4.69L12 23.31 15.31 20H20v-4.69L23.31 12z"/></svg> </label> </form> <script>var palette=__md_get("__palette");if(palette&&palette.color){if("(prefers-color-scheme)"===palette.color.media){var media=matchMedia("(prefers-color-scheme: light)"),input=document.querySelector(media.matches?"[data-md-color-media='(prefers-color-scheme: light)']":"[data-md-color-media='(prefers-color-scheme: dark)']");palette.color.media=input.getAttribute("data-md-color-media"),palette.color.scheme=input.getAttribute("data-md-color-scheme"),palette.color.primary=input.getAttribute("data-md-color-primary"),palette.color.accent=input.getAttribute("data-md-color-accent")}for(var[key,value]of Object.entries(palette.color))document.body.setAttribute("data-md-color-"+key,value)}</script> <label class="md-header__button md-icon" for=__search> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M9.5 3A6.5 6.5 0 0 1 16 9.5c0 1.61-.59 3.09-1.56 4.23l.27.27h.79l5 5-1.5 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</code></pre></div> <p>Remove the first reference token.</p> <h2 id=exception-safety>Exception safety<a class=headerlink href=#exception-safety title="Permanent link">&para;</a></h2> <p>Strong exception safety: if an exception occurs, the original value stays intact.</p> <h2 id=exceptions>Exceptions<a class=headerlink href=#exceptions title="Permanent link">&para;</a></h2> <p>Throws <a href=../../../home/exceptions/#jsonexceptionout_of_range405>out_of_range.405</a> if the <abbr title="JavaScript Object Notation">JSON</abbr> pointer has no parent.</p> <h2 id=complexity>Complexity<a class=headerlink href=#complexity title="Permanent link">&para;</a></h2> <p>Linear in the number of reference tokens in the <code>json_pointer</code>.</p> <h2 id=examples>Examples<a class=headerlink href=#examples title="Permanent link">&para;</a></h2> <details class=example> <summary>Example</summary> <p>The example shows the usage of <code>pop_front</code>.</p> <div class=highlight><pre><span></span><code><span class=cp>#include</span><span class=w> </span><span class=cpf>&lt;iostream&gt;</span>
<span class=cp>#include</span><span class=w> </span><span class=cpf>&lt;nlohmann/json.hpp&gt;</span>
<span class=k>using</span><span class=w> </span><span class=n>json</span><span class=w> </span><span class=o>=</span><span class=w> </span><span class=n>nlohmann</span><span class=o>::</span><span class=n>json</span><span class=p>;</span>
@@ -24,4 +24,4 @@
<span class=s2>"/bar/baz"</span>
<span class=s2>"/baz"</span>
<span class=s2>""</span>
</code></pre></div> </details> <h2 id=version-history>Version history<a class=headerlink href=#version-history title="Permanent link">&para;</a></h2> <ul> <li>Added in version 3.13.0.</li> </ul> <!-- https://squidfunk.github.io/mkdocs-material/reference/tooltips/#adding-a-glossary --> <aside class=md-source-file> <span class=md-source-file__fact> <span class=md-icon title="Last update"> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M21 13.1c-.1 0-.3.1-.4.2l-1 1 2.1 2.1 1-1c.2-.2.2-.6 0-.8l-1.3-1.3c-.1-.1-.2-.2-.4-.2m-1.9 1.8-6.1 6V23h2.1l6.1-6.1zM12.5 7v5.2l4 2.4-1 1L11 13V7zM11 21.9c-5.1-.5-9-4.8-9-9.9C2 6.5 6.5 2 12 2c5.3 0 9.6 4.1 10 9.3-.3-.1-.6-.2-1-.2s-.7.1-1 .2C19.6 7.2 16.2 4 12 4c-4.4 0-8 3.6-8 8 0 4.1 3.1 7.5 7.1 7.9l-.1.2z"/></svg> </span> <span class="git-revision-date-localized-plugin git-revision-date-localized-plugin-date" title="October 2, 2026 09:23:55 UTC">October 2, 2026</span> </span> </aside> </article> </div> <script>var tabs=__md_get("__tabs");if(Array.isArray(tabs))e:for(var set of document.querySelectorAll(".tabbed-set")){var labels=set.querySelector(".tabbed-labels");for(var tab of tabs)for(var label of labels.getElementsByTagName("label"))if(label.innerText.trim()===tab){var input=document.getElementById(label.htmlFor);input.checked=!0;continue e}}</script> <script>var target=document.getElementById(location.hash.slice(1));target&&target.name&&(target.checked=target.name.startsWith("__tabbed_"))</script> </div> <button type=button class="md-top md-icon" data-md-component=top hidden> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M13 20h-2V8l-5.5 5.5-1.42-1.42L12 4.16l7.92 7.92-1.42 1.42L13 8z"/></svg> Back to top </button> </main> <footer class=md-footer> <div class="md-footer-meta md-typeset"> <div class="md-footer-meta__inner md-grid"> <div class=md-copyright> <div class=md-copyright__highlight> Copyright &copy; 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</code></pre></div> </details> <h2 id=see-also>See also<a class=headerlink href=#see-also title="Permanent link">&para;</a></h2> <ul> <li><a href=../front/ >front</a> return first reference token</li> <li><a href=../push_front/ >push_front</a> append an unescaped token at the start of the pointer</li> </ul> <h2 id=version-history>Version history<a class=headerlink href=#version-history title="Permanent link">&para;</a></h2> <ul> <li>Added in version 3.13.0 <span class=unreleased-version title="Not part of a release yet; the latest release is 3.12.0.">unreleased</span>.</li> </ul> <!-- https://squidfunk.github.io/mkdocs-material/reference/tooltips/#adding-a-glossary --> <aside class=md-source-file> <span class=md-source-file__fact> <span class=md-icon title="Last update"> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M21 13.1c-.1 0-.3.1-.4.2l-1 1 2.1 2.1 1-1c.2-.2.2-.6 0-.8l-1.3-1.3c-.1-.1-.2-.2-.4-.2m-1.9 1.8-6.1 6V23h2.1l6.1-6.1zM12.5 7v5.2l4 2.4-1 1L11 13V7zM11 21.9c-5.1-.5-9-4.8-9-9.9C2 6.5 6.5 2 12 2c5.3 0 9.6 4.1 10 9.3-.3-.1-.6-.2-1-.2s-.7.1-1 .2C19.6 7.2 16.2 4 12 4c-4.4 0-8 3.6-8 8 0 4.1 3.1 7.5 7.1 7.9l-.1.2z"/></svg> </span> <span class="git-revision-date-localized-plugin git-revision-date-localized-plugin-date" title="October 2, 2026 09:32:15 UTC">October 2, 2026</span> </span> </aside> </article> </div> <script>var tabs=__md_get("__tabs");if(Array.isArray(tabs))e:for(var set of document.querySelectorAll(".tabbed-set")){var labels=set.querySelector(".tabbed-labels");for(var tab of tabs)for(var label of labels.getElementsByTagName("label"))if(label.innerText.trim()===tab){var input=document.getElementById(label.htmlFor);input.checked=!0;continue e}}</script> <script>var target=document.getElementById(location.hash.slice(1));target&&target.name&&(target.checked=target.name.startsWith("__tabbed_"))</script> </div> <button type=button class="md-top md-icon" data-md-component=top hidden> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M13 20h-2V8l-5.5 5.5-1.42-1.42L12 4.16l7.92 7.92-1.42 1.42L13 8z"/></svg> Back to top </button> </main> <footer class=md-footer> <div class="md-footer-meta md-typeset"> <div class="md-footer-meta__inner md-grid"> <div class=md-copyright> <div class=md-copyright__highlight> Copyright &copy; 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+10 -1
View File
@@ -6,6 +6,10 @@ void pop_front();
Remove the first reference token.
## Exception safety
Strong exception safety: if an exception occurs, the original value stays intact.
## Exceptions
Throws [out_of_range.405](https://json.nlohmann.me/home/exceptions/#jsonexceptionout_of_range405) if the JSON pointer has no parent.
@@ -53,6 +57,11 @@ Output:
""
```
## See also
- [front](https://json.nlohmann.me/api/json_pointer/front/index.md) return first reference token
- [push_front](https://json.nlohmann.me/api/json_pointer/push_front/index.md) append an unescaped token at the start of the pointer
## Version history
- Added in version 3.13.0.
- Added in version 3.13.0 unreleased.
+11
View File
@@ -13,6 +13,10 @@ Append an unescaped token at the end of the reference pointer.
`token` (in)
: token to add
## Exception safety
Strong exception safety: if an exception occurs, the original value stays intact.
## Complexity
Amortized constant.
@@ -33,6 +37,13 @@ Amortized constant.
--8<-- "examples/json_pointer__push_back.output"
```
## See also
- [back](back.md) return last reference token
- [pop_back](pop_back.md) remove the last reference token
- [operator/=](operator_slasheq.md) append to the end of the JSON pointer
- [operator/](operator_slash.md) create JSON Pointer by appending
## Version history
- Added in version 3.6.0.
+3 -3
View File
@@ -1,7 +1,7 @@
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<span class=kt>void</span><span class=w> </span><span class=nf>push_back</span><span class=p>(</span><span class=n>string_t</span><span class=o>&amp;&amp;</span><span class=w> </span><span class=n>token</span><span class=p>);</span>
</code></pre></div> <p>Append an unescaped token at the end of the reference pointer.</p> <h2 id=parameters>Parameters<a class=headerlink href=#parameters title="Permanent link">&para;</a></h2> <dl> <dt><code>token</code> (in)</dt> <dd>token to add</dd> </dl> <h2 id=complexity>Complexity<a class=headerlink href=#complexity title="Permanent link">&para;</a></h2> <p>Amortized constant.</p> <h2 id=examples>Examples<a class=headerlink href=#examples title="Permanent link">&para;</a></h2> <details class=example> <summary>Example</summary> <p>The example shows the result of <code>push_back</code> for different <abbr title="JavaScript Object Notation">JSON</abbr> Pointers.</p> <div class=highlight><pre><span></span><code><span class=cp>#include</span><span class=w> </span><span class=cpf>&lt;iostream&gt;</span>
</code></pre></div> <p>Append an unescaped token at the end of the reference pointer.</p> <h2 id=parameters>Parameters<a class=headerlink href=#parameters title="Permanent link">&para;</a></h2> <dl> <dt><code>token</code> (in)</dt> <dd>token to add</dd> </dl> <h2 id=exception-safety>Exception safety<a class=headerlink href=#exception-safety title="Permanent link">&para;</a></h2> <p>Strong exception safety: if an exception occurs, the original value stays intact.</p> <h2 id=complexity>Complexity<a class=headerlink href=#complexity title="Permanent link">&para;</a></h2> <p>Amortized constant.</p> <h2 id=examples>Examples<a class=headerlink href=#examples title="Permanent link">&para;</a></h2> <details class=example> <summary>Example</summary> <p>The example shows the result of <code>push_back</code> for different <abbr title="JavaScript Object Notation">JSON</abbr> Pointers.</p> <div class=highlight><pre><span></span><code><span class=cp>#include</span><span class=w> </span><span class=cpf>&lt;iostream&gt;</span>
<span class=cp>#include</span><span class=w> </span><span class=cpf>&lt;nlohmann/json.hpp&gt;</span>
<span class=k>using</span><span class=w> </span><span class=n>json</span><span class=w> </span><span class=o>=</span><span class=w> </span><span class=n>nlohmann</span><span class=o>::</span><span class=n>json</span><span class=p>;</span>
@@ -26,4 +26,4 @@
<span class=s2>"/foo"</span>
<span class=s2>"/foo/0"</span>
<span class=s2>"/foo/0/bar"</span>
</code></pre></div> </details> <h2 id=version-history>Version history<a class=headerlink href=#version-history title="Permanent link">&para;</a></h2> <ul> <li>Added in version 3.6.0.</li> <li>Changed type of <code>token</code> to <code>string_t</code> in version 3.11.0.</li> </ul> <!-- https://squidfunk.github.io/mkdocs-material/reference/tooltips/#adding-a-glossary --> <aside class=md-source-file> <span class=md-source-file__fact> <span class=md-icon title="Last update"> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M21 13.1c-.1 0-.3.1-.4.2l-1 1 2.1 2.1 1-1c.2-.2.2-.6 0-.8l-1.3-1.3c-.1-.1-.2-.2-.4-.2m-1.9 1.8-6.1 6V23h2.1l6.1-6.1zM12.5 7v5.2l4 2.4-1 1L11 13V7zM11 21.9c-5.1-.5-9-4.8-9-9.9C2 6.5 6.5 2 12 2c5.3 0 9.6 4.1 10 9.3-.3-.1-.6-.2-1-.2s-.7.1-1 .2C19.6 7.2 16.2 4 12 4c-4.4 0-8 3.6-8 8 0 4.1 3.1 7.5 7.1 7.9l-.1.2z"/></svg> </span> <span class="git-revision-date-localized-plugin git-revision-date-localized-plugin-date" title="October 2, 2026 09:23:55 UTC">October 2, 2026</span> </span> </aside> </article> </div> <script>var tabs=__md_get("__tabs");if(Array.isArray(tabs))e:for(var set of document.querySelectorAll(".tabbed-set")){var labels=set.querySelector(".tabbed-labels");for(var tab of tabs)for(var label of labels.getElementsByTagName("label"))if(label.innerText.trim()===tab){var input=document.getElementById(label.htmlFor);input.checked=!0;continue e}}</script> <script>var target=document.getElementById(location.hash.slice(1));target&&target.name&&(target.checked=target.name.startsWith("__tabbed_"))</script> </div> <button type=button class="md-top md-icon" data-md-component=top hidden> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M13 20h-2V8l-5.5 5.5-1.42-1.42L12 4.16l7.92 7.92-1.42 1.42L13 8z"/></svg> Back to top </button> </main> <footer class=md-footer> <div class="md-footer-meta md-typeset"> <div class="md-footer-meta__inner md-grid"> <div class=md-copyright> <div class=md-copyright__highlight> Copyright &copy; 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</code></pre></div> </details> <h2 id=see-also>See also<a class=headerlink href=#see-also title="Permanent link">&para;</a></h2> <ul> <li><a href=../back/ >back</a> return last reference token</li> <li><a href=../pop_back/ >pop_back</a> remove the last reference token</li> <li><a href=../operator_slasheq/ >operator/=</a> append to the end of the <abbr title="JavaScript Object Notation">JSON</abbr> pointer</li> <li><a href=../operator_slash/ >operator/</a> create <abbr title="JavaScript Object Notation">JSON</abbr> Pointer by appending</li> </ul> <h2 id=version-history>Version history<a class=headerlink href=#version-history title="Permanent link">&para;</a></h2> <ul> <li>Added in version 3.6.0.</li> <li>Changed type of <code>token</code> to <code>string_t</code> in version 3.11.0.</li> </ul> <!-- https://squidfunk.github.io/mkdocs-material/reference/tooltips/#adding-a-glossary --> <aside class=md-source-file> <span class=md-source-file__fact> <span class=md-icon title="Last update"> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M21 13.1c-.1 0-.3.1-.4.2l-1 1 2.1 2.1 1-1c.2-.2.2-.6 0-.8l-1.3-1.3c-.1-.1-.2-.2-.4-.2m-1.9 1.8-6.1 6V23h2.1l6.1-6.1zM12.5 7v5.2l4 2.4-1 1L11 13V7zM11 21.9c-5.1-.5-9-4.8-9-9.9C2 6.5 6.5 2 12 2c5.3 0 9.6 4.1 10 9.3-.3-.1-.6-.2-1-.2s-.7.1-1 .2C19.6 7.2 16.2 4 12 4c-4.4 0-8 3.6-8 8 0 4.1 3.1 7.5 7.1 7.9l-.1.2z"/></svg> </span> <span class="git-revision-date-localized-plugin git-revision-date-localized-plugin-date" title="October 2, 2026 09:32:15 UTC">October 2, 2026</span> </span> </aside> </article> </div> <script>var tabs=__md_get("__tabs");if(Array.isArray(tabs))e:for(var set of document.querySelectorAll(".tabbed-set")){var labels=set.querySelector(".tabbed-labels");for(var tab of tabs)for(var label of labels.getElementsByTagName("label"))if(label.innerText.trim()===tab){var input=document.getElementById(label.htmlFor);input.checked=!0;continue e}}</script> <script>var target=document.getElementById(location.hash.slice(1));target&&target.name&&(target.checked=target.name.startsWith("__tabbed_"))</script> </div> <button type=button class="md-top md-icon" data-md-component=top hidden> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M13 20h-2V8l-5.5 5.5-1.42-1.42L12 4.16l7.92 7.92-1.42 1.42L13 8z"/></svg> Back to top </button> </main> <footer class=md-footer> <div class="md-footer-meta md-typeset"> <div class="md-footer-meta__inner md-grid"> <div class=md-copyright> <div class=md-copyright__highlight> Copyright &copy; 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+11
View File
@@ -12,6 +12,10 @@ Append an unescaped token at the end of the reference pointer.
`token` (in) : token to add
## Exception safety
Strong exception safety: if an exception occurs, the original value stays intact.
## Complexity
Amortized constant.
@@ -55,6 +59,13 @@ Output:
"/foo/0/bar"
```
## See also
- [back](https://json.nlohmann.me/api/json_pointer/back/index.md) return last reference token
- [pop_back](https://json.nlohmann.me/api/json_pointer/pop_back/index.md) remove the last reference token
- [operator/=](https://json.nlohmann.me/api/json_pointer/operator_slasheq/index.md) append to the end of the JSON pointer
- [operator/](https://json.nlohmann.me/api/json_pointer/operator_slash/index.md) create JSON Pointer by appending
## Version history
- Added in version 3.6.0.
+10
View File
@@ -13,6 +13,11 @@ Append an unescaped token at the start of the reference pointer.
`token` (in)
: token to add
## Exception safety
Basic guarantee: if an exception is thrown (for instance, if copying the reference token fails), the JSON pointer is
left in a valid state, but its reference tokens may have changed.
## Complexity
Linear in the number of reference tokens in the `json_pointer`.
@@ -33,6 +38,11 @@ Linear in the number of reference tokens in the `json_pointer`.
--8<-- "examples/json_pointer__push_front.output"
```
## See also
- [front](front.md) return first reference token
- [pop_front](pop_front.md) remove the first reference token
## Version history
- Added in version 3.13.0.
+3 -3
View File
@@ -1,7 +1,7 @@
<!doctype html><html lang=en class=no-js> <head><meta charset=utf-8><meta name=viewport content="width=device-width,initial-scale=1"><meta name=author content="Niels Lohmann"><link href="https://json.nlohmann.me/api/json_pointer/push_front/" rel="canonical"><link href=../push_back/ rel=prev><link href=../string_t/ rel=next><link rel=icon href=../../../assets/images/favicon.png><meta name=generator content="mkdocs-1.6.1, mkdocs-material-9.7.7"><title>push_front - JSON for Modern C++</title><link rel=stylesheet href=../../../assets/stylesheets/main.ec1eaa64.min.css><link rel=stylesheet href=../../../assets/stylesheets/palette.ab4e12ef.min.css><link rel="stylesheet" href="../../../assets/external/fonts.googleapis.com/css.61a430c9.css"><style>:root{--md-text-font:"Roboto";--md-code-font:"JetBrains Mono"}</style><link rel=stylesheet href=../../../css/custom.css><script>__md_scope=new 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<!doctype html><html lang=en class=no-js> <head><meta charset=utf-8><meta name=viewport content="width=device-width,initial-scale=1"><meta name=author content="Niels Lohmann"><link href="https://json.nlohmann.me/api/json_pointer/push_front/" rel="canonical"><link href=../push_back/ rel=prev><link href=../string_t/ rel=next><link rel=icon href=../../../assets/images/favicon.png><meta name=generator content="mkdocs-1.6.1, mkdocs-material-9.7.7"><title>push_front - JSON for Modern C++</title><link rel=stylesheet href=../../../assets/stylesheets/main.ec1eaa64.min.css><link rel=stylesheet href=../../../assets/stylesheets/palette.ab4e12ef.min.css><link rel="stylesheet" href="../../../assets/external/fonts.googleapis.com/css.61a430c9.css"><style>:root{--md-text-font:"Roboto";--md-code-font:"JetBrains Mono"}</style><link rel=stylesheet href=../../../css/custom.css><script>__md_scope=new 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data-md-component=logo> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M12 8a3 3 0 0 0 3-3 3 3 0 0 0-3-3 3 3 0 0 0-3 3 3 3 0 0 0 3 3m0 3.54C9.64 9.35 6.5 8 3 8v11c3.5 0 6.64 1.35 9 3.54 2.36-2.19 5.5-3.54 9-3.54V8c-3.5 0-6.64 1.35-9 3.54"/></svg> </a> <label class="md-header__button md-icon" for=__drawer> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M3 6h18v2H3zm0 5h18v2H3zm0 5h18v2H3z"/></svg> </label> <div class=md-header__title data-md-component=header-title> <div class=md-header__ellipsis> <div class=md-header__topic> <span class=md-ellipsis> JSON for Modern C++ </span> </div> <div class=md-header__topic data-md-component=header-topic> <span class=md-ellipsis> push_front </span> </div> </div> </div> <form class=md-header__option data-md-component=palette> <input class=md-option data-md-color-media="(prefers-color-scheme: light)" data-md-color-scheme=default data-md-color-primary=indigo data-md-color-accent=indigo aria-label="Switch to dark 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<span class=kt>void</span><span class=w> </span><span class=nf>push_front</span><span class=p>(</span><span class=n>string_t</span><span class=o>&amp;&amp;</span><span class=w> </span><span class=n>token</span><span class=p>);</span>
</code></pre></div> <p>Append an unescaped token at the start of the reference pointer.</p> <h2 id=parameters>Parameters<a class=headerlink href=#parameters title="Permanent link">&para;</a></h2> <dl> <dt><code>token</code> (in)</dt> <dd>token to add</dd> </dl> <h2 id=complexity>Complexity<a class=headerlink href=#complexity title="Permanent link">&para;</a></h2> <p>Linear in the number of reference tokens in the <code>json_pointer</code>.</p> <h2 id=examples>Examples<a class=headerlink href=#examples title="Permanent link">&para;</a></h2> <details class=example> <summary>Example</summary> <p>The example shows the result of <code>push_front</code> for different <abbr title="JavaScript Object Notation">JSON</abbr> Pointers.</p> <div class=highlight><pre><span></span><code><span class=cp>#include</span><span class=w> </span><span class=cpf>&lt;iostream&gt;</span>
</code></pre></div> <p>Append an unescaped token at the start of the reference pointer.</p> <h2 id=parameters>Parameters<a class=headerlink href=#parameters title="Permanent link">&para;</a></h2> <dl> <dt><code>token</code> (in)</dt> <dd>token to add</dd> </dl> <h2 id=exception-safety>Exception safety<a class=headerlink href=#exception-safety title="Permanent link">&para;</a></h2> <p>Basic guarantee: if an exception is thrown (for instance, if copying the reference token fails), the <abbr title="JavaScript Object Notation">JSON</abbr> pointer is left in a valid state, but its reference tokens may have changed.</p> <h2 id=complexity>Complexity<a class=headerlink href=#complexity title="Permanent link">&para;</a></h2> <p>Linear in the number of reference tokens in the <code>json_pointer</code>.</p> <h2 id=examples>Examples<a class=headerlink href=#examples title="Permanent link">&para;</a></h2> <details class=example> <summary>Example</summary> <p>The example shows the result of <code>push_front</code> for different <abbr title="JavaScript Object Notation">JSON</abbr> Pointers.</p> <div class=highlight><pre><span></span><code><span class=cp>#include</span><span class=w> </span><span class=cpf>&lt;iostream&gt;</span>
<span class=cp>#include</span><span class=w> </span><span class=cpf>&lt;nlohmann/json.hpp&gt;</span>
<span class=k>using</span><span class=w> </span><span class=n>json</span><span class=w> </span><span class=o>=</span><span class=w> </span><span class=n>nlohmann</span><span class=o>::</span><span class=n>json</span><span class=p>;</span>
@@ -26,4 +26,4 @@
<span class=s2>"/foo"</span>
<span class=s2>"/0/foo"</span>
<span class=s2>"/bar/0/foo"</span>
</code></pre></div> </details> <h2 id=version-history>Version history<a class=headerlink href=#version-history title="Permanent link">&para;</a></h2> <ul> <li>Added in version 3.13.0.</li> </ul> <!-- https://squidfunk.github.io/mkdocs-material/reference/tooltips/#adding-a-glossary --> <aside class=md-source-file> <span class=md-source-file__fact> <span class=md-icon title="Last update"> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M21 13.1c-.1 0-.3.1-.4.2l-1 1 2.1 2.1 1-1c.2-.2.2-.6 0-.8l-1.3-1.3c-.1-.1-.2-.2-.4-.2m-1.9 1.8-6.1 6V23h2.1l6.1-6.1zM12.5 7v5.2l4 2.4-1 1L11 13V7zM11 21.9c-5.1-.5-9-4.8-9-9.9C2 6.5 6.5 2 12 2c5.3 0 9.6 4.1 10 9.3-.3-.1-.6-.2-1-.2s-.7.1-1 .2C19.6 7.2 16.2 4 12 4c-4.4 0-8 3.6-8 8 0 4.1 3.1 7.5 7.1 7.9l-.1.2z"/></svg> </span> <span class="git-revision-date-localized-plugin git-revision-date-localized-plugin-date" title="October 2, 2026 09:23:55 UTC">October 2, 2026</span> </span> </aside> </article> </div> <script>var tabs=__md_get("__tabs");if(Array.isArray(tabs))e:for(var set of document.querySelectorAll(".tabbed-set")){var labels=set.querySelector(".tabbed-labels");for(var tab of tabs)for(var label of labels.getElementsByTagName("label"))if(label.innerText.trim()===tab){var input=document.getElementById(label.htmlFor);input.checked=!0;continue e}}</script> <script>var target=document.getElementById(location.hash.slice(1));target&&target.name&&(target.checked=target.name.startsWith("__tabbed_"))</script> </div> <button type=button class="md-top md-icon" data-md-component=top hidden> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M13 20h-2V8l-5.5 5.5-1.42-1.42L12 4.16l7.92 7.92-1.42 1.42L13 8z"/></svg> Back to top </button> </main> <footer class=md-footer> <div class="md-footer-meta md-typeset"> <div class="md-footer-meta__inner md-grid"> <div class=md-copyright> <div class=md-copyright__highlight> Copyright &copy; 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</code></pre></div> </details> <h2 id=see-also>See also<a class=headerlink href=#see-also title="Permanent link">&para;</a></h2> <ul> <li><a href=../front/ >front</a> return first reference token</li> <li><a href=../pop_front/ >pop_front</a> remove the first reference token</li> </ul> <h2 id=version-history>Version history<a class=headerlink href=#version-history title="Permanent link">&para;</a></h2> <ul> <li>Added in version 3.13.0 <span class=unreleased-version title="Not part of a release yet; the latest release is 3.12.0.">unreleased</span>.</li> </ul> <!-- https://squidfunk.github.io/mkdocs-material/reference/tooltips/#adding-a-glossary --> <aside class=md-source-file> <span class=md-source-file__fact> <span class=md-icon title="Last update"> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M21 13.1c-.1 0-.3.1-.4.2l-1 1 2.1 2.1 1-1c.2-.2.2-.6 0-.8l-1.3-1.3c-.1-.1-.2-.2-.4-.2m-1.9 1.8-6.1 6V23h2.1l6.1-6.1zM12.5 7v5.2l4 2.4-1 1L11 13V7zM11 21.9c-5.1-.5-9-4.8-9-9.9C2 6.5 6.5 2 12 2c5.3 0 9.6 4.1 10 9.3-.3-.1-.6-.2-1-.2s-.7.1-1 .2C19.6 7.2 16.2 4 12 4c-4.4 0-8 3.6-8 8 0 4.1 3.1 7.5 7.1 7.9l-.1.2z"/></svg> </span> <span class="git-revision-date-localized-plugin git-revision-date-localized-plugin-date" title="October 2, 2026 09:32:15 UTC">October 2, 2026</span> </span> </aside> </article> </div> <script>var tabs=__md_get("__tabs");if(Array.isArray(tabs))e:for(var set of document.querySelectorAll(".tabbed-set")){var labels=set.querySelector(".tabbed-labels");for(var tab of tabs)for(var label of labels.getElementsByTagName("label"))if(label.innerText.trim()===tab){var input=document.getElementById(label.htmlFor);input.checked=!0;continue e}}</script> <script>var target=document.getElementById(location.hash.slice(1));target&&target.name&&(target.checked=target.name.startsWith("__tabbed_"))</script> </div> <button type=button class="md-top md-icon" data-md-component=top hidden> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M13 20h-2V8l-5.5 5.5-1.42-1.42L12 4.16l7.92 7.92-1.42 1.42L13 8z"/></svg> Back to top </button> </main> <footer class=md-footer> <div class="md-footer-meta md-typeset"> <div class="md-footer-meta__inner md-grid"> <div class=md-copyright> <div class=md-copyright__highlight> Copyright &copy; 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+10 -1
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@@ -12,6 +12,10 @@ Append an unescaped token at the start of the reference pointer.
`token` (in) : token to add
## Exception safety
Basic guarantee: if an exception is thrown (for instance, if copying the reference token fails), the JSON pointer is left in a valid state, but its reference tokens may have changed.
## Complexity
Linear in the number of reference tokens in the `json_pointer`.
@@ -55,6 +59,11 @@ Output:
"/bar/0/foo"
```
## See also
- [front](https://json.nlohmann.me/api/json_pointer/front/index.md) return first reference token
- [pop_front](https://json.nlohmann.me/api/json_pointer/pop_front/index.md) remove the first reference token
## Version history
- Added in version 3.13.0.
- Added in version 3.13.0 unreleased.
+5
View File
@@ -23,6 +23,11 @@ See [`basic_json::string_t`](../basic_json/string_t.md) for more information.
--8<-- "examples/json_pointer__string_t.output"
```
## See also
- [basic_json::string_t](../basic_json/string_t.md) type used to store JSON strings
- [to_string](to_string.md) return a string representation of the JSON pointer
## Version history
- Added in version 3.11.0.
+2 -2
View File
@@ -1,4 +1,4 @@
<!doctype html><html lang=en class=no-js> <head><meta charset=utf-8><meta name=viewport content="width=device-width,initial-scale=1"><meta name=author content="Niels Lohmann"><link href="https://json.nlohmann.me/api/json_pointer/string_t/" rel="canonical"><link href=../push_front/ rel=prev><link href=../to_string/ rel=next><link rel=icon href=../../../assets/images/favicon.png><meta name=generator content="mkdocs-1.6.1, mkdocs-material-9.7.7"><title>string_t - JSON for Modern C++</title><link rel=stylesheet href=../../../assets/stylesheets/main.ec1eaa64.min.css><link rel=stylesheet href=../../../assets/stylesheets/palette.ab4e12ef.min.css><link rel="stylesheet" href="../../../assets/external/fonts.googleapis.com/css.61a430c9.css"><style>:root{--md-text-font:"Roboto";--md-code-font:"JetBrains Mono"}</style><link rel=stylesheet href=../../../css/custom.css><script>__md_scope=new 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</code></pre></div> <p>The string type used for the reference tokens making up the <abbr title="JavaScript Object Notation">JSON</abbr> pointer.</p> <p>See <a href=../../basic_json/string_t/ ><code>basic_json::string_t</code></a> for more information.</p> <h2 id=examples>Examples<a class=headerlink href=#examples title="Permanent link">&para;</a></h2> <details class=example> <summary>Example</summary> <p>The example shows the type <code>string_t</code> and its relation to <code>basic_json::string_t</code>.</p> <div class=highlight><pre><span></span><code><span class=cp>#include</span><span class=w> </span><span class=cpf>&lt;iostream&gt;</span>
<span class=cp>#include</span><span class=w> </span><span class=cpf>&lt;nlohmann/json.hpp&gt;</span>
@@ -14,4 +14,4 @@
<span class=p>}</span>
</code></pre></div> <p>Output:</p> <div class=highlight><pre><span></span><code><span class=err>This</span><span class=w> </span><span class=err>is</span><span class=w> </span><span class=err>a</span><span class=w> </span><span class=err>s</span><span class=kc>tr</span><span class=err>i</span><span class=kc>n</span><span class=err>g.</span>
<span class=kc>true</span>
</code></pre></div> </details> <h2 id=version-history>Version history<a class=headerlink href=#version-history title="Permanent link">&para;</a></h2> <ul> <li>Added in version 3.11.0.</li> </ul> <!-- https://squidfunk.github.io/mkdocs-material/reference/tooltips/#adding-a-glossary --> <aside class=md-source-file> <span class=md-source-file__fact> <span class=md-icon title="Last update"> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M21 13.1c-.1 0-.3.1-.4.2l-1 1 2.1 2.1 1-1c.2-.2.2-.6 0-.8l-1.3-1.3c-.1-.1-.2-.2-.4-.2m-1.9 1.8-6.1 6V23h2.1l6.1-6.1zM12.5 7v5.2l4 2.4-1 1L11 13V7zM11 21.9c-5.1-.5-9-4.8-9-9.9C2 6.5 6.5 2 12 2c5.3 0 9.6 4.1 10 9.3-.3-.1-.6-.2-1-.2s-.7.1-1 .2C19.6 7.2 16.2 4 12 4c-4.4 0-8 3.6-8 8 0 4.1 3.1 7.5 7.1 7.9l-.1.2z"/></svg> </span> <span class="git-revision-date-localized-plugin git-revision-date-localized-plugin-date" title="October 2, 2026 09:23:55 UTC">October 2, 2026</span> </span> </aside> </article> </div> <script>var tabs=__md_get("__tabs");if(Array.isArray(tabs))e:for(var set of document.querySelectorAll(".tabbed-set")){var labels=set.querySelector(".tabbed-labels");for(var tab of tabs)for(var label of labels.getElementsByTagName("label"))if(label.innerText.trim()===tab){var input=document.getElementById(label.htmlFor);input.checked=!0;continue e}}</script> <script>var target=document.getElementById(location.hash.slice(1));target&&target.name&&(target.checked=target.name.startsWith("__tabbed_"))</script> </div> <button type=button class="md-top md-icon" data-md-component=top hidden> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M13 20h-2V8l-5.5 5.5-1.42-1.42L12 4.16l7.92 7.92-1.42 1.42L13 8z"/></svg> Back to top </button> </main> <footer class=md-footer> <div class="md-footer-meta md-typeset"> <div class="md-footer-meta__inner md-grid"> <div class=md-copyright> <div class=md-copyright__highlight> Copyright &copy; 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</code></pre></div> </details> <h2 id=see-also>See also<a class=headerlink href=#see-also title="Permanent link">&para;</a></h2> <ul> <li><a href=../../basic_json/string_t/ >basic_json::string_t</a> type used to store <abbr title="JavaScript Object Notation">JSON</abbr> strings</li> <li><a href=../to_string/ >to_string</a> return a string representation of the <abbr title="JavaScript Object Notation">JSON</abbr> pointer</li> </ul> <h2 id=version-history>Version history<a class=headerlink href=#version-history title="Permanent link">&para;</a></h2> <ul> <li>Added in version 3.11.0.</li> </ul> <!-- https://squidfunk.github.io/mkdocs-material/reference/tooltips/#adding-a-glossary --> <aside class=md-source-file> <span class=md-source-file__fact> <span class=md-icon title="Last update"> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M21 13.1c-.1 0-.3.1-.4.2l-1 1 2.1 2.1 1-1c.2-.2.2-.6 0-.8l-1.3-1.3c-.1-.1-.2-.2-.4-.2m-1.9 1.8-6.1 6V23h2.1l6.1-6.1zM12.5 7v5.2l4 2.4-1 1L11 13V7zM11 21.9c-5.1-.5-9-4.8-9-9.9C2 6.5 6.5 2 12 2c5.3 0 9.6 4.1 10 9.3-.3-.1-.6-.2-1-.2s-.7.1-1 .2C19.6 7.2 16.2 4 12 4c-4.4 0-8 3.6-8 8 0 4.1 3.1 7.5 7.1 7.9l-.1.2z"/></svg> </span> <span class="git-revision-date-localized-plugin git-revision-date-localized-plugin-date" title="October 2, 2026 09:32:15 UTC">October 2, 2026</span> </span> </aside> </article> </div> <script>var tabs=__md_get("__tabs");if(Array.isArray(tabs))e:for(var set of document.querySelectorAll(".tabbed-set")){var labels=set.querySelector(".tabbed-labels");for(var tab of tabs)for(var label of labels.getElementsByTagName("label"))if(label.innerText.trim()===tab){var input=document.getElementById(label.htmlFor);input.checked=!0;continue e}}</script> <script>var target=document.getElementById(location.hash.slice(1));target&&target.name&&(target.checked=target.name.startsWith("__tabbed_"))</script> </div> <button type=button class="md-top md-icon" data-md-component=top hidden> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M13 20h-2V8l-5.5 5.5-1.42-1.42L12 4.16l7.92 7.92-1.42 1.42L13 8z"/></svg> Back to top </button> </main> <footer class=md-footer> <div class="md-footer-meta md-typeset"> <div class="md-footer-meta__inner md-grid"> <div class=md-copyright> <div class=md-copyright__highlight> Copyright &copy; 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+5
View File
@@ -37,6 +37,11 @@ This is a string.
true
```
## See also
- [basic_json::string_t](https://json.nlohmann.me/api/basic_json/string_t/index.md) type used to store JSON strings
- [to_string](https://json.nlohmann.me/api/json_pointer/to_string/index.md) return a string representation of the JSON pointer
## Version history
- Added in version 3.11.0.
+13
View File
@@ -10,6 +10,14 @@ Return a string representation of the JSON pointer.
A string representation of the JSON pointer
## Exception safety
Strong exception safety: if an exception occurs, the original value stays intact.
## Complexity
Linear in the total length of the reference tokens.
## Notes
For each JSON pointer `ptr`, it holds:
@@ -34,6 +42,11 @@ ptr == json_pointer(ptr.to_string());
--8<-- "examples/json_pointer__to_string.output"
```
## See also
- [operator string_t](operator_string_t.md) return a string representation of the JSON pointer (deprecated)
- [operator<<](../operator_ltlt.md) write a JSON pointer to a stream
## Version history
- Since version 2.0.0.
+3 -3
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@@ -1,5 +1,5 @@
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</code></pre></div> <p>Return a string representation of the <abbr title="JavaScript Object Notation">JSON</abbr> pointer.</p> <h2 id=return-value>Return value<a class=headerlink href=#return-value title="Permanent link">&para;</a></h2> <p>A string representation of the <abbr title="JavaScript Object Notation">JSON</abbr> pointer</p> <h2 id=notes>Notes<a class=headerlink href=#notes title="Permanent link">&para;</a></h2> <p>For each <abbr title="JavaScript Object Notation">JSON</abbr> pointer <code>ptr</code>, it holds:</p> <div class=highlight><pre><span></span><code><span class=n>ptr</span><span class=w> </span><span class=o>==</span><span class=w> </span><span class=n>json_pointer</span><span class=p>(</span><span class=n>ptr</span><span class=p>.</span><span class=n>to_string</span><span class=p>());</span>
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data-md-component=logo> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M12 8a3 3 0 0 0 3-3 3 3 0 0 0-3-3 3 3 0 0 0-3 3 3 3 0 0 0 3 3m0 3.54C9.64 9.35 6.5 8 3 8v11c3.5 0 6.64 1.35 9 3.54 2.36-2.19 5.5-3.54 9-3.54V8c-3.5 0-6.64 1.35-9 3.54"/></svg> </a> <label class="md-header__button md-icon" for=__drawer> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M3 6h18v2H3zm0 5h18v2H3zm0 5h18v2H3z"/></svg> </label> <div class=md-header__title data-md-component=header-title> <div class=md-header__ellipsis> <div class=md-header__topic> <span class=md-ellipsis> JSON for Modern C++ </span> </div> <div class=md-header__topic data-md-component=header-topic> <span class=md-ellipsis> to_string </span> </div> </div> </div> <form class=md-header__option data-md-component=palette> <input class=md-option data-md-color-media="(prefers-color-scheme: light)" data-md-color-scheme=default data-md-color-primary=indigo data-md-color-accent=indigo aria-label="Switch to dark 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</code></pre></div> <p>Return a string representation of the <abbr title="JavaScript Object Notation">JSON</abbr> pointer.</p> <h2 id=return-value>Return value<a class=headerlink href=#return-value title="Permanent link">&para;</a></h2> <p>A string representation of the <abbr title="JavaScript Object Notation">JSON</abbr> pointer</p> <h2 id=exception-safety>Exception safety<a class=headerlink href=#exception-safety title="Permanent link">&para;</a></h2> <p>Strong exception safety: if an exception occurs, the original value stays intact.</p> <h2 id=complexity>Complexity<a class=headerlink href=#complexity title="Permanent link">&para;</a></h2> <p>Linear in the total length of the reference tokens.</p> <h2 id=notes>Notes<a class=headerlink href=#notes title="Permanent link">&para;</a></h2> <p>For each <abbr title="JavaScript Object Notation">JSON</abbr> pointer <code>ptr</code>, it holds:</p> <div class=highlight><pre><span></span><code><span class=n>ptr</span><span class=w> </span><span class=o>==</span><span class=w> </span><span class=n>json_pointer</span><span class=p>(</span><span class=n>ptr</span><span class=p>.</span><span class=n>to_string</span><span class=p>());</span>
</code></pre></div> <h2 id=examples>Examples<a class=headerlink href=#examples title="Permanent link">&para;</a></h2> <details class=example> <summary>Example</summary> <p>The example shows the result of <code>to_string</code>.</p> <div class=highlight><pre><span></span><code><span class=cp>#include</span><span class=w> </span><span class=cpf>&lt;iostream&gt;</span>
<span class=cp>#include</span><span class=w> </span><span class=cpf>&lt;nlohmann/json.hpp&gt;</span>
@@ -46,4 +46,4 @@
<span class=s2>"/k"</span><span class=err>l</span><span class=s2>"</span>
<span class=s2>"</span><span class=err>/</span><span class=w> </span><span class=s2>"</span>
<span class=s2>"</span><span class=err>/m~</span><span class=mi>0</span><span class=kc>n</span><span class=err>"</span>
</code></pre></div> </details> <h2 id=version-history>Version history<a class=headerlink href=#version-history title="Permanent link">&para;</a></h2> <ul> <li>Since version 2.0.0.</li> <li>Changed return type to <code>string_t</code> in version 3.11.0.</li> </ul> <!-- https://squidfunk.github.io/mkdocs-material/reference/tooltips/#adding-a-glossary --> <aside class=md-source-file> <span class=md-source-file__fact> <span class=md-icon title="Last update"> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M21 13.1c-.1 0-.3.1-.4.2l-1 1 2.1 2.1 1-1c.2-.2.2-.6 0-.8l-1.3-1.3c-.1-.1-.2-.2-.4-.2m-1.9 1.8-6.1 6V23h2.1l6.1-6.1zM12.5 7v5.2l4 2.4-1 1L11 13V7zM11 21.9c-5.1-.5-9-4.8-9-9.9C2 6.5 6.5 2 12 2c5.3 0 9.6 4.1 10 9.3-.3-.1-.6-.2-1-.2s-.7.1-1 .2C19.6 7.2 16.2 4 12 4c-4.4 0-8 3.6-8 8 0 4.1 3.1 7.5 7.1 7.9l-.1.2z"/></svg> </span> <span class="git-revision-date-localized-plugin git-revision-date-localized-plugin-date" title="October 2, 2026 09:23:55 UTC">October 2, 2026</span> </span> </aside> </article> </div> <script>var tabs=__md_get("__tabs");if(Array.isArray(tabs))e:for(var set of document.querySelectorAll(".tabbed-set")){var labels=set.querySelector(".tabbed-labels");for(var tab of tabs)for(var label of labels.getElementsByTagName("label"))if(label.innerText.trim()===tab){var input=document.getElementById(label.htmlFor);input.checked=!0;continue e}}</script> <script>var target=document.getElementById(location.hash.slice(1));target&&target.name&&(target.checked=target.name.startsWith("__tabbed_"))</script> </div> <button type=button class="md-top md-icon" data-md-component=top hidden> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M13 20h-2V8l-5.5 5.5-1.42-1.42L12 4.16l7.92 7.92-1.42 1.42L13 8z"/></svg> Back to top </button> </main> <footer class=md-footer> <div class="md-footer-meta md-typeset"> <div class="md-footer-meta__inner md-grid"> <div class=md-copyright> <div class=md-copyright__highlight> Copyright &copy; 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</code></pre></div> </details> <h2 id=see-also>See also<a class=headerlink href=#see-also title="Permanent link">&para;</a></h2> <ul> <li><a href=../operator_string_t/ >operator string_t</a> return a string representation of the <abbr title="JavaScript Object Notation">JSON</abbr> pointer (deprecated)</li> <li><a href=../../operator_ltlt/ >operator&lt;&lt;</a> write a <abbr title="JavaScript Object Notation">JSON</abbr> pointer to a stream</li> </ul> <h2 id=version-history>Version history<a class=headerlink href=#version-history title="Permanent link">&para;</a></h2> <ul> <li>Since version 2.0.0.</li> <li>Changed return type to <code>string_t</code> in version 3.11.0.</li> </ul> <!-- https://squidfunk.github.io/mkdocs-material/reference/tooltips/#adding-a-glossary --> <aside class=md-source-file> <span class=md-source-file__fact> <span class=md-icon title="Last update"> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M21 13.1c-.1 0-.3.1-.4.2l-1 1 2.1 2.1 1-1c.2-.2.2-.6 0-.8l-1.3-1.3c-.1-.1-.2-.2-.4-.2m-1.9 1.8-6.1 6V23h2.1l6.1-6.1zM12.5 7v5.2l4 2.4-1 1L11 13V7zM11 21.9c-5.1-.5-9-4.8-9-9.9C2 6.5 6.5 2 12 2c5.3 0 9.6 4.1 10 9.3-.3-.1-.6-.2-1-.2s-.7.1-1 .2C19.6 7.2 16.2 4 12 4c-4.4 0-8 3.6-8 8 0 4.1 3.1 7.5 7.1 7.9l-.1.2z"/></svg> </span> <span class="git-revision-date-localized-plugin git-revision-date-localized-plugin-date" title="October 2, 2026 09:32:15 UTC">October 2, 2026</span> </span> </aside> </article> </div> <script>var tabs=__md_get("__tabs");if(Array.isArray(tabs))e:for(var set of document.querySelectorAll(".tabbed-set")){var labels=set.querySelector(".tabbed-labels");for(var tab of tabs)for(var label of labels.getElementsByTagName("label"))if(label.innerText.trim()===tab){var input=document.getElementById(label.htmlFor);input.checked=!0;continue e}}</script> <script>var target=document.getElementById(location.hash.slice(1));target&&target.name&&(target.checked=target.name.startsWith("__tabbed_"))</script> </div> <button type=button class="md-top md-icon" data-md-component=top hidden> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M13 20h-2V8l-5.5 5.5-1.42-1.42L12 4.16l7.92 7.92-1.42 1.42L13 8z"/></svg> Back to top </button> </main> <footer class=md-footer> <div class="md-footer-meta md-typeset"> <div class="md-footer-meta__inner md-grid"> <div class=md-copyright> <div class=md-copyright__highlight> Copyright &copy; 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+13
View File
@@ -10,6 +10,14 @@ Return a string representation of the JSON pointer.
A string representation of the JSON pointer
## Exception safety
Strong exception safety: if an exception occurs, the original value stays intact.
## Complexity
Linear in the total length of the reference tokens.
## Notes
For each JSON pointer `ptr`, it holds:
@@ -78,6 +86,11 @@ Output:
"/m~0n"
```
## See also
- [operator string_t](https://json.nlohmann.me/api/json_pointer/operator_string_t/index.md) return a string representation of the JSON pointer (deprecated)
- [operator\<<](https://json.nlohmann.me/api/operator_ltlt/index.md) write a JSON pointer to a stream
## Version history
- Since version 2.0.0.