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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/features/binary_formats/bon8/" rel="canonical"><link href=../bjdata/ rel=prev><link href=../bson/ rel=next><link rel=icon href=../../../assets/images/favicon.png><meta name=generator content="mkdocs-1.6.1, mkdocs-material-9.7.7"><title>BON8 - 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=#bon8 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> BON8 </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 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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> <div class=md-searchLine truncated
<span class=cp>#include</span><span class=w> </span><span class=cpf>&lt;iomanip&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>using</span><span class=w> </span><span class=k>namespace</span><span class=w> </span><span class=nn>nlohmann</span><span class=o>::</span><span class=nn>literals</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>// create a JSON value</span>
<span class=w> </span><span class=n>json</span><span class=w> </span><span class=n>j</span><span class=w> </span><span class=o>=</span><span class=w> </span><span class=sa>R</span><span class=s>"</span><span class=dl>(</span><span class=s>{"compact": true, "format": "BON8", "schema": 0}</span><span class=dl>)</span><span class=s>"</span><span class=n>_json</span><span class=p>;</span>
<span class=w> </span><span class=c1>// serialize it to BON8</span>
<span class=w> </span><span class=n>std</span><span class=o>::</span><span class=n>vector</span><span class=o>&lt;</span><span class=n>std</span><span class=o>::</span><span class=kt>uint8_t</span><span class=o>&gt;</span><span class=w> </span><span class=n>v</span><span class=w> </span><span class=o>=</span><span class=w> </span><span class=n>json</span><span class=o>::</span><span class=n>to_bon8</span><span class=p>(</span><span class=n>j</span><span class=p>);</span>
<span class=w> </span><span class=c1>// print the vector content</span>
<span class=w> </span><span class=k>for</span><span class=w> </span><span class=p>(</span><span class=k>auto</span><span class=o>&amp;</span><span class=w> </span><span class=kt>byte</span><span class=w> </span><span class=o>:</span><span class=w> </span><span class=n>v</span><span class=p>)</span>
<span class=w> </span><span class=p>{</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>"0x"</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>hex</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>setw</span><span class=p>(</span><span class=mi>2</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>setfill</span><span class=p>(</span><span class=sc>'0'</span><span class=p>)</span><span class=w> </span><span class=o>&lt;&lt;</span><span class=w> </span><span class=p>(</span><span class=kt>int</span><span class=p>)</span><span class=kt>byte</span><span class=w> </span><span class=o>&lt;&lt;</span><span class=w> </span><span class=s>" "</span><span class=p>;</span>
<span class=w> </span><span class=p>}</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=n>std</span><span class=o>::</span><span class=n>endl</span><span class=p>;</span>
<span class=p>}</span>
</code></pre></div> <p>Output:</p> <div class=highlight><pre><span></span><code><span class=mh>0x89</span><span class=w> </span><span class=mh>0x63</span><span class=w> </span><span class=mh>0x6f</span><span class=w> </span><span class=mh>0x6d</span><span class=w> </span><span class=mh>0x70</span><span class=w> </span><span class=mh>0x61</span><span class=w> </span><span class=mh>0x63</span><span class=w> </span><span class=mh>0x74</span><span class=w> </span><span class=mh>0xf9</span><span class=w> </span><span class=mh>0x66</span><span class=w> </span><span class=mh>0x6f</span><span class=w> </span><span class=mh>0x72</span><span class=w> </span><span class=mh>0x6d</span><span class=w> </span><span class=mh>0x61</span><span class=w> </span><span class=mh>0x74</span><span class=w> </span><span class=mh>0xff</span><span class=w> </span><span class=mh>0x42</span><span class=w> </span><span class=mh>0x4f</span><span class=w> </span><span class=mh>0x4e</span><span class=w> </span><span class=mh>0x38</span><span class=w> </span><span class=mh>0xff</span><span class=w> </span><span class=mh>0x73</span><span class=w> </span><span class=mh>0x63</span><span class=w> </span><span class=mh>0x68</span><span class=w> </span><span class=mh>0x65</span><span class=w> </span><span class=mh>0x6d</span><span class=w> </span><span class=mh>0x61</span><span class=w> </span><span class=mh>0x90</span><span class=w> </span>
</code></pre></div> </details> <h2 id=deserialization>Deserialization<a class=headerlink href=#deserialization title="Permanent link">&para;</a></h2> <p>The library maps <abbr title="Binary Object Notation 8">BON8</abbr> types to <abbr title="JavaScript Object Notation">JSON</abbr> value types as follows:</p> <table> <thead> <tr> <th><abbr title="Binary Object Notation 8">BON8</abbr> type</th> <th><abbr title="JavaScript Object Notation">JSON</abbr> value type</th> <th>first byte</th> </tr> </thead> <tbody> <tr> <td><abbr title="Unicode Transformation Format">UTF</abbr>-8 string</td> <td>string</td> <td>0x00..0x7F</td> </tr> <tr> <td>array with count</td> <td>array</td> <td>0x80..0x84</td> </tr> <tr> <td>array (terminated by 0xFE)</td> <td>array</td> <td>0x85</td> </tr> <tr> <td>object with count</td> <td>object</td> <td>0x86..0x8A</td> </tr> <tr> <td>object (terminated by 0xFE)</td> <td>object</td> <td>0x8B</td> </tr> <tr> <td>int32</td> <td>number_unsigned or number_integer</td> <td>0x8C</td> </tr> <tr> <td>int64</td> <td>number_unsigned or number_integer</td> <td>0x8D</td> </tr> <tr> <td>binary32</td> <td>number_float</td> <td>0x8E</td> </tr> <tr> <td>binary64</td> <td>number_float</td> <td>0x8F</td> </tr> <tr> <td>1-byte positive integer</td> <td>number_unsigned</td> <td>0x90..0xB7</td> </tr> <tr> <td>1-byte negative integer</td> <td>number_integer</td> <td>0xB8..0xC1</td> </tr> <tr> <td><abbr title="Unicode Transformation Format">UTF</abbr>-8 string</td> <td>string</td> <td>0xC2..0xF4, followed by 0x80..0xBF</td> </tr> <tr> <td>2- to 4-byte positive integer</td> <td>number_unsigned</td> <td>0xC2..0xF7, followed by 0x00..0x7F</td> </tr> <tr> <td>2- to 4-byte negative integer</td> <td>number_integer</td> <td>0xC2..0xF7, followed by 0xC0..0xFF</td> </tr> <tr> <td>false</td> <td><code>false</code></td> <td>0xF8</td> </tr> <tr> <td>true</td> <td><code>true</code></td> <td>0xF9</td> </tr> <tr> <td>null</td> <td><code>null</code></td> <td>0xFA</td> </tr> <tr> <td>-1.0</td> <td>number_float</td> <td>0xFB</td> </tr> <tr> <td>0.0</td> <td>number_float</td> <td>0xFC</td> </tr> <tr> <td>1.0</td> <td>number_float</td> <td>0xFD</td> </tr> <tr> <td>empty string</td> <td>string</td> <td>0xFF</td> </tr> </tbody> </table> <p>Non-negative integers are read as number_unsigned, negative integers as number_integer.</p> <div class="admonition info"> <p class=admonition-title>Info</p> <p>Values that do not use the canonical representation, such as integers with a longer encoding than necessary, arrays and objects with up to four elements that are terminated by 0xFE, unsorted object keys, or a 0xFF after a string that would also end without it, are accepted. A second 0xFF is not a terminator but an empty string.</p> <p>Strings must be valid <abbr title="Unicode Transformation Format">UTF</abbr>-8, and the last string of a message must be terminated by 0xFF.</p> </div> <div class="admonition info"> <p class=admonition-title>Info</p> <p>Any <abbr title="Binary Object Notation 8">BON8</abbr> output created by <code>to_bon8</code> can be successfully parsed by <code>from_bon8</code>.</p> </div> <details class=example> <summary>Example</summary> <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;iomanip&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=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>// create byte vector</span>
<span class=w> </span><span class=n>std</span><span class=o>::</span><span class=n>vector</span><span class=o>&lt;</span><span class=n>std</span><span class=o>::</span><span class=kt>uint8_t</span><span class=o>&gt;</span><span class=w> </span><span class=n>v</span><span class=w> </span><span class=o>=</span><span class=w> </span><span class=p>{</span><span class=mh>0x89</span><span class=p>,</span><span class=w> </span><span class=mh>0x63</span><span class=p>,</span><span class=w> </span><span class=mh>0x6f</span><span class=p>,</span><span class=w> </span><span class=mh>0x6d</span><span class=p>,</span><span class=w> </span><span class=mh>0x70</span><span class=p>,</span><span class=w> </span><span class=mh>0x61</span><span class=p>,</span><span class=w> </span><span class=mh>0x63</span><span class=p>,</span><span class=w> </span><span class=mh>0x74</span><span class=p>,</span>
<span class=w> </span><span class=mh>0xf9</span><span class=p>,</span><span class=w> </span><span class=mh>0x66</span><span class=p>,</span><span class=w> </span><span class=mh>0x6f</span><span class=p>,</span><span class=w> </span><span class=mh>0x72</span><span class=p>,</span><span class=w> </span><span class=mh>0x6d</span><span class=p>,</span><span class=w> </span><span class=mh>0x61</span><span class=p>,</span><span class=w> </span><span class=mh>0x74</span><span class=p>,</span><span class=w> </span><span class=mh>0xff</span><span class=p>,</span>
<span class=w> </span><span class=mh>0x42</span><span class=p>,</span><span class=w> </span><span class=mh>0x4f</span><span class=p>,</span><span class=w> </span><span class=mh>0x4e</span><span class=p>,</span><span class=w> </span><span class=mh>0x38</span><span class=p>,</span><span class=w> </span><span class=mh>0xff</span><span class=p>,</span><span class=w> </span><span class=mh>0x73</span><span class=p>,</span><span class=w> </span><span class=mh>0x63</span><span class=p>,</span><span class=w> </span><span class=mh>0x68</span><span class=p>,</span>
<span class=w> </span><span class=mh>0x65</span><span class=p>,</span><span class=w> </span><span class=mh>0x6d</span><span class=p>,</span><span class=w> </span><span class=mh>0x61</span><span class=p>,</span><span class=w> </span><span class=mh>0x90</span>
<span class=w> </span><span class=p>};</span>
<span class=w> </span><span class=c1>// deserialize it with BON8</span>
<span class=w> </span><span class=n>json</span><span class=w> </span><span class=n>j</span><span class=w> </span><span class=o>=</span><span class=w> </span><span class=n>json</span><span class=o>::</span><span class=n>from_bon8</span><span class=p>(</span><span class=n>v</span><span class=p>);</span>
<span class=w> </span><span class=c1>// print the deserialized JSON value</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=n>std</span><span class=o>::</span><span class=n>setw</span><span class=p>(</span><span class=mi>2</span><span class=p>)</span><span class=w> </span><span class=o>&lt;&lt;</span><span class=w> </span><span class=n>j</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=p>}</span>
</code></pre></div> <p>Output:</p> <div class=highlight><pre><span></span><code><span class=p>{</span>
<span class=w> </span><span class=nt>"compact"</span><span class=p>:</span><span class=w> </span><span class=kc>true</span><span class=p>,</span>
<span class=w> </span><span class=nt>"format"</span><span class=p>:</span><span class=w> </span><span class=s2>"BON8"</span><span class=p>,</span>
<span class=w> </span><span class=nt>"schema"</span><span class=p>:</span><span class=w> </span><span class=mi>0</span>
<span class=p>}</span>
</code></pre></div> </details> <!-- 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="September 27, 2026 18:40:13 UTC">September 27, 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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# BON8
BON8 (Binary Object Notation 8) is a compact binary serialization format for JSON values. It uses the byte values that cannot begin a UTF-8 character as type markers, so strings are stored as plain UTF-8 without a length prefix: a string ends at the first byte that cannot continue it. Integers from -10 to 39, `true`, `false`, `null`, and the floating-point values -1.0, 0.0, and 1.0 take a single byte, and arrays and objects with up to four elements need no terminator.
References
- [BON8 specification](https://github.com/hikoworks/hikogui/blob/main/docs/BON8.md)
- [Reference implementation](https://github.com/hikoworks/hikogui/blob/main/src/hikogui/codec/BON8.hpp) in HikoGUI
## Serialization
The library uses the following mapping from JSON values types to BON8 types according to the BON8 specification:
| JSON value type | value/range | BON8 type | first byte |
| --------------- | ------------------------------------------ | --------------------------- | ---------------------- |
| null | `null` | null | 0xFA |
| boolean | `true` | true | 0xF9 |
| boolean | `false` | false | 0xF8 |
| number_integer | -9223372036854775808..-2147483649 | int64 | 0x8D |
| number_integer | -2147483648..-33818507 | int32 | 0x8C |
| number_integer | -33818506..-264075 | 4-byte negative integer | 0xF0..0xF7 |
| number_integer | -264074..-1931 | 3-byte negative integer | 0xE0..0xEF |
| number_integer | -1930..-11 | 2-byte negative integer | 0xC2..0xDF |
| number_integer | -10..-1 | 1-byte negative integer | 0xB8..0xC1 |
| number_integer | 0..39 | 1-byte positive integer | 0x90..0xB7 |
| number_integer | 40..3879 | 2-byte positive integer | 0xC2..0xDF |
| number_integer | 3880..528167 | 3-byte positive integer | 0xE0..0xEF |
| number_integer | 528168..67637031 | 4-byte positive integer | 0xF0..0xF7 |
| number_integer | 67637032..2147483647 | int32 | 0x8C |
| number_integer | 2147483648..9223372036854775807 | int64 | 0x8D |
| number_unsigned | 0..39 | 1-byte positive integer | 0x90..0xB7 |
| number_unsigned | 40..3879 | 2-byte positive integer | 0xC2..0xDF |
| number_unsigned | 3880..528167 | 3-byte positive integer | 0xE0..0xEF |
| number_unsigned | 528168..67637031 | 4-byte positive integer | 0xF0..0xF7 |
| number_unsigned | 67637032..2147483647 | int32 | 0x8C |
| number_unsigned | 2147483648..9223372036854775807 | int64 | 0x8D |
| number_float | `-1.0` | -1.0 | 0xFB |
| number_float | `0.0` | 0.0 | 0xFC |
| number_float | `1.0` | 1.0 | 0xFD |
| number_float | *any other value representable by a float* | binary32 | 0x8E |
| number_float | *any value NOT representable by a float* | binary64 | 0x8F |
| string | *empty* | end of string | 0xFF |
| string | *non-empty* | UTF-8 string | 0x00..0x7F, 0xC2..0xF4 |
| array | *size*: 0..4 | array with count | 0x80..0x84 |
| array | *size*: 5 or more | array (terminated by 0xFE) | 0x85 |
| object | *size*: 0..4 | object with count | 0x86..0x8A |
| object | *size*: 5 or more | object (terminated by 0xFE) | 0x8B |
| binary | *size*: 0..4 | array with count | 0x80..0x84 |
| binary | *size*: 5 or more | array (terminated by 0xFE) | 0x85 |
An integer that takes 2 to 4 bytes starts with a UTF-8 lead byte (0xC2..0xF7) that is followed by a byte that cannot continue a UTF-8 character: 0x00..0x7F for positive and 0xC0..0xFF for negative integers. A string is terminated by 0xFF only if it is empty, if another string follows it, or if it is the last value of the message; otherwise, the first byte of the next value ends it.
Complete mapping
Except for the values listed below, any JSON value can be converted to a BON8 value.
Any BON8 output created by `to_bon8` can be successfully parsed by `from_bon8`.
Unsupported values
The following values can **not** be converted to a BON8 value:
- unsigned integers above 9223372036854775807, because BON8 has no unsigned 64-bit integer type ([out_of_range.407](https://json.nlohmann.me/home/exceptions/#jsonexceptionout_of_range407))
- strings that are not valid UTF-8, because the end of a string is determined from its encoding ([type_error.316](https://json.nlohmann.me/home/exceptions/#jsonexceptiontype_error316))
NaN/infinity handling
`-0.0`, `Infinity`, and `-Infinity` are serialized as binary32 (type 0x8E, 5 bytes total). `NaN` is serialized as the binary32 value 0x7F800001 that the specification recommends. This is in contrast to the [dump](https://json.nlohmann.me/api/basic_json/dump/index.md) function which serializes NaN or Infinity to `null`.
Binary values
BON8 has no binary type. Binary values are serialized as arrays of integers (0..255), so they are read back as arrays. The subtype is not serialized.
Canonical representation
The output follows the specification's canonical representation rules: every value uses the shortest encoding, floating-point numbers use binary32 whenever that loses no precision, and object keys are sorted by their UTF-8 code units. There are two exceptions:
- Strings are not normalized to Unicode Normalization Form C (NFC).
- Object keys are written in the order of the object type, which is sorted for `json`, but not for [`ordered_json`](https://json.nlohmann.me/api/ordered_json/index.md).
Example
```
#include <iostream>
#include <iomanip>
#include <nlohmann/json.hpp>
using json = nlohmann::json;
using namespace nlohmann::literals;
int main()
{
// create a JSON value
json j = R"({"compact": true, "format": "BON8", "schema": 0})"_json;
// serialize it to BON8
std::vector<std::uint8_t> v = json::to_bon8(j);
// print the vector content
for (auto& byte : v)
{
std::cout << "0x" << std::hex << std::setw(2) << std::setfill('0') << (int)byte << " ";
}
std::cout << std::endl;
}
```
Output:
```
0x89 0x63 0x6f 0x6d 0x70 0x61 0x63 0x74 0xf9 0x66 0x6f 0x72 0x6d 0x61 0x74 0xff 0x42 0x4f 0x4e 0x38 0xff 0x73 0x63 0x68 0x65 0x6d 0x61 0x90
```
## Deserialization
The library maps BON8 types to JSON value types as follows:
| BON8 type | JSON value type | first byte |
| ----------------------------- | --------------------------------- | ---------------------------------- |
| UTF-8 string | string | 0x00..0x7F |
| array with count | array | 0x80..0x84 |
| array (terminated by 0xFE) | array | 0x85 |
| object with count | object | 0x86..0x8A |
| object (terminated by 0xFE) | object | 0x8B |
| int32 | number_unsigned or number_integer | 0x8C |
| int64 | number_unsigned or number_integer | 0x8D |
| binary32 | number_float | 0x8E |
| binary64 | number_float | 0x8F |
| 1-byte positive integer | number_unsigned | 0x90..0xB7 |
| 1-byte negative integer | number_integer | 0xB8..0xC1 |
| UTF-8 string | string | 0xC2..0xF4, followed by 0x80..0xBF |
| 2- to 4-byte positive integer | number_unsigned | 0xC2..0xF7, followed by 0x00..0x7F |
| 2- to 4-byte negative integer | number_integer | 0xC2..0xF7, followed by 0xC0..0xFF |
| false | `false` | 0xF8 |
| true | `true` | 0xF9 |
| null | `null` | 0xFA |
| -1.0 | number_float | 0xFB |
| 0.0 | number_float | 0xFC |
| 1.0 | number_float | 0xFD |
| empty string | string | 0xFF |
Non-negative integers are read as number_unsigned, negative integers as number_integer.
Info
Values that do not use the canonical representation, such as integers with a longer encoding than necessary, arrays and objects with up to four elements that are terminated by 0xFE, unsorted object keys, or a 0xFF after a string that would also end without it, are accepted. A second 0xFF is not a terminator but an empty string.
Strings must be valid UTF-8, and the last string of a message must be terminated by 0xFF.
Info
Any BON8 output created by `to_bon8` can be successfully parsed by `from_bon8`.
Example
```
#include <iostream>
#include <iomanip>
#include <nlohmann/json.hpp>
using json = nlohmann::json;
int main()
{
// create byte vector
std::vector<std::uint8_t> v = {0x89, 0x63, 0x6f, 0x6d, 0x70, 0x61, 0x63, 0x74,
0xf9, 0x66, 0x6f, 0x72, 0x6d, 0x61, 0x74, 0xff,
0x42, 0x4f, 0x4e, 0x38, 0xff, 0x73, 0x63, 0x68,
0x65, 0x6d, 0x61, 0x90
};
// deserialize it with BON8
json j = json::from_bon8(v);
// print the deserialized JSON value
std::cout << std::setw(2) << j << std::endl;
}
```
Output:
```
{
"compact": true,
"format": "BON8",
"schema": 0
}
```