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@@ -12,8 +12,8 @@ T value(const json_pointer& ptr, const T& default_value) const;
string_t value(const json_pointer& ptr, const char* default_value) const;
```
1. Returns the value of the object member with key `key` -- the first one, should the key occur more than once (see
[Notes on duplicate keys](operator[].md#notes)) -- converted to `T`, or `default_value` if there is no such member.
1. Returns the value of the object member with key `key` — the first one, should the key occur more than once (see
[Notes on duplicate keys](operator[].md#notes)) — converted to `T`, or `default_value` if there is no such member.
2. Returns the value a JSON pointer `ptr` refers to, starting at this value, converted to `T`, or `default_value` if
`ptr` cannot be resolved.
@@ -48,16 +48,16 @@ Strong guarantee: there are no changes to the view or the document it refers to.
## Exceptions
1. Throws [`type_error.306`](../../home/exceptions.md#jsonexceptiontype_error306) if the value is not an object --
1. Throws [`type_error.306`](../../home/exceptions.md#jsonexceptiontype_error306) if the value is not an object —
the same exception, with the same message, that [`BasicJsonType::value`](../basic_json/value.md) throws for the
same call. If a member with key `key` is found, throws whatever converting it to `T` throws (typically
[`type_error.302`](../../home/exceptions.md#jsonexceptiontype_error302), with the same message
[`BasicJsonType::value`](../basic_json/value.md) throws for the same mismatch); a missing member never throws.
2. Throws [`type_error.306`](../../home/exceptions.md#jsonexceptiontype_error306) if this value -- not the value `ptr`
resolves to -- is neither an object nor an array. Throws [`parse_error.106`](../../home/exceptions.md#jsonexceptionparse_error106)
2. Throws [`type_error.306`](../../home/exceptions.md#jsonexceptiontype_error306) if this value — not the value `ptr`
resolves to — is neither an object nor an array. Throws [`parse_error.106`](../../home/exceptions.md#jsonexceptionparse_error106)
or [`parse_error.109`](../../home/exceptions.md#jsonexceptionparse_error109) if `ptr` contains a malformed array
index. If `ptr` resolves to a value, throws whatever converting it to `T` throws. Every other way `ptr` can fail to
resolve -- a missing key, an out-of-range or "`-`" array index, an unresolvable token on a primitive -- yields
resolve — a missing key, an out-of-range or "`-`" array index, an unresolvable token on a primitive — yields
`default_value` instead of throwing, exactly as [`BasicJsonType::value`](../basic_json/value.md) catches
`out_of_range` and returns `default_value`.
@@ -73,7 +73,7 @@ None of these exceptions carry a [`JSON_DIAGNOSTICS`](../macros/json_diagnostics
Objects with 128 or more members get a hash index of their keys while parsing, so that a lookup in them takes
constant time on average.
2. Linear in the number of reference tokens of `ptr` and, for each token, in the number of members of the object at
that level or the index into the array -- as for the [`operator[]`](operator[].md#complexity) and
that level or the index into the array — as for the [`operator[]`](operator[].md#complexity) and
[`at`](at.md#complexity) overloads that take a JSON pointer. Plus the complexity of converting the resolved value
to `T`.
@@ -89,7 +89,7 @@ None of these exceptions carry a [`JSON_DIAGNOSTICS`](../macros/json_diagnostics
!!! info "Differences to `at` and `operator[]`"
Unlike [`at`](at.md), this function does not throw if `key`/`ptr` resolves to no value. Unlike
[`operator[]`](operator[].md), it never returns a [discarded](is_discarded.md) view -- it always returns a `T` --
[`operator[]`](operator[].md), it never returns a [discarded](is_discarded.md) view — it always returns a `T` —
and it is available on any view, since it never needs to insert a missing element the way the non-const
`BasicJsonType::operator[]` would.
@@ -187,8 +187,8 @@ None of these exceptions carry a [`JSON_DIAGNOSTICS`](../macros/json_diagnostics
## See also
- [at](at.md) - access specified element with bounds checking (throws instead of returning a default value)
- [operator[]](operator[].md) - access specified element (returns a discarded view instead of a default value)
- [`at`](at.md) - access specified element with bounds checking (throws instead of returning a default value)
- [`operator[]`](operator[].md) - access specified element (returns a discarded view instead of a default value)
- [`BasicJsonType::value`](../basic_json/value.md) - the corresponding function of `basic_json`
## Version history