mirror of
https://github.com/nlohmann/json.git
synced 2026-09-30 14:05:18 +00:00
9856da2561
- API pages for get, get_to, get_string, number_token, and value of basic_json_view; JSON pointer overloads of operator[], at, and contains; links both ways with the basic_json pages - the feature page describes which conversions copy nothing - the examples show when the view helps: strings without copies, numbers exactly as written, and paths into a large text Signed-off-by: Niels Lohmann <mail@nlohmann.me>
1.9 KiB
1.9 KiB
nlohmann::basic_json::get_ref
template<typename ReferenceType>
ReferenceType get_ref();
template<typename ReferenceType>
const ReferenceType get_ref() const;
Implicit reference access to the internally stored JSON value. No copies are made.
Template parameters
ReferenceType- reference type; must be a reference to
array_t,object_t,string_t,boolean_t,number_integer_t, ornumber_unsigned_t,number_float_t, orbinary_t. Enforced by a static assertion.
Return value
reference to the internally stored JSON value if the requested reference type fits to the JSON value; throws
type_error.303 otherwise
Exception safety
Strong exception safety: if an exception occurs, the original value stays intact.
Exceptions
Throws type_error.303 if the requested reference type does not
match the stored JSON value type; example: "incompatible ReferenceType for get_ref, actual type is binary".
Complexity
Constant.
Notes
!!! danger "Undefined behavior"
The reference becomes invalid if the underlying JSON object changes.
Examples
??? example
The example shows several calls to `get_ref()`.
```cpp
--8<-- "examples/get_ref.cpp"
```
Output:
```json
--8<-- "examples/get_ref.output"
```
See also
- get_ptr() get a pointer value
- basic_json_view::get_string - the closest counterpart on a zero-copy view: a string without a copy, but as a view rather than a reference to a value that must already exist
Version history
- Added in version 1.1.0.
- Extended to binary types in version 3.8.0.