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Conflicts in the See also lists of nine basic_json pages, is_discarded.md, and features/index.md, where develop (#5638) and this branch both added entries: kept both. Ran make amalgamate. Signed-off-by: Niels Lohmann <mail@nlohmann.me>
1019 B
1019 B
nlohmann::basic_json::is_null
constexpr bool is_null() const noexcept;
This function returns #!cpp true if and only if the JSON value is #!json null.
Return value
#!cpp true if type is #!json null, #!cpp false otherwise.
Exception safety
No-throw guarantee: this member function never throws exceptions.
Complexity
Constant.
Examples
??? example
The following code exemplifies `is_null()` for all JSON types.
```cpp
--8<-- "examples/is_null.cpp"
```
Output:
```json
--8<-- "examples/is_null.output"
```
See also
- is_array checks whether the JSON value is an array
- is_object checks whether the JSON value is an object
- type returns the type of the JSON value
- value_t the enumeration of JSON types
- basic_json_view::is_null - the same check on a zero-copy view
Version history
- Added in version 1.0.0.