json/docs/mkdocs/docs/api/basic_json/is_boolean.md

nlohmann::basic_json::is_boolean

constexpr bool is_boolean() const noexcept;

This function returns #!cpp true if and only if the JSON value is #!json true or #!json false.

Return value

#!cpp true if type is boolean, #!cpp false otherwise.

Exception safety

No-throw guarantee: this member function never throws exceptions.

Complexity

Constant.

Examples

??? example

The following code exemplifies `is_boolean()` for all JSON types.

```cpp
--8<-- "examples/is_boolean.cpp"
```

Output:

```json
--8<-- "examples/is_boolean.output"
```

See also

• boolean_t the type used to store JSON booleans
• is_primitive checks whether the JSON value is primitive
• basic_json_view::is_boolean - the same check on a zero-copy view

Version history

• Added in version 1.0.0.