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45 lines
845 B
Markdown
45 lines
845 B
Markdown
# <small>nlohmann::basic_json::</small>is_boolean
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```cpp
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constexpr bool is_boolean() const noexcept;
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```
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This function returns `#!cpp true` if and only if the JSON value is `#!json true` or `#!json false`.
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## Return value
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`#!cpp true` if type is boolean, `#!cpp false` otherwise.
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## Exception safety
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No-throw guarantee: this member function never throws exceptions.
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## Complexity
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Constant.
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## Examples
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??? example
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The following code exemplifies `is_boolean()` for all JSON types.
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```cpp
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--8<-- "examples/is_boolean.cpp"
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```
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Output:
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```json
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--8<-- "examples/is_boolean.output"
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```
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## See also
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- [boolean_t](boolean_t.md) the type used to store JSON booleans
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- [is_primitive](is_primitive.md) checks whether the JSON value is primitive
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## Version history
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- Added in version 1.0.0.
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