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40 lines
636 B
Markdown
40 lines
636 B
Markdown
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# basic_json::is_null
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```cpp
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constexpr bool is_null() const noexcept;
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```
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This function returns `#!cpp true` if and only if the JSON value is `#!json null`.
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## Return value
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`#!cpp true` if type is `#!json null`, `#!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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## Example
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??? example
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The following code exemplifies `is_null()` for all JSON types.
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```cpp
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--8<-- "examples/is_null.cpp"
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```
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Output:
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```json
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--8<-- "examples/is_null.output"
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```
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## Version history
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- Added in version 1.0.0.
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