constexpr bool is_null() const noexcept;

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

#!cpp true if type is #!json null, #!cpp false otherwise.

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

Constant.

??? example

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

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

Output:

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

• Added in version 1.0.0.