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

nlohmann::basic_json::is_number

constexpr bool is_number() const noexcept;

This function returns #!cpp true if and only if the JSON value is a number. This includes both integer (signed and unsigned) and floating-point values.

Return value

#!cpp true if type is number (regardless whether integer, unsigned integer or floating-type), #!cpp false otherwise.

Exception safety

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

Complexity

Constant.

Possible implementation

constexpr bool is_number() const noexcept
{
    return is_number_integer() || is_number_float();
}

Examples

??? example

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

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

Output:

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

See also

• is_number_integer() check if value is an integer or unsigned integer number
• is_number_unsigned() check if value is an unsigned integer number
• is_number_float() check if value is a floating-point number

Version history

• Added in version 1.0.0.
• Extended to also return #!cpp true for unsigned integers in 2.0.0.