# std::experimental::negation

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< cpp‎ | experimental

Defined in header `<experimental/type_traits>` |  |
template<class B> struct negation; | (1) | (library fundamentals TS v2)

Forms the logical negation of the type trait `B`.

The type negation<B> is a UnaryTypeTrait with a BaseCharacteristic of std::integral_constant<bool, !bool(B::value)>.

### Template parameters

B | - | any type such that the expression bool(B::value) is a valid constant expression

### Helper variable template

template<class B> constexpr bool negation_v = negation<B>::value; |  | (library fundamentals TS v2)

## Inherited from std::integral_constant

### Member constants

value [static] | true if `B` has a member `::value` such that !bool(B::value) is true , false otherwise (public static member constant)

### Member functions

operator bool | converts the object to bool, returns `value` (public member function)
operator() (C++14) | returns `value` (public member function)

### Member types

Type | Definition
`value_type` | `bool`
`type` | std::integral_constant<bool, value>

### Possible implementation

    template<class B>
    struct negation : std::integral_constant<bool, !bool(B::value)> { };

### Example

| This section is incomplete Reason: no example

### See also

negation (C++17) | logical NOT metafunction (class template)

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