std::negation
From cppreference.com
                    
                                        
                    
                    
                                                            
                    | Defined in header  <type_traits> | ||
| template<class B> struct negation; | (1) | (since C++17) | 
Forms the logical negation of the type trait B.
The type std::negation<B> is a UnaryTypeTrait with a BaseCharacteristic of std::integral_constant<bool, !B::value>.
| Contents | 
[edit] Template parameters
| B | - | any type such that B::value is convertible to bool | 
[edit] Helper variable template
| template<class B> constexpr bool negation_v = negation<B>::value; | (since C++17) | |
Inherited from std::integral_constant
Member constants
| value [static] | true if Bhas a member::valuethat is false , 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> | 
[edit] Possible implementation
| template<class B> struct negation : std::bool_constant<!B::value> { }; | 
[edit] Example
| This section is incomplete Reason: no example | 
[edit] See also
| (C++17) | variadic logical AND metafunction (class template) | 
| (C++17) | variadic logical OR metafunction (class template) | 


