std::logical_not

 

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Defined in header <functional>
template< class T > struct logical_not;		(until C++14)
template< class T = void > struct logical_not;		(since C++14)

Function object for performing logical NOT (logical negation). Effectively calls operator! for type T.

Specializations

The standard library provides a specialization of std::logical_not when T is not specified, which leaves the parameter types and return type to be deduced. logical_not<void> (C++14) function object implementing !x deducing parameter and return types (class template specialization)

(since C++14)

Member types

Type	Definition
result_type (deprecated in C++17)(removed in C++20)	bool
argument_type (deprecated in C++17)(removed in C++20)	T

These member types are obtained via publicly inheriting std::unary_function<T, bool>.

(until C++11)

Member functions

operator()

returns the logical NOT of the argument (public member function)

std::logical_not::operator()

bool operator()( const T& arg ) const;		(constexpr since C++14)

Returns the logical NOT of arg.

Parameters

arg

-

value to compute logical NOT of

Return value

The result of !arg.

Exceptions

May throw implementation-defined exceptions.

Possible implementation

constexpr // since C++14 bool operator()(const T& arg) const { return !arg; }