std::logical_not (3) - Linux Manuals

std::logical_not: std::logical_not


std::logical_not - std::logical_not


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

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


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.

                  function object implementing !x deducing argument and return types (since C++14)
logical_not<void> (class template specialization)

Member types

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

Member functions

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


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

Returns the logical NOT of arg.


arg - value to compute logical NOT of

Return value

The result of !arg.



Possible implementation

  const bool operator()(const T &arg) const
      return !arg;