std:: negate<void>

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C++
Utilities library
General utilities
Relational operators (deprecated in C++20)
Function objects
Function invocation
(C++17) (C++23)
Identity function object
(C++20)
Old binders and adaptors
( until C++17* )
( until C++17* )
( until C++17* )
( until C++17* )
( until C++17* )
( until C++17* )
( until C++17* ) ( until C++17* ) ( until C++17* ) ( until C++17* )
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( until C++17* ) ( until C++17* )
( until C++17* ) ( until C++17* )

( until C++17* )
( until C++17* ) ( until C++17* ) ( until C++17* ) ( until C++17* )
( until C++20* )
( until C++20* )
Defined in header <functional>
template <>
class negate < void > ;
(since C++14)

std:: negate <> is a specialization of std::negate with parameter and return type deduced.

Member types

Type Definition
is_transparent unspecified

Member functions

operator()
returns its negated argument
(public member function)

std::negate<void>:: operator()

template < class T >

constexpr auto operator ( ) ( T && arg ) const

- > decltype ( - std:: forward < T > ( arg ) ) ;

Returns the result of negating arg .

Parameters

arg - value to negate

Return value

- std:: forward < T > ( arg ) .

Example

Run this code 
#include <complex>
#include <functional>
#include <iostream>
 
int main()
{
    auto complex_negate = std::negate<void>{}; // “void” can be omitted
    constexpr std::complex z(4, 2);
    std::cout << z << '\n';
    std::cout << -z << '\n';
    std::cout << complex_negate(z) << '\n';
}

Output: 

(4,2)
(-4,-2)
(-4,-2)
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