std:: equal_to<void>

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C++
Utilities library
General utilities
Relational operators (deprecated in C++20)
Function objects
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(C++17) (C++23)
Identity function object
(C++20)
Old binders and adaptors
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( until C++17* )
( until C++17* ) ( until C++17* ) ( until C++17* ) ( until C++17* )
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Defined in header <functional>
template <>
class equal_to < void > ;
(since C++14)

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

Nested types

Nested type Definition
is_transparent unspecified

Member functions

operator()
tests if the two arguments compare equal
(public member function)

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

template < class T, class U >

constexpr auto operator ( ) ( T && lhs, U && rhs ) const

- > decltype ( std:: forward < T > ( lhs ) == std:: forward < U > ( rhs ) ) ;

Returns the result of equality comparison between lhs and rhs .

Parameters

lhs, rhs - values to compare

Return value

std:: forward < T > ( lhs ) == std:: forward < U > ( rhs ) .

Example

Run this code 
#include <functional>
 
int main()
{
    constexpr int a = 0, b = 8;
    std::equal_to<> equal{};
    static_assert(equal(a, a));
    static_assert(!equal(a, b));
}
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