std::equal_to<void> - cppreference.com

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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

Member functions

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

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