std::not_equal_to<void> - cppreference.com

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`template<> class not_equal_to<void>;`		(since C++14)

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

Nested types

Member functions

tests if the two arguments do not compare equal
(public member function)

std::not_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 non-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 p = 0, q = 8;
    std::not_equal_to<> not_equal{};
    static_assert(!not_equal(p, p));
    static_assert(not_equal(p, q));
}