std::ranges::not_equal_to

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ranges::not_equal_to
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Defined in header <functional>
struct not_equal_to;
 (since C++20)

Function object for performing comparisons. Deduces the parameter types of the function call operator from the arguments (but not the return type).

Nested types

Nested type Definition
is_transparent unspecified

Member functions

operator()
 checks if the arguments are not equal
(public member function)

std::ranges::not_equal_to::operator()

template < class T, class U >
constexpr bool operator( ) ( T&& t, U&& u ) const ;

Equivalent to return ! ranges::equal_to { } ( std::forward <T> (t), std::forward <U> (u) ) ;

This overload participates in overload resolution only if std::equality_comparable_with<T, U>

Notes

Unlike std::not_equal_to, std::ranges::not_equal_to requires both == and != to be valid (via the equality_comparable_with constraint), and is entirely defined in terms of std::ranges::equal_to

Example

This section is incomplete
Reason: no example

Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

DR Applied to Behavior as published Correct behavior
LWG 3530 C++20 syntactic checks were relaxed while comparing pointers only semantic requirements are relaxed

See also

 function object implementing x != y
(class template)
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