std::ranges::not_equal_to(3)

NAME
std::ranges::not_equal_to - std::ranges::not_equal_to

Synopsis
   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).
  Implementation-defined strict total order over pointers
   The function call operator yields the implementation-defined strict total order over
   pointers if the = operator between arguments invokes a built-in comparison operator
   for a pointer, even if the built-in = operator does not.
   The implementation-defined strict total order is consistent with the partial order
   imposed by built-in comparison operators (<=>, <, >, <=, and >=), and consistent
   among following standard function objects:
     * std::less, std::greater, std::less_equal, and std::greater_equal, when the
       template argument is a pointer type or void
     * std::ranges::equal_to, std::ranges::not_equal_to, std::ranges::less,
       std::ranges::greater, std::ranges::less_equal, std::ranges::greater_equal, and
       std::compare_three_way

Member types
   Member 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 >
   requires std::equality_comparable_with<T, U> // with different sematic
   requirements
   constexpr bool operator()(T&& t, U&& u) const;
   Compares t and u. Equivalent to return !ranges::equal_to{}(std::forward<T>(t),
   std::forward<U>(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 only semantic requirements
                       comparing pointers relaxed

See also
   not_equal_to function object implementing x != y
                (class template)