22 General utilities library [utilities]

22.10 Function objects [function.objects]

22.10.8 Comparisons [comparisons]

22.10.8.3 Class template not_equal_to [comparisons.not.equal.to]

template<class T = void> struct not_equal_to {
  constexpr bool operator()(const T& x, const T& y) const;
};

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constexpr bool operator()(const T& x, const T& y) const;

Returns: x != y.

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template<> struct not_equal_to<void> {
  template<class T, class U> constexpr auto operator()(T&& t, U&& u) const
    -> decltype(std::forward<T>(t) != std::forward<U>(u));

  using is_transparent = unspecified;
};

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template<class T, class U> constexpr auto operator()(T&& t, U&& u) const
    -> decltype(std::forward<T>(t) != std::forward<U>(u));

Returns: std::forward<T>(t) != std::forward<U>(u).