std::experimental::ranges::not_equal_to (3) - Linux Manuals

std::experimental::ranges::not_equal_to: std::experimental::ranges::not_equal_to


std::experimental::ranges::not_equal_to - std::experimental::ranges::not_equal_to


Defined in header <experimental/ranges/functional>
template< class T = void >
requires EqualityComparable<T> ||
Same<T, void> || (ranges TS)
/* == on two const T lvalues invokes a built-in operator comparing pointers */
struct not_equal_to;
template <> (ranges TS)
struct not_equal_to<void>;

Function object for performing comparisons. The primary template invokes operator == on const lvalues of type T and negates the result. The specialization not_equal_to<void> deduces the parameter types of the function call operator from the arguments (but not the return type).
All specializations of not_equal_to are Semiregular.

Member types

Member type Definition
is_transparent (member only of not_equal_to<void> specialization) /* unspecified */

Member functions

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


constexpr bool operator()(const T& x, const T& y) const; (1) (member only of primary not_equal_to<T> template)
template< class T, class U >
requires EqualityComparableWith<T, U> ||
/* std::declval<T>() == std::declval<U>() resolves to (2) (member only of not_equal_to<void> specialization)
a built-in operator comparing pointers */
constexpr bool operator()(T&& t, U&& u) const;

1) Compares x and y. Equivalent to return !ranges::equal_to<>{}(x, y);
2) Compares t and u. Equivalent to return !ranges::equal_to<>{}(std::forward<T>(t), std::forward<U>(u));.


Unlike std::not_equal_to, ranges::not_equal_to requires both == and != to be valid (via the EqualityComparable and EqualityComparableWith constraints), and is entirely defined in terms of ranges::equal_to. However, the implementation is free to use operator!= directly, because those concepts require the results of == and != to be consistent.


 This section is incomplete
 Reason: no example

See also

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