std::experimental::ranges::not_equal_to

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Technical Specifications

Technical specifications

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swap	exchange
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invoke identity	equal_to not_equal_to	greater less	greater_equal less_equal
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is_swappable_withis_swappable	is_nothrow_swappable_withis_nothrow_swappable	common_reference common_type
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Defined in header <experimental/ranges/functional>
template< class T = void > requires EqualityComparable<T> || Same<T, void> || /* == on two const T lvalues invokes a built-in operator comparing pointers */ struct not_equal_to;		(ranges TS)
template <> struct not_equal_to<void>;		(ranges TS)

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

operator()

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

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

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 a built-in operator comparing pointers */ constexpr bool operator()(T&& t, U&& u) const;	(2)	(member only of not_equal_to<void> specialization)

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));.

Notes

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.

See also

not_equal_to

function object implementing x != y (class template)