std::experimental::ranges::not_equal_to

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Experimental
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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>

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 !=

Example

See also

function object implementing x != y
(class template)