table of contents
std::ranges::not_equal_to(3) | C++ Standard Libary | 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)
2022.07.31 | http://cppreference.com |