NAME¶

std::ranges::less_equal - std::ranges::less_equal

Synopsis¶

Defined in header <functional>
struct less_equal; (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 first argument is less than or equal to the second
(public member function)

std::ranges::less_equal::operator()

template< class T, class U >

requires std::totally_ordered_with<T, U> // with different semantic requirements

constexpr bool operator()(T&& t, U&& u) const;

Compares t and u. Equivalent to return !ranges::less{}(std::forward<U>(u),
std::forward<T>(t));.

Notes¶

Unlike std::less_equal, std::ranges::less_equal requires all six comparison
operators <, <=, >, >=, == and != to be valid (via the totally_ordered_with
constraint) and is entirely defined in terms of std::ranges::less.

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¶

less_equal function object implementing x <= y
(class template)