NAME¶

std::less_equal - std::less_equal

Synopsis¶

Defined in header <functional>
template<> (since C++14)
class less_equal<void>;

std::less_equal<void> is a specialization of std::less_equal with parameter and
return type deduced.

Member functions¶

operator() tests if lhs compares less or equal than rhs
(public member function)

std::less_equal<void>::operator()

template< class T, class U >

constexpr auto operator()( T&& lhs, U&& rhs ) const

-> decltype(std::forward<T>(lhs) <= std::forward<U>(rhs));

Returns the result of std::forward<T>(lhs) <= std::forward<U>(rhs).

Parameters¶

lhs, rhs - values to compare

Return value¶

std::forward<T>(lhs) <= std::forward<U>(rhs).

If a built-in operator comparing pointers is called, the result is consistent with
the implementation-defined strict total order over pointers.

Exceptions¶

May throw implementation-defined exceptions.

Example¶

// Run this code

#include <algorithm>
#include <functional>
#include <initializer_list>

constexpr bool strictly_not_positive(int lhs)
{
return std::less_equal<>()(lhs, 0);
}

int main()
{
constexpr int low = 0, high = 8;
std::less_equal<> less_equal{};
static_assert(less_equal(low, high));
static_assert(less_equal(low, low));

static constexpr auto arr = {1, 0, -1, -2, -3, -4};
static_assert(!std::all_of(arr.begin(), arr.end(), strictly_not_positive));
static_assert(std::all_of(arr.begin() + 1, arr.end(), strictly_not_positive));
}

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 2562 C++98 the pointer total order might be guaranteed to be consistent
inconsistent