std::totally_ordered, std::totally_ordered_with

Since C++20

Header: <concepts>

  1. The concept std::totally_ordered specifies that the comparison operators ==,!=,<,>,<=,>= on a type yield results consistent with a strict total order on the type.

# Declarations

template< class T >
concept totally_ordered =
std::equality_comparable<T> && __PartiallyOrderedWith<T, T>;

(since C++20)

template< class T, class U >
concept totally_ordered_with =
std::totally_ordered<T> &&
std::totally_ordered<U> &&
std::equality_comparable_with<T, U> &&
std::totally_ordered<
std::common_reference_t<
const std::remove_reference_t<T>&,
const std::remove_reference_t<U>&>> &&
__PartiallyOrderedWith<T, U>;

(since C++20)

Helper concepts

template< class T, class U >
concept __PartiallyOrderedWith =
requires(const std::remove_reference_t<T>& t,
const std::remove_reference_t<U>& u) {
{ t < u } -> boolean-testable;
{ t > u } -> boolean-testable;
{ t <= u } -> boolean-testable;
{ t >= u } -> boolean-testable;
{ u < t } -> boolean-testable;
{ u > t } -> boolean-testable;
{ u <= t } -> boolean-testable;
{ u >= t } -> boolean-testable;
};

(exposition only*)

# See also