NAME¶

std::strong_order - std::strong_order

Synopsis¶

Defined in header <compare>
inline namespace /* unspecified */ {

inline constexpr /* unspecified */ strong_order = /* unspecified (since C++20)
*/;

}
Call signature
template< class T, class U >

requires /* see below */

constexpr std::strong_ordering strong_order( T&& t, U&& u )
noexcept(/* see below */);

Compares two values using 3-way comparison and produces a result of type
std::strong_ordering.

Let t and u be expressions and T and U denote decltype((t)) and decltype((u))
respectively, std::strong_order(t, u) is expression-equivalent to:

* If std::is_same_v<std::decay_t<T>, std::decay_t<U>> is true:
* std::strong_ordering(strong_order(t, u)), if it is a well-formed expression
with overload resolution performed in a context that does not include a
declaration of std::strong_order,
* otherwise, if T is a floating-point type:
* if std::numeric_limits<T>::is_iec559 is true, performs the
ISO/IEC/IEEE 60559 totalOrder comparison of floating-point values and
returns that result as a value of type std::strong_ordering (note:
this comparison can distinguish between the positive and negative zero
and between the NaNs with different representations),
* otherwise, yields a value of type std::strong_ordering that is
consistent with the ordering observed by T's comparison operators,
* otherwise, std::strong_ordering(std::compare_three_way()(t, u)) if it is
well-formed.
* In all other cases, the expression is ill-formed, which can result in
substitution failure when it appears in the immediate context of a template
instantiation.

Example¶

This section is incomplete
Reason: no example

See also¶

strong_ordering the result type of 3-way comparison that supports all
(C++20) 6 operators and is substitutable
(class)
weak_order performs 3-way comparison and produces a result of
(C++20) type std::weak_ordering
(customization point object)
partial_order performs 3-way comparison and produces a result of
(C++20) type std::partial_ordering
(customization point object)
performs 3-way comparison and produces a result of
compare_strong_order_fallback type std::strong_ordering, even if operator<=> is
(C++20) unavailable
(customization point object)

Category:¶

* Todo no example