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std::strong_order

From natekohl.net
< cpp‎ | utility
 
 
 
Defined in header <compare>
template< class T >
constexpr std::strong_ordering strong_order(const T& a, const T& b);
(since C++20)

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

Specifically,

  • First, 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, if the expression a <=> b is well-formed and its result is convertible to std::strong_ordering, returns that result.
  • Otherwise, if the expression a <=> b is well-formed, but its result is not convertible to std::strong_ordering, then the function is defined as deleted.
  • Otherwise, if the expression a <=> b is ill-formed, but the expressions a == b and a < b are both well-formed and convertible to bool,
  • if a == b is true, returns std::strong_ordering::equal
  • otherwise, if a < b is true, returns std::strong_ordering::less
  • otherwise, returns std::strong_ordering::greater
  • Otherwise, the function is defined as deleted.

Contents

[edit] Parameters

a, b - values to compare

[edit] Return value

A value of type std::strong_ordering, as described above.

[edit] Notes

[edit] Example

[edit] See also

the result type of 3-way comparison that supports all 6 operators and is substitutable
(class) [edit]
performs 3-way comparison and produces a result of type std::weak_ordering
(function template) [edit]