std::weak_equal

 

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Defined in header <compare>
template< class T > constexpr std::weak_equality weak_equal(const T& a, const T& b);		(since C++20)

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

Specifically,

• If the expression a <=> b is well-formed and its result is convertible to std::weak_equality, returns that result.
• Otherwise, if the expression a <=> b is well-formed, but its result is not convertible to std::weak_equality, then the function is defined as deleted.
• Otherwise, if the expression a <=> b is ill-formed, but the expression a == b is well-formed and convertible to bool,

• if a == b is true, returns std::weak_equality::equivalent
• otherwise, returns std::weak_equality::nonequivalent

• Otherwise, the function is defined as deleted.

Parameters

a, b

-

values to compare

Return value

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

See also

weak_equality (C++20)	the result type of 3-way comparison that supports only equality/inequality and is not substitutable (class)
strong_equal (C++20)	performs 3-way comparison and produces a result of type std::strong_equality (function template)
strong_order (C++20)	performs 3-way comparison and produces a result of type std::strong_ordering (function template)
partial_order (C++20)	performs 3-way comparison and produces a result of type std::partial_ordering (function template)
weak_order (C++20)	performs 3-way comparison and produces a result of type std::weak_ordering (function template)