20 General utilities library [utilities]

20.4 Pairs [pairs]

20.4.3 Specialized algorithms [pairs.spec]

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template<class T1, class T2> constexpr bool operator==(const pair<T1, T2>& x, const pair<T1, T2>& y);
1
#
Returns: x.first == y.first && x.second == y.second.
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template<class T1, class T2> constexpr common_comparison_category_t<synth-three-way-result<T1>, synth-three-way-result<T2>> operator<=>(const pair<T1, T2>& x, const pair<T1, T2>& y);
2
#
Effects: Equivalent to: 
if (auto c = synth-three-way(x.first, y.first); c != 0) return c;
return synth-three-way(x.second, y.second);
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template<class T1, class T2> constexpr void swap(pair<T1, T2>& x, pair<T1, T2>& y) noexcept(noexcept(x.swap(y)));
3
#
Constraints: is_­swappable_­v<T1> is true and is_­swappable_­v<T2> is true.
4
#
Effects: Equivalent to x.swap(y).
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template<class T1, class T2> constexpr pair<unwrap_ref_decay_t<T1>, unwrap_ref_decay_t<T2>> make_pair(T1&& x, T2&& y);
5
#
Returns: 
pair<unwrap_ref_decay_t<T1>,
     unwrap_ref_decay_t<T2>>(std::forward<T1>(x), std::forward<T2>(y))
6
#
[Example
:
In place of: 
return pair<int, double>(5, 3.1415926);     // explicit types
a C++ program may contain: 
return make_pair(5, 3.1415926);             // types are deduced
— end example
]