[pairs.spec]

# 22 General utilities library [[utilities]](./#utilities)

## 22.3 Pairs [[pairs]](pairs#spec)

### 22.3.3 Specialized algorithms [pairs.spec]

[ð](#lib:operator==,pair)

`template<class T1, class T2, class U1, class U2>
  constexpr bool operator==(const pair<T1, T2>& x, const pair<U1, U2>& y);
`

[1](#1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L1305)

*Constraints*: x.first == y.first and x.second == y.second are
valid expressions and
each of decltype(x.first == y.first) anddecltype(x.second == y.second) models *boolean-  
testable*[.](#1.sentence-1)

[2](#2)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L1312)

*Returns*: x.first == y.first && x.second == y.second[.](#2.sentence-1)

[ð](#lib:operator%3c=%3e,pair)

`template<class T1, class T2, class U1, class U2>
  constexpr common_comparison_category_t<synth-three-way-result<T1, U1>,
                                         synth-three-way-result<T2, U2>>
    operator<=>(const pair<T1, T2>& x, const pair<U1, U2>& y);
`

[3](#3)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L1326)

*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);

[ð](#lib:swap,pair)

`template<class T1, class T2>
  constexpr void swap(pair<T1, T2>& x, pair<T1, T2>& y) noexcept(noexcept(x.swap(y)));
template<class T1, class T2>
  constexpr void swap(const pair<T1, T2>& x, const pair<T1, T2>& y) noexcept(noexcept(x.swap(y)));
`

[4](#4)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L1344)

*Constraints*: 

- [(4.1)](#4.1)

  For the first overload,is_swappable_v<T1> is true andis_swappable_v<T2> is true[.](#4.1.sentence-1)

- [(4.2)](#4.2)

  For the second overload,is_swappable_v<const T1> is true andis_swappable_v<const T2> is true[.](#4.2.sentence-1)

[5](#5)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L1357)

*Effects*: Equivalent to x.swap(y)[.](#5.sentence-1)

[ð](#lib:make_pair)

`template<class T1, class T2>
  constexpr pair<unwrap_ref_decay_t<T1>, unwrap_ref_decay_t<T2>> make_pair(T1&& x, T2&& y);
`

[6](#6)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L1369)

*Returns*: pair<unwrap_ref_decay_t<T1>,
 unwrap_ref_decay_t<T2>>(std::forward<T1>(x), std::forward<T2>(y))

[7](#7)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L1377)

[*Example [1](#example-1)*:

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

â *end example*]
