19 General utilities library [utilities]

19.4 Pairs [pairs]

19.4.3 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 bool operator!=(const pair<T1, T2>& x, const pair<T1, T2>& y);
2
#
Returns: !(x == y).
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template<class T1, class T2> constexpr bool operator<(const pair<T1, T2>& x, const pair<T1, T2>& y);
3
#
Returns: x.first < y.first || (!(y.first < x.first) && x.second < y.second).
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template<class T1, class T2> constexpr bool operator>(const pair<T1, T2>& x, const pair<T1, T2>& y);
4
#
Returns: y < x.
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template<class T1, class T2> constexpr bool operator<=(const pair<T1, T2>& x, const pair<T1, T2>& y);
5
#
Returns: !(y < x).
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template<class T1, class T2> constexpr bool operator>=(const pair<T1, T2>& x, const pair<T1, T2>& y);
6
#
Returns: !(x < y).
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template<class T1, class T2> void swap(pair<T1, T2>& x, pair<T1, T2>& y) noexcept(noexcept(x.swap(y)));
7
#
Effects: As if by x.swap(y).
8
#
Remarks: This function shall not participate in overload resolution unless is_­swappable_­v<T1> is true and is_­swappable_­v<T2> is true.
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template<class T1, class T2> constexpr pair<V1, V2> make_pair(T1&& x, T2&& y);
9
#
Returns: pair<V1, V2>(std​::​forward<T1>(x), std​::​forward<T2>(y)), where V1 and V2 are determined as follows: Let Ui be decay_­t<Ti> for each Ti.
If Ui is a specialization of reference_­wrapper, then Vi is Ui​::​type&, otherwise Vi is Ui.
10
#
[ 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
 ]