std::pair::swap

 

C++

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optional

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in_placein_place_typein_place_indexin_place_tin_place_type_tin_place_index_t

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pair

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std::pair

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pair::pair

pair::operator=

pair::swap

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make_pair

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std::swap

get (C++11)

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void swap(pair& other) noexcept(/* see below */);		(since C++11)

Swaps first with other.first and second with other.second.

This function does not participate in overload resolution unless std::is_swappable_v<first_type> && std::is_swappable_v<second_type> is true.

(since C++17)

Parameters

other

-

pair of values to swap

Return value

(none)

Exceptions

noexcept specification:   noexcept(      noexcept(swap(first, other.first)) &&      noexcept(swap(second, other.second)) ) In the expression above, the identifier swap is looked up in the same manner as the one used by the C++17 std::is_nothrow_swappable trait.	(until C++17)
noexcept specification:   noexcept(      std::is_nothrow_swappable<first_type>::value) &&      std::is_nothrow_swappable<second_type>::value) )	(since C++17)

Example

Run this code

#include <iostream>
#include <utility>
#include <string>
int main()
{
    std::pair<int, std::string> p1, p2;
    p1 = std::make_pair(10, "test");
    p2.swap(p1);
    std::cout << "(" << p2.first << ", " << p2.second << ")\n";
}

Output:

(10, test)

Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

DR	Applied to	Behavior as published	Correct behavior
LWG 2456	C++11	the noexcept specification is ill-formed	made to work

See also

swap	swaps the values of two objects (function template)