std::pair<T1,T2>::swap

 

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std::pair

Member functions

pair::pair

pair::operator=

pair::swap

Non-member functions

make_pair

operator==operator!=operator<operator<=operator>operator>=operator<=> (until C++20)(until C++20)(until C++20)(until C++20)(until C++20)(C++20)

std::swap

get (C++11)

Deduction guides(C++17)

Helper classes

tuple_size (C++11)

tuple_element (C++11)

 

void swap(pair& other) noexcept(/* see below */);		(since C++11) (until C++20)
constexpr void swap(pair& other) noexcept(/* see below */);		(since C++20)

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

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_v<first_type> &&      std::is_nothrow_swappable_v<second_type> )	(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)