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

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< cpp‎ | utility‎ | pair

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)

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