# std::swap(std::array)

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< cpp‎ | container‎ | array

Defined in header `<array>` |  |
template< class T, std::size_t N > void swap( std::array<T, N>& lhs, std::array<T, N>& rhs ); |  | (since C++11) (until C++17)
template< class T, std::size_t N > void swap( std::array<T, N>& lhs, std::array<T, N>& rhs ) noexcept(/* see below */); |  | (since C++17) (until C++20)
template< class T, std::size_t N > constexpr void swap( std::array<T, N>& lhs, std::array<T, N>& rhs ) noexcept(/* see below */); |  | (since C++20)

Specializes the std::swap algorithm for std::array. Swaps the contents of lhs and rhs. Calls lhs.swap(rhs).

This overload participates in overload resolution only if N == 0 or std::is_swappable_v<T> is true. | (since C++17)

### Parameters

lhs, rhs | - | containers whose contents to swap

### Return value

(none)

### Complexity

Linear in size of the container.

### Exceptions

`noexcept` specification: noexcept(noexcept(lhs.swap(rhs))) | (since C++17)

### Notes

Although the overloads of std::swap for container adaptors are introduced in C++11, container adaptors can already be swapped by std::swap in C++98. Such calls to std::swap usually have linear time complexity, but better complexity may be provided.

### Example

Run this code

    #include <algorithm>
    #include <iostream>
    #include <array>

    int main()
    {
        std::array<int, 3> alice{1, 2, 3};
        std::array<int, 3> bob{7, 8, 9};

        auto print = [](const int& n) { std::cout << ' ' << n; };

        // Print state before swap
        std::cout << "alice:";
        std::for_each(alice.begin(), alice.end(), print);
        std::cout << "\n" "bob  :";
        std::for_each(bob.begin(), bob.end(), print);
        std::cout << '\n';

        std::cout << "-- SWAP\n";
        std::swap(alice, bob);

        // Print state after swap
        std::cout << "alice:";
        std::for_each(alice.begin(), alice.end(), print);
        std::cout << "\n" "bob  :";
        std::for_each(bob.begin(), bob.end(), print);
        std::cout << '\n';
    }

Output:

    alice: 1 2 3
    bob  : 7 8 9
    -- SWAP
    alice: 7 8 9
    bob  : 1 2 3

### See also

swap (C++11) | swaps the contents (public member function)

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