# swap(std::jthread)

From cppreference.com
< cpp‎ | thread‎ | jthread

friend void swap( jthread &lhs, jthread &rhs ) noexcept; |  | (since C++20)

Overloads the std::swap algorithm for std::jthread. Exchanges the state of `lhs` with that of `rhs`. Effectively calls lhs.swap(rhs). This function is not visible to ordinary unqualified or qualified lookup, and can only be found by argument-dependent lookup when `std::jthread` is an associated class of the arguments.

### Parameters

lhs, rhs | - | jthreads whose states to swap

### Return value

(none)

### Example

Run this code

    #include <iostream>
    #include <thread>
    #include <chrono>

    void foo()
    {
        std::this_thread::sleep_for(std::chrono::seconds(1));
    }

    void bar()
    {
        std::this_thread::sleep_for(std::chrono::seconds(1));
    }

    int main()
    {
        using std::swap;

        std::jthread t1(foo);
        std::jthread t2(bar);

        std::cout << "thread 1 id: " << t1.get_id() << '\n'
                  << "thread 2 id: " << t2.get_id() << '\n';

        swap(t1, t2);

        std::cout << "after std::swap(t1, t2):" << '\n'
                  << "thread 1 id: " << t1.get_id() << '\n'
                  << "thread 2 id: " << t2.get_id() << '\n';

        t1.swap(t2);

        std::cout << "after t1.swap(t2):" << '\n'
                  << "thread 1 id: " << t1.get_id() << '\n'
                  << "thread 2 id: " << t2.get_id() << '\n';

    }

Possible output:

    thread 1 id: 1892
    thread 2 id: 2584
    after std::swap(t1, t2):
    thread 1 id: 2584
    thread 2 id: 1892
    after t1.swap(t2):
    thread 1 id: 1892
    thread 2 id: 2584

### See also

swap | swaps two jthread objects (public member function)

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