# std::stop_token::stop_requested

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< cpp‎ | thread‎ | stop token

bool stop_requested() const noexcept; |  | (since C++20)

Checks if the `stop_token` object has associated stop-state and that state has received a stop request. A default constructed stop_token has no associated stop-state, and thus has not had stop requested.

### Parameters

(none)

### Return value

true if the stop_token object has associated stop-state and it received a stop request, false otherwise.

### Example

Run this code

    #include <chrono>
    #include <condition_variable>
    #include <iostream>
    #include <mutex>
    #include <string_view>
    #include <thread>
    using namespace std::chrono_literals;

    int main()
    {
        std::cout << std::boolalpha;
        auto print = [](std::string_view name, const std::stop_token& token)
        {
            std::cout << name << ": stop_possible = " << token.stop_possible();
            std::cout << ", stop_requested = " << token.stop_requested() << '\n';
        };

        // A worker thread that will listen to stop requests
        auto stop_worker = std::jthread([](std::stop_token stoken)
        {
            for (int i = 10; i; --i)
            {
                std::this_thread::sleep_for(300ms);
                if (stoken.stop_requested())
                {
                    std::cout << "  Sleepy worker is requested to stop\n";
                    return;
                }
                std::cout << "  Sleepy worker goes back to sleep\n";
            }
        });

        // A worker thread that will only stop when completed
        auto inf_worker = std::jthread([]()
        {
            for (int i = 5; i; --i)
            {
                std::this_thread::sleep_for(300ms);
                std::cout << "  Run as long as we want\n";
            }
        });

        std::stop_token def_token;
        std::stop_token stop_token = stop_worker.get_stop_token();
        std::stop_token inf_token = inf_worker.get_stop_token();
        print("def_token ", def_token);
        print("stop_token", stop_token);
        print("inf_token ", inf_token);

        std::cout << "\nRequest and join stop_worker:\n";
        stop_worker.request_stop();
        stop_worker.join();

        std::cout << "\nRequest and join inf_worker:\n";
        inf_worker.request_stop();
        inf_worker.join();
        std::cout << '\n';

        print("def_token ", def_token);
        print("stop_token", stop_token);
        print("inf_token ", inf_token);
    }

Possible output:

    def_token : stop_possible = false, stop_requested = false
    stop_token: stop_possible = true, stop_requested = false
    inf_token : stop_possible = true, stop_requested = false

    Request and join stop_worker:
      Run as long as we want
      Sleepy worker is requested to stop

    Request and join inf_worker:
      Run as long as we want
      Run as long as we want
      Run as long as we want
      Run as long as we want

    def_token : stop_possible = false, stop_requested = false
    stop_token: stop_possible = true, stop_requested = true
    inf_token : stop_possible = true, stop_requested = true

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