C++ future的其他成员

future.status枚举类型，

enum class future_status { // names for timed wait function returns
    ready,
    timeout,
    deferred
};

using namespace std;

int mythread() {
    cout << "thread id = " << this_thread::get_id() << endl;
    chrono::milliseconds drue(5000);
    std::this_thread::sleep_for(drue);
    cout << "thread id = " << this_thread::get_id() << endl;
    return 5;
}
int main()
{
    cout << "main id" << this_thread::get_id() << endl;
    future result = async(mythread);
    cout << "countinue......" << endl;
    //cout << result.get() << endl;
    future_status statu = result.wait_for(std::chrono::seconds(1));
    if (statu == std::future_status::timeout) {
        cout << "超时，子线程还没有执行完毕" << endl;
    }
    cout << "i love china" << endl;
    return 0;
}

std::future.wait_for()等待子线程的时间，如果在等待时间内子线程没有结束，则返回std::status::timeout。