#include <iostream>                // std::cout

#include <thread>                // std::thread

#include <mutex>                // std::mutex, std::unique_lock

#include <condition_variable>    // std::condition_variable

std::mutex mtx;

std::condition_variable cv;

int cargo = ; // shared value by producers and consumers

void consumer()

{

    std::unique_lock < std::mutex > lck(mtx);

    while (cargo == )

        cv.wait(lck);

    std::cout << cargo << '\n';

    cargo = ;

}

void producer(int id)

{

    std::unique_lock < std::mutex > lck(mtx);

    cargo = id;

    cv.notify_one();//如果存在多个等待唤醒的线程则唤醒的线程时不确定的

}

int main()

{

    std::thread consumers[], producers[];

　　//多个生产者，多个消费者，只要加锁还是安全的

    // spawn 10 consumers and 10 producers:

    for (int i = ; i < ; ++i) {

        consumers[i] = std::thread(consumer);//消费者线程

        producers[i] = std::thread(producer, i + );//生产者线程

    }

    // join them back:

    for (int i = ; i < ; ++i) {

        producers[i].join();

        consumers[i].join();

    }

    getchar();

    return ;

}