C++笔试题之两个线程轮流（交替）打印A和B

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这里使用C++11的线程语法来实现，一个线程打印A，一个线程打印B，交替进行。

#include <thread>
#include <iostream>
#include <mutex>
#include <condition_variable>

std::mutex data_mutex;
std::condition_variable data_var;
bool flag = true;

void printA()
{
    while(1)
    {
        std::this_thread::sleep_for(std::chrono::seconds(1));
        std::unique_lock<std::mutex> lck(data_mutex) ;
        data_var.wait(lck,[]{return flag;});
        std::cout<<"thread: "<< std::this_thread::get_id() << "   printf: " << "A" <<std::endl;
        flag = false;
        data_var.notify_one();
    }
}

void printB()
{
    while(1)
    {
        std::unique_lock<std::mutex> lck(data_mutex) ;
        data_var.wait(lck,[]{return !flag;});
        std::cout<<"thread: "<< std::this_thread::get_id() << "   printf: " << "B" <<std::endl;
        flag = true;
        data_var.notify_one();
    }
}

int main()
{
    std::thread tA(printA);
    std::thread tB(printB);
    tA.join();
    tB.join();
    return 0;
}

这个相当于始终只生产一个产品的生产者和消费者模型，关于C++11实现的生产者和消费者，详见：

https://blog.csdn.net/caoshangpa/article/details/53179154