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InterviewGuide 勘误 #128

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laoyoutiao237 opened this issue Aug 2, 2023 · 0 comments

laoyoutiao237 commented Aug 2, 2023

面试高频算法真题里 11、写三个线程交替打印ABC
原解答为：

void printa(){
    unique_lock<mutex> lk(mymutex); //此处加锁的位置不对
    int count=0;
    while(count<10){
        while(flag!=0) cv.wait(lk);
        cout<<"thread 1: a"<<endl;
        flag=1;
        cv.notify_all();
        count++;
    }
    cout<<"my thread 1 finish"<<endl;
}

应将加锁位置改为while循环内

void printa(){
    
    int count=0;
    while(count<10){
        unique_lock<mutex> lk(mymutex); //此处加锁
        while(flag!=0) cv.wait(lk);
        cout<<"thread 1: a"<<endl;
        flag=1;
        cv.notify_all();
        count++;
    }
    cout<<"my thread 1 finish"<<endl;
}

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