（某培训机构的练习题）子线程循环 10 次，接着主线程循环 100 次，接着又回到子线程循环 10 次，接着再回到主线程又循环 100 次，如此循环50次，试写出代码。
从题目看，首先想到是使用条件变量来实现，以下是实现代码：
1 #include <iostream> 2 #include <stdlib.h> 3 #include <pthread.h> 4 using namespace std; 5 6 pthread_mutex_t myloack=PTHREAD_MUTEX_INITIALIZER; 7 pthread_cond_t mycond=PTHREAD_COND_INITIALIZER; 8 int n=0; 9 void *TreadFuncMa(void *arg) 10 { 11 for (int i = 0; i < 50; ++i) 12 { 13 pthread_mutex_lock(&myloack); 14 15 if(n!=0) 16 pthread_cond_wait(&mycond,&myloack); 17 18 for (int i = 0; i < 10; ++i) 19 cout<<"A"<<" "; 20 21 cout<<endl; 22 n++; 23 24 pthread_mutex_unlock(&myloack); 25 pthread_cond_broadcast(&mycond); 26 } 27 return (void *)0; 28 } 29 int main(int argc, char const *argv[]) 30 { 31 pthread_t id; 32 int ret=pthread_create(&id,NULL,TreadFuncMa,NULL); 33 if (rt!=0) 34 { 35 return 0; 36 } 37 38 /* code */ 39 for (int i = 0; i < 50; ++i) 40 { 41 pthread_mutex_lock(&myloack); 42 43 if(n!=1) 44 pthread_cond_wait(&mycond,&myloack); 45 46 for (int i = 0; i < 100; ++i) 47 cout<<"B"<<" "; 48 49 cout<<endl; 50 n--; 51 52 pthread_mutex_unlock(&myloack); 53 pthread_cond_broadcast(&mycond); 54 } 55 pthread_join(id,NULL); 56 return 0; 57 }
