C多线程练习题

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题目：

子线程循环 3 次，接着主线程循环 6 次，接着又回到子线程循环 3 次，接着再回到主线程又循环6 次，如此循环50次，试写出代码。

程序:

#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
pthread_mutex_t mutex;
pthread_cond_t cond;
int main_flog = 0;
int sub_flog = 0;
int main_count = 0;
int sub_count = 0;
void *sub_thread_func(void *argv);
void main_thread_func();
int main()
{
pthread_t tid;
int ret;
pthread_mutex_init(&mutex,NULL);
pthread_cond_init(&cond,NULL);
ret = pthread_create(&tid,NULL,sub_thread_func,NULL);
if(ret == -1)
{
perror("pthread_create errpr!\n");
exit(-1);
}
main_thread_func();
ret = pthread_join(tid,NULL);
if(ret == -1)
{
printf("pthread_join error!\n");
exit(-1);
}
return 0;
}
void *sub_thread_func(void *argv)
{
int i;
while(1)
{
sub_count++;
for(i = 1; i <= 3; i++)
{
printf("sub pthread%d:%d\n",sub_count,i);
}
while(1)
{
pthread_mutex_lock(&mutex);
if(main_flog == 1)
{
pthread_cond_signal(&cond);
pthread_mutex_unlock(&mutex);
break;
}
pthread_mutex_unlock(&mutex);
}
pthread_mutex_lock(&mutex);
sub_flog = 1;
pthread_cond_wait(&cond,&mutex);
sub_flog = 0;
pthread_mutex_unlock(&mutex);
//sub_count++;
if(sub_count >= 50)
{
printf("sub_pthread loop 50 times!\n");
break;
}
}
return (void *)0;
}
void main_thread_func(void)
{
int i;
while(1)
{
main_count++;
pthread_mutex_lock(&mutex);
main_flog = 1;
pthread_cond_wait(&cond,&mutex);
main_flog = 0;
pthread_mutex_unlock(&mutex);
for(i = 1; i <= 6; i++)
{
printf("main phread%d:%d\n",main_count,i);
}
while(1)
{
pthread_mutex_lock(&mutex);
if(sub_flog == 1)
{
pthread_cond_signal(&cond);
pthread_mutex_unlock(&mutex);
break;
}
pthread_mutex_unlock(&mutex);
}
//main_count++;
if(main_count >= 50)
{
printf("main_phread loop 50 times!\n");
break;
}
}
}

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