创建三个线程,分别打印 a,b,c.

创建三个线程,分别打印 a,b,c. 现在要求用信号量对线程进行同步，无论程序运行多少次、如何运行，都能使整个程序依次打印 a b c a b c a b c . . . 一直死循环

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<assert.h>
#include<unistd.h>

#include<pthread.h>
#include<sys/sem.h>
#include<semaphore.h>

#define MAX 3
sem_t sem1;
sem_t sem2;
sem_t sem3;
void *fun1(void *arg)
{
   while(1)
   {
       sem_wait(&sem1);
       printf("a\n");
       sem_post(&sem2);
   }
}

void *fun2(void *arg)
{
   while(1)
   {
       sem_wait(&sem2);
       printf("b\n");
       sem_post(&sem3);
   }
}
void *fun3(void *arg)
{
   while(1)
   {
       sem_wait(&sem3);
       printf("c\n");
       sem_post(&sem1);
   }
}
int main()
{
   pthread_t id[MAX];
   pthread_create(&id[0],NULL,fun1,NULL);
   pthread_create(&id[1],NULL,fun2,NULL);
   pthread_create(&id[2],NULL,fun3,NULL);
   sem_init(&sem1,0,1);
   sem_init(&sem2,0,0);
   sem_init(&sem3,0,0);
   int i = 0;
   for (;i < MAX;i++)
   {
       pthread_join(id[i],NULL);
   }
   sem_destroy(&sem1);
   sem_destroy(&sem2);
   sem_destroy(&sem3);
   exit(0);
}

结果如下:

创建三个线程,分别打印 a,b,c.