1.拷贝文件

2.信号量

#include "head.h"
sem_t sem1,sem2;
void* inter_a(void* arg)
{
	while(1)
	{   
		sleep(1);
		printf("A\n");
		sem_post(&sem1);
}
pthread_exit(NULL);
}
void* inter_b(void* arg)
{
	while(1)
	{
		sem_wait(&sem1);
		printf("B\n");
		sem_post(&sem2);
	}
	pthread_exit(NULL);
}
void* inter_c(void* arg)
{   
	
	while(1)
	{  
		sem_wait(&sem2);
		printf("C\n");
	}
	pthread_exit(NULL);
}
int main(int argc, const char *argv[])
{
	sem_init(&sem1,0,0);
    sem_init(&sem2,0,0);
	pthread_t tid1,tid2,tid3;
	if((errno=pthread_create(&tid1,NULL,inter_a,NULL))!=0)
		PRINT_ERROR("create error");
	if((errno=pthread_create(&tid2,NULL,inter_b,NULL))!=0)
		PRINT_ERROR("create error");
	if((errno=pthread_create(&tid3,NULL,inter_c,NULL))!=0)
		PRINT_ERROR("create error");
	pthread_join(tid1,NULL);
	pthread_join(tid2,NULL);
	pthread_join(tid3,NULL);
	sem_destroy(&sem1);
	sem_destroy(&sem2);
	return 0;
}

条件变量

#include "head.h"
pthread_cond_t cond;
pthread_cond_t cond2;
pthread_cond_t cond3;
//pthread_cond_t cond=PTHREAD_COND_INITIALIZER;
pthread_mutex_t mutex;
int flag=0;
void* inter_a(void* arg)
{   while(1)
	{ 
	pthread_mutex_lock(&mutex);
	if(flag==1)
		pthread_cond_wait(&cond,&mutex);
	flag=1;
	printf("A\n");
	pthread_cond_signal(&cond2);
	pthread_mutex_unlock(&mutex);
	}
	pthread_exit(NULL);
}
void* inter_b(void* arg)
{
	while(1)
	{  
		pthread_mutex_lock(&mutex);
		if(flag==0)
		pthread_cond_wait(&cond2,&mutex);
		//唤醒后又上了一次锁，所以后面要再一次解锁
		flag=0;
		printf("B\n");
		pthread_mutex_unlock(&mutex);
		pthread_cond_signal(&cond3);
	}
	pthread_exit(NULL);
}
void* inter_c(void* arg)
{
    while(1)
    {
        pthread_mutex_lock(&mutex);
        if(flag==2)
        pthread_cond_wait(&cond3,&mutex);
        //唤醒后又上了一次锁，所以后面要再一次解锁
        flag=2;
        printf("C\n");
        pthread_mutex_unlock(&mutex);
		pthread_cond_signal(&cond);
    }
    pthread_exit(NULL);
}

int main(int argc, const char *argv[])
{
	pthread_cond_init(&cond,NULL);
	pthread_cond_init(&cond2,NULL);
	pthread_cond_init(&cond3,NULL);
	pthread_t rid,rid2,rid3;
	if((errno=pthread_create(&rid,NULL,inter_a,NULL)!=0))
		PRINT_ERROR("create error");
	if((errno=pthread_create(&rid2,NULL,inter_b,NULL)!=0))
		PRINT_ERROR("create error");
	if((errno=pthread_create(&rid3,NULL,inter_c,NULL)!=0))
		PRINT_ERROR("create error");
 	pthread_join(rid,NULL);
 	pthread_join(rid2,NULL);
 	pthread_join(rid3,NULL);
 	pthread_cond_destroy(&cond);
	pthread_cond_destroy(&cond2);
	pthread_cond_destroy(&cond3);
	return 0;
}