信号量的例子(無順序)

信号量的例子

//gcc -lpthread *.c -o 

#include <stdio.h>
#include <pthread.h>
#include <sys/types.h>
#include <semaphore.h>
#include <unistd.h>

int number;
sem_t sem_id;

void *thread_one_fun(void *arg)
{
	sem_wait(&sem_id);
	printf("thread one have the semaphore\n");
	number++;
	printf("number  =%d\n",number);
	sem_post(&sem_id);
}
void *thread_two_fun(void *arg)
{
	sem_wait(&sem_id);
	printf("thread two have the semaphore\n");
	number--;
	printf("number=%d\n",number);
	sem_post(&sem_id);
}

int main(int argc,char *argv[])
{
	number = 1;
	pthread_t id1,id2;
	sem_init(&sem_id,0,1);
	pthread_create(&id1,NULL,thread_one_fun,NULL);
	pthread_create(&id2,NULL,thread_two_fun,NULL);
	pthread_join(id1,NULL);
	pthread_join(id2,NULL);
	printf("Main...\n");
	return 0;
}