#include <pthread.h>
#include <sys/types.h>
#include <linux/sem.h>
#include <stdio.h>int semID; //semID/*P操作*/
void P(int semid,int index)
{
struct sembuf sem;
sem.sem_num = index;
sem.sem_op = -1;
sem.sem_flg = 0;
semop(semid,&sem,1);
return;
}/*V操作*/
void V(int semid,int index)
{
struct sembuf sem;
sem.sem_num = index;
sem.sem_op = 1;
sem.sem_flg = 0;
semop(semid,&sem,1);
return;
}int a=0;/*线程1，负责计算*/
void *subp1()
{//负责将1加到100
int i =1;
for(;i<=100;i++)
{
P(semID,0);
printf("Thread 1 is adding!\n");
a += i;
V(semID,1);
}
return;
}/*负责打印中间结果*/
void *subp2()
{
int i;
for( i=1;i<=100;i++){
//打印出内容
P(semID,1);
printf("Thread 2 is printing:");
printf("%d\n",a);
V(semID,0);
}
return 0;
}int main()
{
key_t key =1;
/*创建信号灯:2个*/
semID = semget(key,2,IPC_CREAT | 0666);//信号灯赋初值1
union semun arg1,arg2;
arg1.val = 1;
arg2.val = 0;semctl(semID,0,SETVAL,arg1);
semctl(semID,1,SETVAL,arg2);//创建两个线程p1和P2
pthread_t p1,p2;
int get1,get2;
get1 = pthread_create(&p1,NULL,(void*)subp1,NULL);
get2 = pthread_create(&p2,NULL,(void*)subp2,NULL);//等待两个线程运行结束
pthread_join(p1,NULL);
pthread_join(p2,NULL);//删除信号灯
int isDelete;
isDelete = semctl(semID,1,IPC_RMID,arg1);
}