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源代码：

receive.c

#include <stdio.h>

#include <stdlib.h>

#include <unistd.h>

#include <sys/ipc.h>

#include <sys/types.h>

#include <sys/sem.h>

int main()

{

int semid,semval1,semval2;

key_t key;

key=ftok(“./tt”,1);

semid=semget(key,2,IPC_CREAT|0666);

int val;

printf(“等待接收—-\n”);

while(1)

{

semval1=semctl(semid,0,GETVAL,0);

semval2=semctl(semid,1,GETVAL,1);

if(semval1==semval2)

{

printf(“信号量1==信号量2\n”);

printf(“hello\n”);

break;

}

}

return 0;

}

send.c

#include <stdio.h>

#include <stdlib.h>

#include <sys/types.h>

#include <sys/ipc.h>

#include <sys/sem.h>

#include <unistd.h>

int main(int argc,char const *argv[])

{

int semid;

key_t key;

key=ftok(“./tt”,1);

semid=semget(key,2,IPC_CREAT|0666);

if(semid<0)

{

printf(“semget error\n”);

exit(1);

}

typedef union semnu{

int value;

struct semid_ds *buf;

unsigned short int *array;

struct seminfo *nbuf;

}sem;

sem sem0,sem1;

sem0.value=1;

sem1.value=3;

semctl(semid,0,SETVAL,sem0);

semctl(semid,1,SETVAL,sem1);

semctl(semid,0,GETVAL);

semctl(semid,1,GETVAL);

struct sembuf buf_p[2];

buf_p[0].sem_num = 0;

buf_p[0].sem_op =1;

buf_p[0].sem_flg = (IPC_NOWAIT|SEM_UNDO);

buf_p[1].sem_num = 1;

buf_p[1].sem_op = -1;

buf_p[1].sem_flg = (IPC_NOWAIT|SEM_UNDO);

int i=1;

while(1){

int val0,val1;

val0=semctl(semid,0,GETVAL);

val1=semctl(semid,1,GETVAL);

printf(“第%d次\n”,i);

i++;

printf(“信号量1=%d  信号量2= %d\n\n”,val0,val1);

if(val0==val1)

{

printf(“信号量1==信号量2——结束退出\n”);

break;

}

sleep(3);

semop(semid,buf_p,2);

}

return 0;

}