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expr5.c
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expr5.c
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//
// Created by zcw on 11/21/19.
//
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ipc.h>
#include <sys/msg.h>
#include <sys/wait.h>
struct message {
char m[20];
}msg;
int main() {
pid_t sender, receiver;
int qid;
int e;
qid = msgget(88, IPC_CREAT | 0666);
if (qid == -1) {
perror("Failed in calling msgget");
return -1;
}
while (1) {
sender = fork();
if (sender == 0) {
char a[20];
printf("In sender: ");
scanf("%s", a);
if (strcmp(a, "exit") == 0) {
exit(1);
}
strcpy(msg.m, a);
msgsnd(qid, &msg, 20, 0);
exit(0);
}
else if (sender < 0) {
printf("Fork error");
exit(1);
}
else {
wait(&e);
if (WEXITSTATUS(e) == 1){
msgctl(qid, IPC_RMID, 0);
exit(0);
}
receiver = fork();
if (receiver == 0) {
msgrcv(qid, &msg, 20, 0, 0);
printf("In receiver: ");
printf("%s\n", msg.m);
exit(0);
}
else if (receiver < 0) {
printf("Fork error");
exit(1);
}
else {
wait(NULL);
}
}
}
}