Client implementation for POSIX client-server program

posix_client.cpp

#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/shm.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <time.h>

#define SIZE     2

char getRand() {
    int num = (rand() % 9) + 49;
    return num;
}

int main() {
    int shmid;
    key_t key;
    char *shm, *s;

    key = 5678;

    shmid = shmget(key, SIZE, 0666);
    shm = shmat(shmid, NULL, 0);

    srand(time(NULL));

    while (1) {
        sleep(1);
        puts("server:");
        puts(shm);
        if (*shm == '7') {
            exit(0);
        } else {
            s = shm;
            *s = getRand();
            *s++;
            *s = NULL;
        }
        puts("client:");
        puts(shm);
    }

    exit(0);
}