shared memory 관련 질문입니다~~

int output(int a, struct in_data *dt)
{
        int i;
        int shmid;
        key_t key = 0x00000001;
        char *memory;
        char buf[1024];
 
        shmid = shmget(key, SIZE_DATA, IPC_CREAT|0666);
        memory = (char*)shmat(shmid, 0, 0);
        dt = (struct in_data*)memory;
 
        for(i=0; i<a; i++) {
                if(a==0) {
                        printf("ÀúÀå½ÇÆÐ!!\n");
                        break;
                }
                else
                        sprintf(buf, "%s, %d, %s, %s\n", dt[i].name, dt[i].age, dt[i].sex, dt[i].res);
                        // printf("%s", buf);
                        strcpy(memory, buf);
        }
                        printf("%s", buf);
                        printf("%s", memory);
 
        return 0;
}