시스템 프로그래밍 관련해서 질문 좀 할게요..

int main(void)
{
        int fd;
        struct namecard card;
        char buf[MAXLEN];
        int i;
 
        fd = open("mynamecard", O_RDONLY, 0644);
        if (fd == -1)
        {
                printf("Error: cannot open\n");
                exit(1);
        }
 
        do 
        {
             printf("\n");
             printf("Enter i: ");
             gets(buf);
             i = atoi(buf);
             lseek(fd, i*sizeof(struct namecard), SEEK_SET);
             read(fd, &card, sizeof(struct namecard));
             printf("Name: %s\n", card.name);
             printf("phone number: %s\n", card.phone);
 
             printf("Continue (y/n)? ");
             gets(buf);
        } while (!strcmp(buf,"y") || !strcmp(buf,"Y"));
 
        close(fd);
}