int socket_fd;
socket_fd = socket(AF_INET, SOCK_STREAM, 0);
if (socket_fd == -1) {
    printf("could not create socket\n");
    return 1;
}

struct sockaddr_in server;
server.sin_addr.s_addr = inet_addr(addr);
server.sin_family = AF_INET;
server.sin_port = htons(atoi(port));

if (connect(socket_fd, (struct sockaddr*) &server, sizeof(server)) < 0) {
    printf("connect error\n");
    return 1;
}

char buff[100];
memset(buff, '\0', sizeof(buff));
sprintf(buff, "cs230 HELLO %s\n", netid);
printf("%s", buff);
send(socket_fd, buff, strlen(buff), 0);

while (true) {
    memset(buff, '\0', sizeof(buff));
    recv(socket_fd, buff, sizeof(buff), 0);
    printf("%s", buff);

    // ... do some stuff/send back the result

}