SELECT()

this is used to wait for an event on one or more sockets

    // 10. select() - Wait for an event on the socket
    fd_set readfds;
    FD_ZERO(&readfds);
    FD_SET(client_socket, &readfds);
    struct timeval timeout = {5, 0}; // 5 seconds timeout
    if (select(client_socket + 1, &readfds, NULL, NULL, &timeout) < 0) {
        perror("select");
    } else if (FD_ISSET(client_socket, &readfds)) {
        printf("Data is available to read.\n");
    }