PHP socket_bind error (only one usage of socket address) - php

Question

Below is a PHP script that I have created to listen for incoming messages (XML strings).
That PHP script is hosted on my local home server on port 13330 so that's where I would listen for incoming requests, right? So I create the socket and bind it to the address the file is located on.
I receive this error: Warning: socket_bind(): unable to bind address [0]: Only one usage of each socket address (protocol/network address/port) is normally permitted.
I would appreciate it if anyone could let me know why I might be seeing that.
Thanks
createSocketServer();
function createSocketServer() {
// Set time limit to indefinite execution
set_time_limit (0);
// Set the ip and port we will listen on
$address = '127.0.0.1';
$port = 13330;
// Create a TCP Stream socket
$sock = socket_create(AF_INET, SOCK_STREAM, 0);
echo '<p>Socket created</p>';
// Bind the socket to an address/port
socket_bind($sock, $address, $port) or die('Could not bind to address');
echo '<p>Socket binded</p>';
// Start listening for connections
socket_listen($sock);
echo '<p>Socket listening</p>';
/* Accept incoming requests and handle them as child processes */
$client = socket_accept($sock);
// Read the input from the client – 1024 bytes
$input = socket_read($client, 1024);
// Strip all white spaces from input
$output = ereg_replace("[ \t\n\r]","",$input).chr(0);
echo $output;
}

Answer 1

use this code before binding:
if (!socket_set_option($socket, SOL_SOCKET, SO_REUSEADDR, 1)) {
echo socket_strerror(socket_last_error($socket));
exit;
}
for reference http://www.php.net/manual/en/function.socket-bind.php
You can also check http://www.php.net/manual/en/function.socket-set-option.php for details