php-ip-addr-math.php

<?php
/*
     Given an IP address and Subnet Mask,
     determine the subnet address, broadcast address, and wildcard mask
     by using bitwise operators

     ref:  http://php.net/manual/en/language.operators.bitwise.php
*/

$ip='10.10.10.7';
$mask='255.255.255.0';
$wcmask=long2ip( ~ip2long($mask) );
$subnet=long2ip( ip2long($ip) & ip2long($mask) );
$bcast=long2ip( ip2long($ip) | ip2long($wcmask) );
echo "Given address $ip and mask $mask, \n" .
"the subnet is $subnet and broadcast is $bcast \n" .
"with a wildcard mask of $wcmask";

/*
Given address 10.10.10.7 and mask 255.255.255.0,
the subnet is 10.10.10.0 and broadcast is 10.10.10.255
with a wildcard mask of 0.0.0.255
*/

?>