note 80642 added to function.ip2long

A common way to express IP addresses and subnet masks is to use what is refered to as slash notation. Instead of writing out: IP = 192.168.100.2 Subnet Mask = 255.255.240.0 Writing out "192.168.100.2/20" is much shorter. If you are looking for a way to convert a subnet mask into it's slash notation counterpart, here is a single line of code that can perform this task. $slash_notation = strlen(preg_replace("/0/", "", decbin(ip2long($subnet_mask)))); For example... A subnet mask of 255.255.240.0 expressed in binary looks like this: 11111111111111111111000000000000 This gives us a slash notation of 20 which is simply counting the number of 1's in the masks binary representation. Here is a function that uses this code to return an IP address and subnet mask in slash notation. function slash_notation($ip, $mask) { return $ip."/".strlen(preg_replace("/0/", "", decbin(ip2long($mask)))); } calling slash_notation("192.168.100.2", "255.255.255.0"); will return "192.168.100.2/24". Hope this is of use to some of you out there. ---- Server IP: 209.41.74.194 Probable Submitter: 66.190.12.156 ---- Manual Page -- http://www.php.net/manual/en/function.ip2long.php Edit -- https://master.php.net/note/edit/80642 Del: integrated -- https://master.php.net/note/delete/80642/integrated Del: useless -- https://master.php.net/note/delete/80642/useless Del: bad code -- https://master.php.net/note/delete/80642/bad+code Del: spam -- https://master.php.net/note/delete/80642/spam Del: non-english -- https://master.php.net/note/delete/80642/non-english Del: in docs -- https://master.php.net/note/delete/80642/in+docs Del: other reasons-- https://master.php.net/note/delete/80642 Reject -- https://master.php.net/note/reject/80642 Search -- https://master.php.net/manage/user-notes.php