I am newbie with regex and I want to use preg_match
function to find if a string is an IP address.
For example,
$string = "10.0.0.1";
preg_match($regex, $string);
should return true. So, what $regex
should be?
Don't use a regex when you don't need to :)
$valid = filter_var($string, FILTER_VALIDATE_IP);
Though if you really do want a regex...
$valid = preg_match('/^\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}\z/', $string);
The regex however will only validate the format, the max for any octet is the max for an unsigned byte, or 255
.
This is why IPv6 is necessary - an IPv4 address is only 32bits long and the internet is popular :)