Regular expression - URL validator

Hello, I found this regular expression on a web site. It is basicaly an URL validator. I'm trying to implement this in my web site, but i receive errors. I think this is a PERL REGEX so what should i do to make it work in php? $valid = (preg_match('^((((H|h)(T|t)|(F|f))(T|t)(P|p)((S|s)?))\://)?(www.|[a-zA-Z0-9] .)[a-zA-Z0-9\-\.]+\.[a-zA-Z]{2,6}(\:[0-9]{1,5})*(/($|[a-zA-Z0-9\.\,\;\?\'\\\ +&%\$#\=~_\-]+))*$', $_POST['website'])); if ($valido == 0) { something here; } else { something else here; } Thanks a lot in advance, Wagner.