How to convert URLs to LINKs?

 
    function url_to_link($s){
        $find = '((?:https?://|ftp://|www\.)[\w.-]+[^\s<>]+)';
        $link = "<a href=\"$0\" rel=\"nofollow\" target=\"_blank\">$0</a>";
        return preg_replace($find, $link, $s);
    }