$re = '/\/(blogs?|lofiversion|archives?|boards?|groups?|discussions?|forums?|threads?|show(post|thread|topic)|view(thread|topic)|(index\.php))/';
$str = 'http://www.hydrogenaud.io/forums/lofiversion/index.php/t48386.html';
preg_match($re, $str, $matches, PREG_OFFSET_CAPTURE, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php