$re = '/^www\.example\.(?:com|co(?:\.(?:in|uk))?|net|us|me)\/([^\/\n]+)\/([^\/\n]+)$/m';
$str = 'www.example.com
www.example.com/
www.example.com/example1
www.example.net/example1/
www.example.co.uk/example1/something
www.example.co.in/example1/something/';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($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