$re = '/(http[s]?:\/\/|\w+(?=\.)|\.\w+)/';
$str = 'http://www.mail.yahoo.co.uk/blah/blah
https://test.test.again.mail.yahoo.com/blah/blah';
preg_match_all($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