regularni vyraz a nepovinne udaje v retezci

$data = '
<a href="http://www.example.com" title="title1">Test1</a>
<a href="http://www.example.com" title="title2">Test2</a>
<a href="http://www.example.com" title="">Test3</a>
<a href="http://www.example.com">Test4</a>
<a href="http://www.example.com" target="_blank">Test5</a>
';

preg_match_all('~<a href=\"http://www.example.com\" title=\"(.*)\" target=\"(.*)\">(.*)</a>~', $data, $match);

print_r($match);