$re = '/<(tag*)>(.*?)<\/\1>\./';
$str = '<p><tag>Lorem</tag>. Excepteur sint.</p>
<p><tag>Lorem.</tag> Excepteur sint.</p>
<p><tag>Lorem ipsum</tag>. Excepteur sint.</p>
<p><tag>Lorem ipsum.</tag> Excepteur sint.</p>
<p><tag>Lorem ipsum Excepteur</tag>. Sint.</p>
<p><tag>Lorem ipsum Excepteur</tag>. Sint.</p>
';
preg_match($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