$re = '/(<first>|<last>|<state>)/mi';
$str = '<first>Micky</first>
<last>Mouse</last>
<state>CA</state>
<first>Donald</first>
<LAST>Duck</LAST>
<state>FL</state>
<FIRST>Gyro</FIRST>
<last>Gearloose</last>
<state>MA</state>';
preg_match_all($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