$re = '/<string>(.*?)<\/string>/';
$str = '<map>
<entry>
<string>id</string>
<string>555</string>
</entry>
<entry>
<string>label</string>
<string>Need This Value</string>
</entry>
<entry>
<string>key</string>
<string>748</string>
</entry>
</map>';
preg_match_all($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