$re = '/(<input\sclass="InputfieldFileSort")/';
$str = '<input class="InputfieldFileSort" type="text" name="sort_carousel_images_13cf00760bff00f05d6a3a3b2c40a1e7" value="0">';
preg_match($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