$re = '/(seventeen|thirteen|fourteen|eighteen|nineteen|thousand|fifteen|sixteen|seventy|hundred|eleven|twelve|twenty|thirty|fourty|eighty|ninety|three|seven|eight|forty|fifty|sixty|four|five|nine|one|two|six|ten)/i';
$str = 'twothousandninehundredfiftyeight';
preg_match_all($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