$re = '/^(?<operator>eq|ne|gt|lt|ge|le|ct|bt):(?<firstValue>-?[0-9]+)(-(?<secondValue>-?[0-9]+))?$/m';
$str = 'eq:54
bt:52-56
lt:-1';
preg_match_all($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