$re = '/(?\'type\'A|B|C)-(?:(?\'diameter\'\d+)x(?\'length\'\d+)|(?\'length\'\d+))/mJ';
$str = 'A-5
B-6x3
C-79
A-99x1';
preg_match_all($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