$re = '/ZB[^,]*(?=,?)/';
$str = 'ZP-S,ZB-MA-S,ZB,ZB-MA-M,ZB-MA-B,ZP,PY,ZB-ME-S,ZB-ME-M,PY,ZB-ME-B,PY-S,PY-M,PY-B,ZP-B,ZB-MA-S-LS-MLE-PES';
preg_match_all($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