$re = '/-(?P<percent>\d+,\d+)% vanaf (?P<amount>\d+) (?P<unit>\w+), vanaf (?P<start_date>\d{2}/\d{2}/\d{4}) tot en met (?P<end_date>\d{2}/\d{2}/\d{4})/';
$str = '-20,00% vanaf 2 st, vanaf 26/07/2017 tot en met 08/08/2017';
preg_match_all($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