Kein DateDiff in PHP

  function DateDiff($Interval, $s, $t = NULL) {
    if ($t == NULL) $t = time();

    switch ($Interval) {
      case "s": return $t - $s;
      case "M": return intval(($t - $s) / 60);
      case "h": return intval(($t - $s) / 3600);
      case "d": return intval(
                  (ISP_Date_BeginOfDay($t) - ISP_Date_BeginOfDay($s)
                ) / 3600 / 24);
      case "m":
        $sMonth = intval(date("m", $s));
        $lMonth = intval(date("m", $t));
        $sYear = intval(date("Y", $s));
        $lYear = intval(date("Y", $t));

        return ($lYear - $sYear) * 12 + ($lMonth - $sMonth);
      case "y": return intval(date("Y", $t)) - intval(date("Y", $s));
    }
  }