php时间运算

    public function getLotteryInfo()
    {
      $endTime = $this->getEndTime();

      $dateStr = $endTime->format('Y-m-d');
      $partOneStartTime = new Datetime(date("$dateStr 00:00:00"));
      $partTwoStartTime = new Datetime(date("$dateStr 02:00:00"));
      $partThreeStartTime = new Datetime(date("$dateStr 10:00:00"));
      $partFourStartTime = new Datetime(date("$dateStr 22:00:00"));
      $partFiveStartTime = new Datetime(date("$dateStr 23:59:59"));

      $startTime = new Datetime(date('Y-m-d 00:00:00'));
      {
         $interval = $endTime->diff($partOneStartTime);
         $number = $interval->h * 12 + (int)($interval->i/5) + 1;
      }
$preAppendedNumber = sprintf("%0"."3d", $number);
      return $dateStr = $endTime->format('n月j日').'第'.$preAppendedNumber.'期';
    }