在比较两个日期时，我如何使用DateTimePicker来说明月份的变化？

Question

我正试图使用windows窗体和C#创建一个基本的酒店房间预订应用程序。我最初是通过创建for循环开始的，理由是到达日期总是小于离开日期。这一切都如预期的那样工作，直到我试着为6月30日预订一个房间，并在7月1日离开。从下面的代码可以看出，它永远不会进入for-loop，因为到达日期不<比出发日期小。我创建了一个maxDays int，其中包含了这个人将要停留的最大天数，并将其作为循环的锚。这可能归结为大部分逻辑问题和一些愚蠢的错误，因为我在代码中几乎没有使用日期的经验。任何关于这个问题的建议都将是巨大的。

private void CalculateButton_Click(object sender, EventArgs e)
    {
        //Prints out number of nights at hotel.
        NumberOfNightsTextbox.Text = (DepartureDatePicker.Value.Day - ArrivalDatePicker.Value.Day).ToString("d");

        //Creates a copy of the current Arrival and Departure date.
        DateTimePicker ArrivalCopy = ArrivalDatePicker;
        DateTimePicker DepartureCopy = DepartureDatePicker;

        //Creates an int to store the current Arrival and Departure Month.
        int arrivalMonth = ArrivalDatePicker.Value.Month;
        int departureMonth = DepartureDatePicker.Value.Month;

        //Creates a int that is used to determine how many loops the For statement should loop for.
        //May need to add the monthly days after doing a check.
        int maxDays = DepartureDatePicker.Value.Day;

        //Gets the difference of the Arrival and Departure and converts it to an Int.
        double differnceD = (DepartureDatePicker.Value - ArrivalDatePicker.Value).TotalDays;
        int diff = (int)Math.Round(differnceD);

        if (arrivalMonth < departureMonth)
        {
            if (departureMonth == 1 || departureMonth == 3 ||
                departureMonth == 5 || departureMonth == 7 ||
                departureMonth == 8 || departureMonth == 10 ||
                departureMonth == 11)
            {
                diff += 31;

            }
            else if (departureMonth == 2)
            {
                diff += 28;

            }
            else if (departureMonth == 4 || departureMonth == 6 || departureMonth == 9 || departureMonth == 11)
            {
                diff += 30;

            }
        }
        if (arrivalMonth == departureMonth)
        {
            for (int i = ArrivalDatePicker.Value.Day; i < maxDays + 1; i++)
            {
                if (ArrivalCopy.Value.DayOfWeek == DayOfWeek.Saturday || ArrivalCopy.Value.DayOfWeek == DayOfWeek.Sunday)
                {
                    increasePriceNight++;
                }

                ArrivalCopy.Value = ArrivalCopy.Value.AddDays(1);
            }
        }

        TotalPriceTextbox.Text = (((diff - increasePriceNight) * 120) + (increasePriceNight * 150)).ToString("C");

        AvgPricePerNightTextbox.Text = ((((diff - increasePriceNight) * 120) + (increasePriceNight * 150)) / diff).ToString();
    }

Answer 1

你有总的天数，该人将留在那里。你可以使用AddDays方法来查看某一天是周六还是周日。例如

 for ( int i = 0; i <= maxDays; i++ )
        {
            DateTime date = ArrivalCopy.Value.AddDays( i );

            if ( date.DayOfWeek == DayOfWeek.Saturday || date.DayOfWeek == DayOfWeek.Sunday )
            {
                increasePriceNight++;
            }
        }

Answer 2

我不知道你为什么决定用这种逻辑。你可以做得更简单

double days = (DepartureDatePicker.Value - ArrivalDatePicker.Value).TotalDays;
int daysTotal = Convert.ToInt32(Math.Ceiling(days));

基本上，如果原 days 是类似0.2或1.3的东西，你只需将其四舍五入到下一个整数。这就是人必须支付的天数。

现在，有了天数，你可以迭代你的 dates每次重复增加一天，并检查是哪一天，并收取适当的费用 - 折扣或加价

DateTeime startDate = ArrivalDatePicker.Value.Date;
decimal totalPrice = 0;
for (int dayNo = 0; dayNo < daysTotal;  dayNo++)
{
    DateTime currDate = startDate.AddDays(dayNo);
    totalPrice += GetPriceForDate(currDate);
}

在 GetPriceForDate 你调查一下日期。周几、月几号等，并根据业务规则进行定价。