进行折扣和合同重量后计算正确的金额

Question

我在 .net core 控制台应用程序中有这段代码：-

var currentDate = startdate;

while (currentDate <= enddate)
{
    // Get the days in the current month
    var daysInMonth = DateTime.DaysInMonth(currentDate.Year, currentDate.Month);

    // Calculate the number of days within the current month
    var monthStart = currentDate;
    var monthEnd = new DateTime(currentDate.Year, currentDate.Month, daysInMonth);
    if (monthEnd > enddate) monthEnd = enddate;

    var daysInCurrentMonth = Convert.ToDecimal(Math.Truncate((monthEnd - monthStart).TotalDays + 1));

    // Proportion of the amount for this month
    var monthlyAmount = decimal.Parse((daysInCurrentMonth / totalDays).ToString()) * Amount;

    // Apply discount if applicable
    monthlyAmount = Math.Round((Discount != null ? monthlyAmount * (1 - (Decimal.Parse(Discount.ToString()) / 100)) : monthlyAmount),3);

    // Add to the result list
    monthlyAmounts.Add(

       (ContractType,
        monthStart,
        monthEnd,
        monthStart.Month.ToString(),
        monthStart.Year,
        monthlyAmount,
        NetworkID,
        NetworkTitle,
        MediumTitle,
        (MediumID != null ? MediumID.ToString() : null),
        BookingCalendarID,
        BookingCalendarIDSalesRepIDMap
            .SingleOrDefault(a => a.Key == BookingCalendarID).Value, daysInCurrentMonth, totalDays, monthlyAmount)
    );

    // Move to the next month
    currentDate = monthEnd.AddDays(1);
}

金额货币为 JOD，最多保留 3 位小数。

我的问题是关于这两行代码：-

var monthlyAmount = decimal.Parse((daysInCurrentMonth / totalDays).ToString()) * Amount;
    
// Apply discount if applicable
monthlyAmount = Math.Round((Discount != null ? monthlyAmount * (1 - (Decimal.Parse(Discount.ToString()) / 100)) : monthlyAmount),3);

那么我的计算正确吗？例如，我有一份从

22/10/2024

开始到

4/11/2024

的合同，金额为 1000 JOD（有 3 位小数），折扣为 15%。所以当我想计算11月份的合同金额时，它将如下：-

每月金额 = 4/14 * 1,000 = 285.7142857142857

每月金额 = Math.Round(285.7142857142857 * 0.85,3) = 242.857 JOD

另外，当我计算 10 月份时，我会得到

607.142

.. 但是当我求和 242.857 + 607.142 = 849.999 .. 时，会损失 0.001 JOD .. 那么我该如何解决这个问题？

谢谢

Answer 1

我只是将代码放入 vs 中，并删除了所有转换并在双精度类型的基础上计算了所有内容。经过计算，我得到了所需的 850 JOD。

这是我使用的代码（必须添加一些变量来执行）：

DateTime startdate = new DateTime(2024,10,22);
DateTime enddate = new DateTime(2024,11,4);
List<double> monthlyAmounts = new List<double>();
double Discount = 15.0d;
double Amount = 1000.0d;

var currentDate = startdate;
double totalDays = enddate.Subtract(startdate).TotalDays+1;

while (currentDate <= enddate)
{
// Get the days in the current month
var daysInMonth = DateTime.DaysInMonth(currentDate.Year, currentDate.Month);

// Calculate the number of days within the current month
var monthStart = currentDate;
var monthEnd = new DateTime(currentDate.Year, currentDate.Month, daysInMonth);
if (monthEnd > enddate) monthEnd = enddate;

var daysInCurrentMonth = Math.Truncate((monthEnd - monthStart).TotalDays + 1);

// Proportion of the amount for this month
var monthlyAmount = (daysInCurrentMonth / totalDays) * Amount;

// Apply discount if applicable
monthlyAmount = Math.Round((Discount != null ? monthlyAmount * (1 - (Discount / 100)) : monthlyAmount), 3);

// Add to the result list
monthlyAmounts.Add(monthlyAmount);

// Move to the next month
currentDate = monthEnd.AddDays(1);
}

我假设所有类型转换在计算过程中可能会损失一点精度。如果您知道必须使用十进制数字，请尝试将所有必需的整数也以十进制为基础以避免转换损失:)