“半月”要加多少天?

本文关键字：多少 半月 | 更新日期: 2023-09-27 18:17:51

我有一个名为PaymentFrequency的枚举类型，其值表示每年支付的金额…这里是

public enum PaymentFrequency
{
    None             = 0,
    Annually         = 1,
    SemiAnnually     = 2,
    EveryFourthMonth = 3,
    Quarterly        = 4,
    BiMonthly        = 6,
    Monthly          = 12,
    EveryFourthWeek  = 13,
    SemiMonthly      = 24,
    BiWeekly         = 26,
    Weekly           = 52
}

基于NumberOfPayments, PaymentFrequency和FirstPaymentDate(类型为DateTimeOffset)，我想计算LastPaymentDate。但我有问题，弄清楚有多少时间单位(天，月)的情况下添加半月…

    switch (paymentFrequency)
    {
        // add years...
        case PaymentFrequency.Annually:
            LastPaymentDate = FirstPaymentDate.AddYears(NumberOfPayments - 1); 
            break;
        // add months...
        case PaymentFrequency.SemiAnnually:
            LastPaymentDate = FirstPaymentDate.AddMonths((NumberOfPayments - 1) * 6); // 6 months
            break;
        case PaymentFrequency.EveryFourthMonth:
            LastPaymentDate = FirstPaymentDate.AddMonths((NumberOfPayments - 1) * 4); // 4 months
            break;
        case PaymentFrequency.Quarterly:
            LastPaymentDate = FirstPaymentDate.AddMonths((NumberOfPayments - 1) * 3); // 3 months
            break;
        case PaymentFrequency.BiMonthly:
            LastPaymentDate = FirstPaymentDate.AddMonths((NumberOfPayments - 1) * 2); // 2 months
            break;
        case PaymentFrequency.Monthly:
            LastPaymentDate = FirstPaymentDate.AddMonths(NumberOfPayments - 1);
            break;
        // add days...
        case PaymentFrequency.EveryFourthWeek:
            LastPaymentDate = FirstPaymentDate.AddDays((NumberOfPayments - 1) * 4 * 7); // 4 weeks (1 week = 7 days)
            break;
        case PaymentFrequency.SemiMonthly:
            // NOTE: how many days in semi month? AddMonths (0.5) does not work :)
            LastPaymentDate = FirstPaymentDate.AddMonths((NumberOfPayments - 1) * 0.5); // 2 weeks (1 week = 7 days)
            break;
        case PaymentFrequency.BiWeekly:
            LastPaymentDate = FirstPaymentDate.AddDays((NumberOfPayments - 1) * 2 * 7); // 2 weeks (1 week = 7 days)
            break;
        case PaymentFrequency.Weekly:
            LastPaymentDate = FirstPaymentDate.AddDays((NumberOfPayments - 1) * 7); // 1 week (1 week = 7 days)
            break;
        case PaymentFrequency.None:
        default:
            throw new ArgumentException("Payment frequency is not initialized to valid value!", "paymentFrequency");
    }

那么，当使用semimonmonth时，我应该使用多少天/月?如果不知道每个月之间确切的天数，这有可能吗?或者这真的很简单，我刚刚用完咖啡因，我看不到森林的树木:)

“半月”要加多少天?

对于半月制，如果你的第一次付款总是每月的第一次付款(也就是说，从1号到13号的任何时间，13号之后开始是有问题的，正如评论中讨论的那样)，你可以这样做:

 // assuming first payment will be 1st of month, add month for every 2 payments
 // num payments / 2 (int division, remainder is chucked)
 // then add 15 days if this is even payment of the month
 LastPaymentDate = FirstPaymentDate.AddMonths((NumberOfPayments - 1) / 2)
     .AddDays((NumberOfPayments % 2) == 0 ? 15 : 0);

对于第一次付款，这将增加0个月零0天，所以是第一次付款日期。对于第二次付款，这将增加0个月(分割，其余部分被丢弃)和15天的16个月。对于第三次付款，这将增加1个月(1/3)，下个月1日将增加0天，等等。

这里假设FirstPaymentDate在某个给定月的1号。如果你想让16日成为开始日期，你可能会看到从这里开始的地方，等等。

有意义吗?

为了说明，如果我们有:

DateTime LastPaymentDate, FirstPaymentDate = new DateTime(2011, 12, 5);
for(int numOfPayments=1; numOfPayments<=24; numOfPayments++)
{
    LastPaymentDate = FirstPaymentDate.AddMonths((numOfPayments - 1) / 2)
        .AddDays((numOfPayments % 2) == 0 ? 15 : 0);
    Console.WriteLine(LastPaymentDate);
}

这个循环会给我们:

12/5/2011 12:00:00 AM
12/20/2011 12:00:00 AM
1/5/2012 12:00:00 AM
// etc...
10/20/2012 12:00:00 AM
11/5/2012 12:00:00 AM
11/20/2012 12:00:00 AM

因为月份有不同的长度，所以不能只添加一个预定义的数字。你必须知道你要处理的是哪个月，然后从那里开始。

如果你知道一个月的1号和16号是到期日，那么最后一次付款是12月16日(假设你计算的是日历年)

半月付款的基本对是:

  • 1日和16日(每月1日和16日)
  • 15 and (2|3)?(每月15日及最后一天)

选择

我最近遇到了同样的问题，但是我需要允许任何日期输入。它有点乱，需要重构，但这是我目前想到的。二月有一些问题，我必须破解。

Date returnDate;
if (numberOfPayments % 2 == 0)
{
   returnDate = date.AddMonths(numberOfPayments / 2);
    if (date.Day == DateTime.DaysInMonth(date.Year, date.Month))//Last day of the month adjustment
    {
        returnDate = new Date(returnDate.Year, returnDate.Month, DateTime.DaysInMonth(returnDate.Year, returnDate.Month));
    }
}
else
{
    returnDate = date.Day <= 15 ? date.AddDays(15).AddMonths((numberOfPayments - 1) / 2) : date.AddDays(-15).AddMonths((numberOfPayments + 1) / 2);
    if (date.Day == DateTime.DaysInMonth(date.Year, date.Month))//Last day of the month adjustment
    {
        returnDate = new Date(returnDate.Year, returnDate.Month, 15);
    }
    else if (date.Month == 2 && date.Day == 14)
    {
        returnDate = returnDate.AddMonths(-1);
        returnDate = new Date(returnDate.Year, returnDate.Month, returnDate.Month == 2 ? 28 : 29);
    }
    else if (date.Month == 2 && date.Day == 15)
    {
        returnDate = returnDate.AddMonths(-1);
        returnDate = new Date(returnDate.Year, returnDateMonth, DateTime.DaysInMonth(returnDate.Year, returnDate.Month));
    }
}
return returnDate;
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