Question

我正在寻找一些逻辑，以便在给定日期的同一天（例如：星期三）和同一周（例如：第一或第二......）的N个月后获得日期。

ex：12-06-2013（6月的周三和第3周）是给定日期。在这里，我将在给定日期增加3个月。结果应该是2013年8月14日（星期三和8月的第3周）。

如果您需要更多说明，请告诉我。

提前致谢。

Answer 1

好的，所以我个人使用我的Noda Time库来做到这一点。使用DateTime完全可以做到这一点，但我个人觉得更难。当然，我也鼓励您使用Noda Time作为更好的日期/时间API。所以我有类似的东西：

static LocalDate AddMonthsPreserveWeekDayAndWeek(LocalDate start, int months)
{
    // This isn't the week of month in the "normal" sense; it's the nth
    // occurrence of this weekday.
    int week = ((start.DayOfMonth - 1) / 7) + 1;

    // This will usually give the same day of month, but truncating where
    // necessary
    LocalDate monthsAdded = start.AddMonths(months);
    LocalDate endOfPreviousMonth = monthsAdded.AddDays(-monthsAdded.Day);

    // Get to the first occurrence of the right day-of-week
    LocalDate firstRightDay = endOfPreviousMonth.Next(start.IsoDayOfWeek);

    // Usually this will be right - but it might overflow to the next month,
    // in which case we can just rewind by a week.
    LocalDate candidate = firstRightDay.PlusWeeks(week - 1);
    return candidate.Month == firstRightDay.Month ? candidate
                                                  : candidate.PlusWeeks(-1);
}

这是完全未经测试的 - 你应该绝对有一堆单元测试（理想情况下，你甚至可以在编写这些代码之前编写）测试你感兴趣的各种边缘情况。< / p>

Answer 2

使用标准MDSN年= 2013月= 06日= 12

1）从特定日期（星期日为0）获取星期几

DateTime dateValue = new DateTime(year, month, date);  
Console.WriteLine((int) dateValue.DayOfWeek);      // Displays 3 implying it is Wed

2）从特定日期获取该月的一周

DayofWeek = 3 (from previous calculation)
Day = 12 
EndOfWeek = Day + (6 - DayOfWeek) = 12 + 4 = 16  
NoWeek = 0
while (EndOfWeek > 0)
{
   EndOfWeek  -= 7;
   NoWeek++;        
}

=＆GT; NoWeek = 3

3）在N个月后获得第一个日期

DateTime newDate = new DateTime(year, month, 1)

newDate.AddMonths(N); // Let it be 2 => August 1, 2013

4）获取新日期的星期几

newDay = newDate.DayOfWeek  // Return 4 implying Thursday

5）获取NoWeek之后的最后一天

newDate.AddDays(6-newDay) => newDate.AddDays (6-4) => August 3,2013
NoWeek--;
while (NoWeek > 1)
{
    newDate.AddDays(7);
    NoWeek--;
}

=＆GT; newDate将是Augus 10,2013

6） Calculte required date

newDate.AddDays(DayofWeek) =>newDate will be August 14,2013

如何在给定日期的同一天和同一周的N个月之后获得日期

2 个答案: