计算从当前日期开始的最后 16 个星期四 [关闭]

Question

我有 c# asp.net 应用程序。 我想计算前 16 个 Thursday 的日期，同时给出当前日期，它会给出 16 个最后一个 Thursday's 的日期。

请为此提供示例代码。

非常感谢。

Answer 1

此方法有效：

public static IList<DateTime> GetWeekDays(DateTime startDate, DayOfWeek day, int count, bool pastDays, bool includeStartDate)
{
    int start = (int)startDate.DayOfWeek;
    int desired = (int)day;
    int offset;
    int diff = Math.Abs(start - desired);
    if(!includeStartDate && start == desired)
        diff = 7;
    offset = pastDays ? (-1) * (7- diff) : diff;
    int weekDays = pastDays ? (-1) * 7 : 7;
    DateTime firstDay = startDate.AddDays(offset);
    IList<DateTime> dates = Enumerable.Range(0, count)
        .Select(i => firstDay.AddDays(i * weekDays))
        .ToList();
    return dates;
}

它支持两个方向。

用法很简单：

IList<DateTime> past16Wednesdays = GetWeekDays(DateTime.Today, DayOfWeek.Wednesday, 16, true, true);
foreach(DateTime dt in past16Wednesdays)
    Console.WriteLine(dt.ToString("d", CultureInfo.InvariantCulture));

结果是

11/20/2013
11/13/2013
11/06/2013
10/30/2013
10/23/2013
10/16/2013
10/09/2013
10/02/2013
09/25/2013
09/18/2013
09/11/2013
09/04/2013
08/28/2013
08/21/2013
08/14/2013
08/07/2013