知道第几周，如何计算该周包括哪几天？

Question

如题。比如，2012年第10周，如何求该周是从    几月几号 到 几月几号？

Answer 1

//某日期加10天的日期
dt.AddDays(10)
其值為這個執行個體所表示日期和時間加上 value 所表示天數的總和。//某天是星期几
dt.DayOfWeek 
表示一週天數。這個屬性值的範圍從 0 開始 (表示星期日) 到 6 (表示星期六)。

Answer 2

给你写了个完整的例子
int weekNumber = 10;
            int daynumber = (weekNumber - 1) * 7;            string target = "2012/01/01";
            DateTime day = Convert.ToDateTime(target);
            string week = day.DayOfWeek.ToString();
            //TimeSpan span = new TimeSpan(daynumber, 0, 0, 0);
            day = day.AddDays(daynumber);
            string Newdate = day.DayOfWeek.ToString();
            //lbl_week.Text = Newdate;            DateTime startDate = new DateTime();
            DateTime endDate = new DateTime();
            switch (Newdate)
            {
                case "Monday":
                    {
                        TimeSpan spanDed = new TimeSpan(0, 0, 0, 0);
                        TimeSpan spanAdd = new TimeSpan(6, 0, 0, 0);
                        startDate = day.Add(spanDed);
                        endDate = day.Add(spanAdd);
                        break;
                    }
                case "Tuesday":
                    {
                        TimeSpan spanDed = new TimeSpan(-1, 0, 0, 0);
                        TimeSpan spanAdd = new TimeSpan(5, 0, 0, 0);
                        startDate = day.Add(spanDed);
                        endDate = day.Add(spanAdd);
                        break;
                    }
                case "Wednesday":
                    {
                        TimeSpan spanDed = new TimeSpan(-2, 0, 0, 0);
                        TimeSpan spanAdd = new TimeSpan(4, 0, 0, 0);
                        startDate = day.Add(spanDed);
                        endDate = day.Add(spanAdd);
                        break;
                    }
                case "Thursday":
                    {
                        TimeSpan spanDed = new TimeSpan(-3, 0, 0, 0);
                        TimeSpan spanAdd = new TimeSpan(3, 0, 0, 0);
                        startDate = day.Add(spanDed);
                        endDate = day.Add(spanAdd);
                        break;
                    }
                case "Friday":
                    {
                        TimeSpan spanDed = new TimeSpan(-4, 0, 0, 0);
                        TimeSpan spanAdd = new TimeSpan(2, 0, 0, 0);
                        startDate = day.Add(spanDed);
                        endDate = day.Add(spanAdd);
                        break;
                    }
                case "Saturday":
                    {
                        TimeSpan spanDed = new TimeSpan(-5, 0, 0, 0);
                        TimeSpan spanAdd = new TimeSpan(1, 0, 0, 0);
                        startDate = day.Add(spanDed);
                        endDate = day.Add(spanAdd);
                        break;
                    }
                case "Sunday":
                    {
                        TimeSpan spanDed = new TimeSpan(-6, 0, 0, 0);
                        TimeSpan spanAdd = new TimeSpan(0, 0, 0, 0);
                        startDate = day.Add(spanDed);
                        endDate = day.Add(spanAdd);
                        break;
                    }            }
            lbl_start.Text = startDate.ToShortDateString();
            lbl_end.Text = endDate.ToShortDateString();