.net如何根据年月算出这个月有几个周，分别是几号到几号

Question

.net如何根据年月算出这个月有几个周，分别是几号到几号,意思是
第一个周 （几号——几号）
第二个周 （几号——几号）
......
希望高手给我一个方法 谢谢

Answer 1

--本月的第一个星期一   
  select   DATEADD(wk,   
  DATEDIFF(wk,0,dateadd(dd,6-datepart(day,getdate()),getdate())),   0)

Answer 2

using System;namespace ConsoleApplication1
{
    internal class Program
    {
        private static void Main()
        {
            DateTime day = new DateTime(DateTime.Now.Year, DateTime.Now.Month, 1);
            DateTime lastDay = new DateTime(DateTime.Now.Year, DateTime.Now.Month + 1, 1).AddDays(-1);
            int i = 0;
            do
            {
                Console.WriteLine("Week {0}:", ++i);
                while (day.DayOfWeek != DayOfWeek.Sunday && day <= lastDay)
                {
                    Console.WriteLine("\t{0} is {1}", day.ToShortDateString(), day.DayOfWeek);
                    day = day.AddDays(1);
                }
                if (day <= lastDay)
                {
                    Console.WriteLine("\t{0} is {1}", day.ToShortDateString(), day.DayOfWeek);
                    day = day.AddDays(1);
                }
            } while (day <= lastDay);            Console.ReadLine();
        }
    }
}

Answer 3

没有什么常理，要看你的规则int year = Convert.ToInt32(textBox1.Text);
int month = Convert.ToInt32(textBox2.Text);
DateTime weekStart = new DateTime(year, month, 1);
DateTime monEnd = weekStart.AddMonths(1).AddDays(-1);
int i = 1;
int dayOfWeek = Convert.ToInt32(weekStart.DayOfWeek.ToString("d"));
DateTime weekEnd = dayOfWeek == 0 ? weekStart : weekStart.AddDays(7 - dayOfWeek);  //该月第一周结束日期
richTextBox2.Text += "第" + i + "周起始日期： " + weekStart.ToShortDateString() + "   结束日期： " + weekEnd.ToShortDateString() + "\n";
while (weekEnd.AddDays(1) < monEnd)
{
    i++;
    weekStart = weekEnd.AddDays(1);
    weekEnd = weekEnd.AddDays(7) > monEnd ? monEnd : weekEnd.AddDays(7);
    richTextBox2.Text += "第" + i + "周起始日期： " + weekStart.ToShortDateString() + "   结束日期： " + weekEnd.ToShortDateString() + "\n";
}
richTextBox2.Text += year + "年" + month + "月共有" + i + "周\n";其实就是AddDays和AddMonths的组合，简单的写了下，懒得做优化了，或者参考C#根据当前时间确定日期范围（本周、本月、本季度、本年度） 

Answer 4

        private void ShowWeekSinMonth(int y, int m)
        {
            int days = DateTime.DaysInMonth(y, m);
            int weeks =1;
            DateTime FirstDayOfMonth = DateTime.Parse(y + "-" + m + "-1");            DateTime FirstDayOfWeek = FirstDayOfMonth;
            while (FirstDayOfWeek.Month  == m)
            {
                Response.Write("第" + weeks + "周：");
                Response.Write(FirstDayOfWeek.ToString("yyyy年MM月dd日"));
                Response.Write("--");
                DateTime LastDayOfWeek;
                if (FirstDayOfWeek.Day + 7 > days)
                {
                    LastDayOfWeek = FirstDayOfWeek.AddDays(days - FirstDayOfWeek.Day);
                }
                else
                {
                    LastDayOfWeek = FirstDayOfWeek.AddDays(7 - getWeekDay(FirstDayOfWeek) -1);
                }
                Response.Write(LastDayOfWeek.ToString("yyyy年MM月dd日"));
                Response.Write("<BR>");
                weeks += 1;
                FirstDayOfWeek = LastDayOfWeek.AddDays(1);
            }
        }
        private int getWeekDay(DateTime d)
        { 
            return (d.Day+2*d.Month+3*(d.Month+1)/5+d.Year+d.Year/4-d.Year/100+d.Year/400 + 1) % 7;
        }

Answer 5

[code=BatchFile]第1周：2009年05月01日--2009年05月02日
第2周：2009年05月03日--2009年05月09日
第3周：2009年05月10日--2009年05月16日
第4周：2009年05月17日--2009年05月23日
第5周：2009年05月24日--2009年05月30日
第6周：2009年05月31日--2009年05月31日[/code]

Answer 6

http://www.lhdwy.com.cn/aspnet/20090404/0904041101255487.html

Answer 7

            if (year % 4 == 0 && year % 100 != 0)
            { 
                _mDay[1] = 29;
            }
            else if (year % 400 == 0)
            {
                _mDay[1] = 29;
            }            //total week of the month
            int sum;
            DateTime[,] weekArray;
            
            DateTime dt = new DateTime(year, month, 1);
            
            if (dt.DayOfWeek != DayOfWeek.Sunday)
            {
                int _week = (int)dt.DayOfWeek;                //how many day this week last
                int _day = 6 - _week;                //how many day this month last
                int lastDay = _mDay[month - 1] - (_day + 1);                if (lastDay / 7 == 0) 
                { 
                    sum = (lastDay / 7) + 1; 
                }                 else
                {
                    sum = (lastDay / 7) + 2;
                }
                weekArray = new DateTime[sum, 2];
                weekArray[0, 0] = dt;
                weekArray[0, 1] = dt.AddDays(_day);                for (int i = 1; i < sum; i++)
                {
                    weekArray[i, 0] = weekArray[i - 1, 1].AddDays(1);
                    weekArray[i, 1] = weekArray[i - 1, 1].AddDays(7);
                }            }
            else
            {
                int lastDay = _mDay[month - 1];                if (lastDay / 7 == 0)
                {
                    sum = (lastDay / 7); 
                }
                else 
                {
                    sum = (lastDay / 7) + 1;
                }                weekArray = new DateTime[sum, 2];
                weekArray[0, 0] = dt;
                weekArray[0, 1] = dt.AddDays(6);                for (int i = 1; i < sum; i++)
                {
                    weekArray[i, 0] = weekArray[i - 1, 1].AddDays(1);
                    weekArray[i, 1] = weekArray[i - 1, 1].AddDays(7);
                }
            }
            BeginDate = weekArray[week - 1, 0];
            EndDate = weekArray[week - 1, 1];

Answer 8

datepart(week,getdate())只是取得是本年的第几周,如果是本月的第几周,用:   
    
  select   datepart(week,getdate())-datepart(week,getdate()-day(getdate()))+1