[转]求当天为所在的周是第几周

   按每周第一天是星期天来算

//当年第一天

DateTime fisrtDayOfYear = Convert.ToDateTime(DateTime.Now.Year.ToString() + "/" + "01/01");

Response.Write("当年的第一天："+fisrtDayOfYear+"
");

//当年第一天是星期几

string firstWeekDayOfYear = fisrtDayOfYear.DayOfWeek.ToString();

Response.Write("当年第一天是星期几："+firstWeekDayOfYear+"
");

int i;

switch (firstWeekDayOfYear)

       {

        

            case "Monday":

                i = 6;

            break;

            case "Tuesday":

                i = 5;

            break;

            case "Wednesday":

                i = 4;

            break;

            case "Thursday":

                i = 3;

            break;

            case "Friday":

                i = 2;

            break;

            case "Saturday":

                i = 1;

            break;

            default:

                i = 7;

            break;

           

        }

 

  //当天为第几天

  int currentDayOfYear = DateTime.Now.DayOfYear;

  Response.Write("当天是当年的第几天：" + currentDayOfYear.ToString() + "
");

  int currentWeekOfYear = (currentDayOfYear - i) / 7;

  if (currentWeekOfYear <= 0)

      currentWeekOfYear +=1;

  else

      currentWeekOfYear += 2;

  Response.Write("当天是第" + currentWeekOfYear + "周
");

  int currentWeekDay = (currentDayOfYear - i) % 7;

  Response.Write("当天是星期" + (currentWeekDay-1));