日期属于一年中的第几周

public int GetWeekthOfTime(DateTime dt)

{

int firstdayofweek = Convert.ToInt32(Convert.ToDateTime(dt.Year.ToString() + "-" + "1-1 ").DayOfWeek);

int days = dt.DayOfYear;

int daysOutOneWeek = days - (7 - firstdayofweek);

if (daysOutOneWeek <= 0)

{

return 1;

}

else

{

int weeks = daysOutOneWeek / 7;

if (daysOutOneWeek % 7 != 0)

weeks++;

if (dt.DayOfWeek == DayOfWeek.Sunday) weeks--;

return weeks + 1;

}

}