C#计算当前日期是一年中的第几周

方法一：

 

private   int   WeekOfYear(string   date)
{
DateTime   curDay   =   Convert.ToDateTime(date);

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

int   days   =   curDay.DayOfYear;
int   daysOutOneWeek   =   days   -   (7   -   firstdayofweek);

if   (daysOutOneWeek   <=   0)
{
return   1;
}
else
{
int   weeks   =   daysOutOneWeek   /   7;
if   (daysOutOneWeek   %   7   !=   0)
weeks   ++;

return   weeks   +   1;
}
}

方法二：

 

System.Globalization.GregorianCalendar   gc   =   new   System.Globalization.GregorianCalendar();
int   weekOfYear   =   gc.GetWeekOfYear(DateTime.Now,   System.Globalization.CalendarWeekRule.FirstDay,   DayOfWeek.Monday);