獲得當年的周別

#region Get week name in year
  public string GetWeekName(string dd)   //得到當前日期本周的名字
  {
   int FirstSaturday=0;
   string t1 = Convert.ToDateTime(dd).Year.ToString()+"/1/1";
   DateTime dt1 = Convert.ToDateTime(t1);
   for(int i=0;i<7;i++)
   {
    if(dt1.AddDays(i).DayOfWeek.ToString()=="Saturday")
    {
     FirstSaturday = i+1;
     break;
    }
   }

   int m1 = Convert.ToDateTime(dd).DayOfYear;
   int w1 = (m1-FirstSaturday-1)/7;
   int a;
   string A="";
   if(m1<=FirstSaturday)
   {
    a=1;
   }
   else if(m1<=FirstSaturday+7)
   {
    a=2;
   }
   else
   {
    a = w1+2;
   }

   if(a!=1)
   {
    if(a<10)
    {
     A="0"+a.ToString();
     return "W"+A;
    }
    else
    {
     return "W"+a.ToString();
    }  
   }
   else
   {
    string tt = dt1.AddDays(-1).ToShortDateString();
    if(dt1.Year>Convert.ToDateTime(tt).Year)
    {
     if(a<10)
     {
      return "W"+"0"+a.ToString();
     }
     else
     {
      return "W"+a.ToString();
     }
     
    }
    else
    {
     return GetWeekName(tt);
    }
   }
  }
  #endregion