using  System.Globalization;

///   <summary> 
///  获取某一日期是该年中的第几周
///   </summary> 
///   <param name="dt"> 日期 </param> 
///   <returns> 该日期在该年中的周数 </returns> 
private   int  GetWeekOfYear(DateTime dt)
{
    GregorianCalendar gc  =   new  GregorianCalendar();
     return  gc.GetWeekOfYear(dt, CalendarWeekRule.FirstDay, DayOfWeek.Monday);
}

///   <summary> 
///  获取某一年有多少周
///   </summary> 
///   <param name="year"> 年份 </param> 
///   <returns> 该年周数 </returns> 
private   int  GetWeekAmount( int  year)
{
    DateTime end  =   new  DateTime(year,  12 ,  31 );   // 该年最后一天 
    System.Globalization.GregorianCalendar gc  =   new  GregorianCalendar();
     return  gc.GetWeekOfYear(end, CalendarWeekRule.FirstDay, DayOfWeek.Monday);   // 该年星期数 
}