C#获取指定日期为一年中的第几周

 /// <summary>
 /// 获取指定日期，在为一年中为第几周
 /// </summary>
 /// <param name="dt">指定时间</param>
 /// <reutrn>返回第几周</reutrn>
 private static int GetWeekOfYear(DateTime dt)
 {
 　　GregorianCalendar gc = new GregorianCalendar();
 　　int weekOfYear = gc.GetWeekOfYear(dt,CalendarWeekRule.FirstDay, DayOfWeek.Monday);
 　　return weekOfYear;
 }