C#计算当前是第几周System.Globalization.GregorianCalendar

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自己计算时，有时特殊边界值 没有考虑到 会触发bug。用这个系统自带的比较靠谱

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

自己定义参考算法：

  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;
  　}
　}