方法二：
System.Globalization.GregorianCalendar gc = new System.Globalization.GregorianCalendar();
int weekOfYear = gc.GetWeekOfYear(DateTime.Now, System.Globalization.CalendarWeekRule.FirstDay, DayOfWeek.Monday);
week_num.GetWeekOfYear(New DateTime(Convert.ToInt32(arr_md(2)),Convert.ToInt32(arr_md(0)),Convert.ToInt32(arr_md(1))),System.Globalization.CalendarWeekRule.FirstDay, DayOfWeek.Monday)
New DateTime(Convert.ToInt32(arr_md(2)),Convert.ToInt32(arr_md(0)),Convert.ToInt32(arr_md(1))) 需要写成 New DateTime(2020,08,09) 算的这天是 今年的多少周
