C#获得当前日期是一年中的第几周

利用 System.Globalization.GregorianCalendar 获得指定时间是当前年份的第几周

System.Globalization.GregorianCalendar gc = new System.Globalization.GregorianCalendar();
int WeekIndex = gc.GetWeekOfYear(time, System.Globalization.CalendarWeekRule.FirstFullWeek, DayOfWeek.Sunday);