C#根据当前日期的周几计算上周日期的区间（按中国习惯周一是第一天）

int week = (int)DateTime.Now.DayOfWeek;//获取当前日期为周几
week = (week == 0) ? 7 : week;//如果（week==0）为ture,week=7，否则week=week;
DateTime upMon = DateTime.Now.AddDays(1 - week - 7);//上周一
DateTime upSun = DateTime.Now.AddDays(-week);//上周日

出处  ：https://blog.csdn.net/u012408847/article/details/80599204