{C#}Datetime 找出本周星期幾日期

//當天本周的周五日期
var nowFriWeek = DateTime.Now.AddDays(Convert.ToDouble((0 - Convert.ToInt16(DateTime.Now.DayOfWeek)) + 5));


DateTime.Now.DayOfWeek---今天為星期幾
Convert.ToInt16(DateTime.Now.DayOfWeek)---如為0，則為本周周日，以此類推
(0 - Convert.ToInt16(DateTime.Now.DayOfWeek))--要加幾天算出本周周日(本周第一天)



參考資料：
http://tw.myblog.yahoo.com/terence-lee/article?mid=164