C# x 日期變化

//改變日期format

string startStr = start.ToString("yyyy-MM-dd HH:mm:ss");

DateTime dt = Convert.ToDateTime(startStr);//轉回DateTime

P.S format 大小寫意義不同: MM=month, mm=Minutes, HH=24hours, hh=12hours

//日期時間相加減

DateTime start = Convert.ToDateTime("2011-04-25 15:50:39");

DateTime end = Convert.ToDateTime("2011-05-02 15:50:39");

TimeSpan ts = end.subtract(start); //兩時間天數相減

double dayCount = ts.Days; //相距天數

//目前時間

DateTime dt = DateTime.Now;

//本周周一

DateTime startWeek = dt.AddDays(1 - Convert.ToInt32(dt.DayOfWeek.ToString("d")));

//本周周日

DateTime endWeek = startWeek.AddDays(6);

//本月月初

DateTime startMonth = dt.AddDays(1 - dt.Day);

//本月月末

DateTime endMonth = startMonth.AddMonths(1).AddDays(-1);



參考資料 : http://bluemuta38.pixnet.net/blog/post/61533149-%E5%90%84%E7%A8%AE%E6%97%A5%E6%9C%9F%E6%99%82%E9%96%93%E8%A8%88%E7%AE%97