C#（C sharp）字串和時間的相互轉換。

一、DateTime –> string

時間型別轉化成字串型別，那是相當的簡單，直接呼叫ToString()方法即可。如：

DateTime dt = DateTime.Now;

string dtStr = dt.ToString();

如果想對輸出格式化，可以這麼寫：

dt.ToString("yyyy年MM月dd日");//2005年11月5日
dt.ToString("yyyy-MM-dd");//2005-11-5

string.Format("{0:d}",dt);//2005-11-5
string.Format("{0:D}",dt);//2005年11月5日

時間型別格式化（成字元型別）可以通過兩種方式：1、自定義時間格式。自己定義時間的構成和表示；2、標準時間格式。由標準庫提供的有限的表示方式。（詳細的情參考列表）

二、string -> DateTime

string dtString = “2009-10-12 00:12:05”;

DateTime dt = DateTime.Parse(dtStr); //方式一

DateTime dt2 = Convert.ToDateTime(dtStr);//方式二

當然DateTime也有多種表示方式（非格式化成字串型別），如：

dt.ToFileTimeUtc();//127756704859912816
dt.ToLocalTime();//2005-11-5 21:21:25
dt.ToLongDateString();//2005

當然如果最後要打印出來，就需要ToString()一下，轉化成字串型別。

三、時間的其它方法，屬性和運算

dt.Year //2005 dt.Date //2005-11-5 0:00:00 dt.DayOfWeek //Saturday dt.DayOfYear //309 dt.Hour //13 dt.Millisecond //441 dt.Minute //30 dt.Month //11 dt.Second //28 dt.Ticks //632667942284412864 dt.TimeOfDay //13:30:28.4412864 dt //2005-11-5 13:47:04 運算： dt.AddYears(1) //2006-11-5 13:47:04 dt.AddDays(1.1) //2005-11-6 16:11:04 dt.AddHours(1.1) //2005-11-5 14:53:04 dt.AddMilliseconds(1.1) //2005-11-5 13:47:04 dt.AddMonths(1) //2005-12-5 13:47:04 dt.AddSeconds(1.1) //2005-11-5 13:47:05 dt.AddMinutes(1.1) //2005-11-5 13:48:10 dt.AddTicks(1000) //2005-11-5 13:47:04 dt.CompareTo(dt) //0 dt.Equals("2005-11-6 16:11:04") //False dt.Equals(dt) //True dt.GetHashCode() //1474088234 dt.GetType() //System.DateTime dt.GetTypeCode() //DateTime

參考：

Custom DateTime Formatting

There are following custom format specifiers y (year), M (month), d (day), h (hour 12), H (hour 24), m (minute), s (second), f (second fraction), F (second fraction, trailing zeroes are trimmed), t (P.M or A.M) and z (time zone).

Following examples demonstrate how are the format specifiers rewritten to the output.

// create date time 2008-03-09 16:05:07.123 DateTime dt = new DateTime(2008, 3, 9, 16, 5, 7, 123); String.Format("{0:y yy yyy yyyy}", dt); // "8 08 008 2008" year String.Format("{0:M MM MMM MMMM}", dt); // "3 03 Mar March" month String.Format("{0:d dd ddd dddd}", dt); // "9 09 Sun Sunday" day String.Format("{0:h hh H HH}", dt); // "4 04 16 16" hour 12/24 String.Format("{0:m mm}", dt); // "5 05" minute String.Format("{0:s ss}", dt); // "7 07" second String.Format("{0:f ff fff ffff}", dt); // "1 12 123 1230" sec.fraction String.Format("{0:F FF FFF FFFF}", dt); // "1 12 123 123" without zeroes String.Format("{0:t tt}", dt); // "P PM" A.M. or P.M. String.Format("{0:z zz zzz}", dt); // "-6 -06 -06:00" time zone

You can use also date separator / (slash) and time sepatator :

// date separator in german culture is "." (so "/" changes to ".") String.Format("{0:d/M/yyyy HH:mm:ss}", dt); // "9/3/2008 16:05:07" - english (en-US) String.Format("{0:d/M/yyyy HH:mm:ss}", dt); // "9.3.2008 16:05:07" - german (de-DE)

Here are some examples of custom date and time formatting:

[C#]

// month/day numbers without/with leading zeroes String.Format("{0:M/d/yyyy}", dt); // "3/9/2008" String.Format("{0:MM/dd/yyyy}", dt); // "03/09/2008" // day/month names String.Format("{0:ddd, MMM d, yyyy}", dt); // "Sun, Mar 9, 2008" String.Format("{0:dddd, MMMM d, yyyy}", dt); // "Sunday, March 9, 2008" // two/four digit year String.Format("{0:MM/dd/yy}", dt); // "03/09/08" String.Format("{0:MM/dd/yyyy}", dt); // "03/09/2008"

Standard DateTime Formatting

In DateTimeForma­tInfo there are defined standard patterns for the current culture. For example property ShortTimePattern is string that contains value h:mm tt for en-US culture and value HH:mm for de-DE culture.

Following table shows patterns defined in DateTimeForma­tInfo and their values for en-US culture. First column contains format specifiers for the String.Format method.

Following examples show usage of standard format specifiers in String.Format method and the resulting output.

在C#中用於DateTime -> string的轉化

String.Format("{0:t}", dt); // "4:05 PM" ShortTime String.Format("{0:d}", dt); // "3/9/2008" ShortDate String.Format("{0:T}", dt); // "4:05:07 PM" LongTime String.Format("{0:D}", dt); // "Sunday, March 09, 2008" LongDate String.Format("{0:f}", dt); // "Sunday, March 09, 2008 4:05 PM" LongDate+ShortTime String.Format("{0:F}", dt); // "Sunday, March 09, 2008 4:05:07 PM" FullDateTime String.Format("{0:g}", dt); // "3/9/2008 4:05 PM" ShortDate+ShortTime String.Format("{0:G}", dt); // "3/9/2008 4:05:07 PM" ShortDate+LongTime String.Format("{0:m}", dt); // "March 09" MonthDay String.Format("{0:y}", dt); // "March, 2008" YearMonth String.Format("{0:r}", dt); // "Sun, 09 Mar 2008 16:05:07 GMT" RFC1123 String.Format("{0:s}", dt); // "2008-03-09T16:05:07" SortableDateTime String.Format("{0:u}", dt); // "2008-03-09 16:05:07Z" UniversalSortableDateTime

See also