C#（C sharp）字符串和时间的相互转换

C#（C sharp）字符串和时间的相互转换。

 

一、DateTime –> string

时间类型转化成字符串类型，那是相当的简单，直接调用ToString()方法即可。如：

DateTime dt = DateTime.Now;

string dtStr = dt.ToString();

 

如果想对输出格式化，可以这么写：

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

 

时间类型格式化（成字符类型）可以通过两种方式：1、自定义时间格式。自己定义时间的构成和表示；2、标准时间格式。由标准库提供的有限的表示方式。（详细的情参考列表）

 

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

 

当然DateTime也有多种表示方式（非格式化成字符串类型），如：

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

 

当然如果最后要打印出来，就需要ToString()一下，转化成字符串类型。

 

三、时间的其它方法，属性和运算

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 运算： 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   

参考：

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 : (colon). These characters will be rewritten to characters defined in the current DateTimeForma­tInfo.DateSepa­rator and DateTimeForma­tInfo.TimeSepa­rator.

// 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.

Specifier	DateTimeFormatInfo property	Pattern value (for en-US culture)
t	ShortTimePattern	h:mm tt
d	ShortDatePattern	M/d/yyyy
T	LongTimePattern	h:mm:ss tt
D	LongDatePattern	dddd, MMMM dd, yyyy
f	(combination of D and t)	dddd, MMMM dd, yyyy h:mm tt
F	FullDateTimePattern	dddd, MMMM dd, yyyy h:mm:ss tt
g	(combination of d and t)	M/d/yyyy h:mm tt
G	(combination of d and T)	M/d/yyyy h:mm:ss tt
m, M	MonthDayPattern	MMMM dd
y, Y	YearMonthPattern	MMMM, yyyy
r, R	RFC1123Pattern	ddd, dd MMM yyyy HH':'mm':'ss 'GMT' (*)
s	SortableDateTi­mePattern	yyyy'-'MM'-'dd'T'HH':'mm':'ss (*)
u	UniversalSorta­bleDateTimePat­tern	yyyy'-'MM'-'dd HH':'mm':'ss'Z' (*)
		(*) = culture independent

 

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

 

在C#中用于DateTime -> string的转化

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

1. [C#] String Format for Double – format float numbers
2. [C#] String Format for Int – format (align) integer numbers
3. [C#] IFormatProvider for Numbers – parse float numbers with IFormatProvider
4. [C#] Custom IFormatProvider – string formatting with custom IFormatProvider
5. [C#] Align String with Spaces – how to align text to the right or left
6. [C#] Indent String with Spaces – how to indent text with repeated spaces
7. Custom Date and Time Format Strings – MSDN – custom date-time formatting
8. Standard Date and Time Format Strings – MSDN – standard date-time formatting
9. DateTimeForma­tInfo – MSDN – date-time patterns for specific cultures
10. String.Format – MSDN – method to format strings