How can I visualize the way various DateTime forma

问题:

I want to be able to quickly reference how various DateTime formats will appear, rather than embark upon a laborious process of edit, compile, gawk, and recurse until satisfied.

回答1:

This shows all the formats for the current culture:

StringBuilder sb = new StringBuilder();
foreach (string dateTimePattern in DateTimeFormatInfo.CurrentInfo.GetAllDateTimePatterns()) {
    sb.AppendFormat("{0} = {1}\r\n", dateTimePattern, DateTime.Now.ToString(dateTimePattern));
}

StringBuilder contents after:

M/d/yyyy = 7/18/2012
M/d/yy = 7/18/12
MM/dd/yy = 07/18/12
MM/dd/yyyy = 07/18/2012
yy/MM/dd = 12/07/18
yyyy-MM-dd = 2012-07-18
dd-MMM-yy = 18-Jul-12
dddd, MMMM dd, yyyy = Wednesday, July 18, 2012
MMMM dd, yyyy = July 18, 2012
dddd, dd MMMM, yyyy = Wednesday, 18 July, 2012
dd MMMM, yyyy = 18 July, 2012
dddd, MMMM dd, yyyy h:mm tt = Wednesday, July 18, 2012 4:25 PM
dddd, MMMM dd, yyyy hh:mm tt = Wednesday, July 18, 2012 04:25 PM
dddd, MMMM dd, yyyy H:mm = Wednesday, July 18, 2012 16:25
dddd, MMMM dd, yyyy HH:mm = Wednesday, July 18, 2012 16:25
MMMM dd, yyyy h:mm tt = July 18, 2012 4:25 PM
MMMM dd, yyyy hh:mm tt = July 18, 2012 04:25 PM
MMMM dd, yyyy H:mm = July 18, 2012 16:25
MMMM dd, yyyy HH:mm = July 18, 2012 16:25
dddd, dd MMMM, yyyy h:mm tt = Wednesday, 18 July, 2012 4:25 PM
dddd, dd MMMM, yyyy hh:mm tt = Wednesday, 18 July, 2012 04:25 PM
dddd, dd MMMM, yyyy H:mm = Wednesday, 18 July, 2012 16:25
dddd, dd MMMM, yyyy HH:mm = Wednesday, 18 July, 2012 16:25
dd MMMM, yyyy h:mm tt = 18 July, 2012 4:25 PM
dd MMMM, yyyy hh:mm tt = 18 July, 2012 04:25 PM
dd MMMM, yyyy H:mm = 18 July, 2012 16:25
dd MMMM, yyyy HH:mm = 18 July, 2012 16:25
dddd, MMMM dd, yyyy h:mm:ss tt = Wednesday, July 18, 2012 4:25:17 PM
dddd, MMMM dd, yyyy hh:mm:ss tt = Wednesday, July 18, 2012 04:25:17 PM
dddd, MMMM dd, yyyy H:mm:ss = Wednesday, July 18, 2012 16:25:17
dddd, MMMM dd, yyyy HH:mm:ss = Wednesday, July 18, 2012 16:25:17
MMMM dd, yyyy h:mm:ss tt = July 18, 2012 4:25:17 PM
MMMM dd, yyyy hh:mm:ss tt = July 18, 2012 04:25:17 PM
MMMM dd, yyyy H:mm:ss = July 18, 2012 16:25:17
MMMM dd, yyyy HH:mm:ss = July 18, 2012 16:25:17
dddd, dd MMMM, yyyy h:mm:ss tt = Wednesday, 18 July, 2012 4:25:17 PM
dddd, dd MMMM, yyyy hh:mm:ss tt = Wednesday, 18 July, 2012 04:25:17 PM
dddd, dd MMMM, yyyy H:mm:ss = Wednesday, 18 July, 2012 16:25:17
dddd, dd MMMM, yyyy HH:mm:ss = Wednesday, 18 July, 2012 16:25:17
dd MMMM, yyyy h:mm:ss tt = 18 July, 2012 4:25:17 PM
dd MMMM, yyyy hh:mm:ss tt = 18 July, 2012 04:25:17 PM
dd MMMM, yyyy H:mm:ss = 18 July, 2012 16:25:17
dd MMMM, yyyy HH:mm:ss = 18 July, 2012 16:25:17
M/d/yyyy h:mm tt = 7/18/2012 4:25 PM
M/d/yyyy hh:mm tt = 7/18/2012 04:25 PM
M/d/yyyy H:mm = 7/18/2012 16:25
M/d/yyyy HH:mm = 7/18/2012 16:25
M/d/yy h:mm tt = 7/18/12 4:25 PM
M/d/yy hh:mm tt = 7/18/12 04:25 PM
M/d/yy H:mm = 7/18/12 16:25
M/d/yy HH:mm = 7/18/12 16:25
MM/dd/yy h:mm tt = 07/18/12 4:25 PM
MM/dd/yy hh:mm tt = 07/18/12 04:25 PM
MM/dd/yy H:mm = 07/18/12 16:25
MM/dd/yy HH:mm = 07/18/12 16:25
MM/dd/yyyy h:mm tt = 07/18/2012 4:25 PM
MM/dd/yyyy hh:mm tt = 07/18/2012 04:25 PM
MM/dd/yyyy H:mm = 07/18/2012 16:25
MM/dd/yyyy HH:mm = 07/18/2012 16:25
yy/MM/dd h:mm tt = 12/07/18 4:25 PM
yy/MM/dd hh:mm tt = 12/07/18 04:25 PM
yy/MM/dd H:mm = 12/07/18 16:25
yy/MM/dd HH:mm = 12/07/18 16:25
yyyy-MM-dd h:mm tt = 2012-07-18 4:25 PM
yyyy-MM-dd hh:mm tt = 2012-07-18 04:25 PM
yyyy-MM-dd H:mm = 2012-07-18 16:25
yyyy-MM-dd HH:mm = 2012-07-18 16:25
dd-MMM-yy h:mm tt = 18-Jul-12 4:25 PM
dd-MMM-yy hh:mm tt = 18-Jul-12 04:25 PM
dd-MMM-yy H:mm = 18-Jul-12 16:25
dd-MMM-yy HH:mm = 18-Jul-12 16:25
M/d/yyyy h:mm:ss tt = 7/18/2012 4:25:17 PM
M/d/yyyy hh:mm:ss tt = 7/18/2012 04:25:17 PM
M/d/yyyy H:mm:ss = 7/18/2012 16:25:17
M/d/yyyy HH:mm:ss = 7/18/2012 16:25:17
M/d/yy h:mm:ss tt = 7/18/12 4:25:17 PM
M/d/yy hh:mm:ss tt = 7/18/12 04:25:17 PM
M/d/yy H:mm:ss = 7/18/12 16:25:17
M/d/yy HH:mm:ss = 7/18/12 16:25:17
MM/dd/yy h:mm:ss tt = 07/18/12 4:25:17 PM
MM/dd/yy hh:mm:ss tt = 07/18/12 04:25:17 PM
MM/dd/yy H:mm:ss = 07/18/12 16:25:17
MM/dd/yy HH:mm:ss = 07/18/12 16:25:17
MM/dd/yyyy h:mm:ss tt = 07/18/2012 4:25:17 PM
MM/dd/yyyy hh:mm:ss tt = 07/18/2012 04:25:17 PM
MM/dd/yyyy H:mm:ss = 07/18/2012 16:25:17
MM/dd/yyyy HH:mm:ss = 07/18/2012 16:25:17
yy/MM/dd h:mm:ss tt = 12/07/18 4:25:17 PM
yy/MM/dd hh:mm:ss tt = 12/07/18 04:25:17 PM
yy/MM/dd H:mm:ss = 12/07/18 16:25:17
yy/MM/dd HH:mm:ss = 12/07/18 16:25:17
yyyy-MM-dd h:mm:ss tt = 2012-07-18 4:25:17 PM
yyyy-MM-dd hh:mm:ss tt = 2012-07-18 04:25:17 PM
yyyy-MM-dd H:mm:ss = 2012-07-18 16:25:17
yyyy-MM-dd HH:mm:ss = 2012-07-18 16:25:17
dd-MMM-yy h:mm:ss tt = 18-Jul-12 4:25:17 PM
dd-MMM-yy hh:mm:ss tt = 18-Jul-12 04:25:17 PM
dd-MMM-yy H:mm:ss = 18-Jul-12 16:25:17
dd-MMM-yy HH:mm:ss = 18-Jul-12 16:25:17
MMMM dd = July 18
MMMM dd = July 18
yyyy'-'MM'-'dd'T'HH':'mm':'ss.fffffffK = 2012-07-18T16:25:17.0961142-07:00
yyyy'-'MM'-'dd'T'HH':'mm':'ss.fffffffK = 2012-07-18T16:25:17.0961142-07:00
ddd, dd MMM yyyy HH':'mm':'ss 'GMT' = Wed, 18 Jul 2012 16:25:17 GMT
ddd, dd MMM yyyy HH':'mm':'ss 'GMT' = Wed, 18 Jul 2012 16:25:17 GMT
yyyy'-'MM'-'dd'T'HH':'mm':'ss = 2012-07-18T16:25:17
h:mm tt = 4:25 PM
hh:mm tt = 04:25 PM
H:mm = 16:25
HH:mm = 16:25
h:mm:ss tt = 4:25:17 PM
hh:mm:ss tt = 04:25:17 PM
H:mm:ss = 16:25:17
HH:mm:ss = 16:25:17
yyyy'-'MM'-'dd HH':'mm':'ss'Z' = 2012-07-18 16:25:17Z
dddd, MMMM dd, yyyy h:mm:ss tt = Wednesday, July 18, 2012 4:25:17 PM
dddd, MMMM dd, yyyy hh:mm:ss tt = Wednesday, July 18, 2012 04:25:17 PM
dddd, MMMM dd, yyyy H:mm:ss = Wednesday, July 18, 2012 16:25:17
dddd, MMMM dd, yyyy HH:mm:ss = Wednesday, July 18, 2012 16:25:17
MMMM dd, yyyy h:mm:ss tt = July 18, 2012 4:25:17 PM
MMMM dd, yyyy hh:mm:ss tt = July 18, 2012 04:25:17 PM
MMMM dd, yyyy H:mm:ss = July 18, 2012 16:25:17
MMMM dd, yyyy HH:mm:ss = July 18, 2012 16:25:17
dddd, dd MMMM, yyyy h:mm:ss tt = Wednesday, 18 July, 2012 4:25:17 PM
dddd, dd MMMM, yyyy hh:mm:ss tt = Wednesday, 18 July, 2012 04:25:17 PM
dddd, dd MMMM, yyyy H:mm:ss = Wednesday, 18 July, 2012 16:25:17
dddd, dd MMMM, yyyy HH:mm:ss = Wednesday, 18 July, 2012 16:25:17
dd MMMM, yyyy h:mm:ss tt = 18 July, 2012 4:25:17 PM
dd MMMM, yyyy hh:mm:ss tt = 18 July, 2012 04:25:17 PM
dd MMMM, yyyy H:mm:ss = 18 July, 2012 16:25:17
dd MMMM, yyyy HH:mm:ss = 18 July, 2012 16:25:17
MMMM, yyyy = July, 2012
MMMM, yyyy = July, 2012

I'm not sure why several patterns are repeated.

回答2:

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. [C#]

    // 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:

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

    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

回答3:

DateTime.Now.ToString("D") displays "Wednesday, July 18, 2012"
DateTime.Now.ToString("d") displays "7/18/2012"
DateTime.Now.ToString("F") displays "Wednesday, July 18, 2012 3:57:13 PM"
DateTime.Now.ToString("f") displays "Wednesday, July 18, 2012 3:57 PM"
DateTime.Now.ToString("G") displays "7/18/2012 3:57 PM"
DateTime.Now.ToString("g") displays "7/18/2012 3:57:30 PM"
DateTime.Now.ToString("M") displays "July 18"
DateTime.Now.ToString("R") displays "Wed, 18 Jul 2012 15:57:55 GMT"
DateTime.Now.ToString("s") displays "2012-07-18T15:58:02"
DateTime.Now.ToString("T") displays "3:56:38 PM"
DateTime.Now.ToString("t") displays "3:56 PM"
DateTime.Now.ToString("U") displays "Wednesday, July 18, 2012 10:58:09 PM"
DateTime.Now.ToString("u") displays "2012-07-18 15:58:17Z"
DateTime.Now.ToString("Y") displays "July, 2012"
DateTime.Now.ToString("42") displays "42"

回答4:

I did this once and... What I did was create a Windows Application, put a Label and a TextBox on it and attached onto the TextBox Change event a

Label1.Text = DateTime.Now.ToString(TextBox1.Text)

Pretty simple and helps you try out things instantly.