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Custom DateTime Formatting in C#

Introduction

This example shows how to format DateTime using String.Format method. All formatting can be done also using DateTime.ToString method or string interpolation.

There are following custom format specifiers:

  • y (year)
  • M (month)
  • d (day)
  • h (hour, in 12 hours)
  • H (hour, in 24 hours)
  • m (minute)
  • s (second)
  • f (second fraction)
  • F (second fraction, trailing zeroes are trimmed)
  • t (AM or PM)
  • z (timezone)

Examples

Custom DateTime Formatting

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

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// created DateTime with value: 2008-03-09 16:05:07.123
var example = new DateTime(2008, 3, 9, 16, 5, 7, 123);

String.Format("{0:y yy yyy yyyy}", example);  // "8 08 008 2008"    year
String.Format("{0:M MM MMM MMMM}", example);  // "3 03 Mar March"   month
String.Format("{0:d dd ddd dddd}", example);  // "9 09 Sun Sunday"  day
String.Format("{0:h hh H HH}",     example);  // "4 04 16 16"       hour, in 12/24 hours
String.Format("{0:m mm}",          example);  // "5 05"             minute
String.Format("{0:s ss}",          example);  // "7 07"             second
String.Format("{0:f ff fff ffff}", example);  // "1 12 123 1230"    second fraction
String.Format("{0:F FF FFF FFFF}", example);  // "1 12 123 123"     second fraction, trailing zeros are trimmed
String.Format("{0:t tt}",          example);  // "P PM"             AM or PM
String.Format("{0:z zz zzz}",      example);  // "-6 -06 -06:00"    timezone

You can use also time sepatator : (colon) and date separator / (slash). These characters will be rewritten to characters defined in the current DateTimeForma­tInfo.DateSepa­rator and DateTimeForma­tInfo.TimeSepa­rator.

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

Here are some examples of custom date and time formatting.

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String.Format("{0:M/d/yyyy}", example);            // "3/9/2008"
String.Format("{0:MM/dd/yyyy}", example);          // "03/09/2008"

String.Format("{0:ddd, MMM d, yyyy}", example);    // "Sun, Mar 9, 2008"
String.Format("{0:dddd, MMMM d, yyyy}", example);  // "Sunday, March 9, 2008"

String.Format("{0:MM/dd/yy}", example);            // "03/09/08"
String.Format("{0:MM/dd/yyyy}", example);          // "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.

SpecifierPattern PropertyPattern Value (for en-US culture)
tShortTimePatternh:mm tt
dShortDatePatternM/d/yyyy
TLongTimePatternh:mm:ss tt
DLongDatePatterndddd, MMMM dd, yyyy
f(combination of D and t)dddd, MMMM dd, yyyy h:mm tt
FFullDateTimePatterndddd, 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, MMonthDayPatternMMMM dd
y, YYearMonthPatternMMMM, yyyy
r, RYearMonthPatternddd, dd MMM, yyyy, HH':'mm':'ss 'GMT' (*)
sSortableDateTimePatternyyyy'-'MM'-'dd'T'HH':'mm':'ss (*)
uUniversalSortableDateTimePatternyyyy'-'MM'-'dd HH':'mm':'ss'Z' (*)

NOTE: (*) = culture independent

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

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

Sources

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