1DateTime(3) User Contributed Perl Documentation DateTime(3)
2
6 DateTime - A date and time object for Perl
7
9 version 1.52
10
12 use DateTime;
13 $dt = DateTime->new(
15 year => 1964,
16 month => 10,
17 day => 16,
18 hour => 16,
19 minute => 12,
20 second => 47,
21 nanosecond => 500000000,
22 time_zone => 'Asia/Taipei',
23 );
24 $dt = DateTime->from_epoch( epoch => $epoch );
26 $dt = DateTime->now; # same as ( epoch => time() )
27 $year = $dt->year;
29 $month = $dt->month; # 1-12
30 $day = $dt->day; # 1-31
32 $dow = $dt->day_of_week; # 1-7 (Monday is 1)
34 $hour = $dt->hour; # 0-23
36 $minute = $dt->minute; # 0-59
37 $second = $dt->second; # 0-61 (leap seconds!)
39 $doy = $dt->day_of_year; # 1-366 (leap years)
41 $doq = $dt->day_of_quarter; # 1..
43 $qtr = $dt->quarter; # 1-4
45 # all of the start-at-1 methods above have corresponding start-at-0
47 # methods, such as $dt->day_of_month_0, $dt->month_0 and so on
48 $ymd = $dt->ymd; # 2002-12-06
50 $ymd = $dt->ymd('/'); # 2002/12/06
51 $mdy = $dt->mdy; # 12-06-2002
53 $mdy = $dt->mdy('/'); # 12/06/2002
54 $dmy = $dt->dmy; # 06-12-2002
56 $dmy = $dt->dmy('/'); # 06/12/2002
57 $hms = $dt->hms; # 14:02:29
59 $hms = $dt->hms('!'); # 14!02!29
60 $is_leap = $dt->is_leap_year;
62 # these are localizable, see Locales section
64 $month_name = $dt->month_name; # January, February, ...
65 $month_abbr = $dt->month_abbr; # Jan, Feb, ...
66 $day_name = $dt->day_name; # Monday, Tuesday, ...
67 $day_abbr = $dt->day_abbr; # Mon, Tue, ...
68 # May not work for all possible datetime, see the docs on this
70 # method for more details.
71 $epoch_time = $dt->epoch;
72 $dt2 = $dt + $duration_object;
74 $dt3 = $dt - $duration_object;
76 $duration_object = $dt - $dt2;
78 $dt->set( year => 1882 );
80 $dt->set_time_zone( 'America/Chicago' );
82 $dt->set_formatter( $formatter );
84
86 DateTime is a class for the representation of date/time combinations,
87 and is part of the Perl DateTime project. For details on this project
88 please see <http://datetime.perl.org/>. The DateTime site has a FAQ
89 which may help answer many "how do I do X?" questions. The FAQ is at
90 <http://datetime.perl.org/wiki/datetime/page/FAQ>.
91 It represents the Gregorian calendar, extended backwards in time before
93 its creation (in 1582). This is sometimes known as the "proleptic
94 Gregorian calendar". In this calendar, the first day of the calendar
95 (the epoch), is the first day of year 1, which corresponds to the date
96 which was (incorrectly) believed to be the birth of Jesus Christ.
97 The calendar represented does have a year 0, and in that way differs
99 from how dates are often written using "BCE/CE" or "BC/AD".
100 For infinite datetimes, please see the DateTime::Infinite module.
102
104 0-based Versus 1-based Numbers
105 The DateTime.pm module follows a simple logic for determining whether
106 or not a given number is 0-based or 1-based.
107 Month, day of month, day of week, and day of year are 1-based. Any
109 method that is 1-based also has an equivalent 0-based method ending in
110 "_0". So for example, this class provides both "day_of_week()" and
111 "day_of_week_0()" methods.
112 The "day_of_week_0()" method still treats Monday as the first day of
114 the week.
115 All time-related numbers such as hour, minute, and second are 0-based.
117 Years are neither, as they can be both positive or negative, unlike any
119 other datetime component. There is a year 0.
120 There is no "quarter_0()" method.
122 Error Handling
124 Some errors may cause this module to die with an error string. This can
125 only happen when calling constructor methods, methods that change the
126 object, such as "set()", or methods that take parameters. Methods that
127 retrieve information about the object, such as "year()" or "epoch()",
128 will never die.
129 Locales
131 All the object methods which return names or abbreviations return data
132 based on a locale. This is done by setting the locale when constructing
133 a DateTime object. If this is not set, then "en-US" is used.
134 Floating DateTimes
136 The default time zone for new DateTime objects, except where stated
137 otherwise, is the "floating" time zone. This concept comes from the
138 iCal standard. A floating datetime is one which is not anchored to any
139 particular time zone. In addition, floating datetimes do not include
140 leap seconds, since we cannot apply them without knowing the datetime's
141 time zone.
142 The results of date math and comparison between a floating datetime and
144 one with a real time zone are not really valid, because one includes
145 leap seconds and the other does not. Similarly, the results of datetime
146 math between two floating datetimes and two datetimes with time zones
147 are not really comparable.
148 If you are planning to use any objects with a real time zone, it is
150 strongly recommended that you do not mix these with floating datetimes.
151 Math
153 If you are going to be doing date math, please read the section "How
154 DateTime Math Works".
155 Determining the Local Time Zone Can Be Slow
157 If $ENV{TZ} is not set, it may involve reading a number of files in
158 /etc or elsewhere. If you know that the local time zone won't change
159 while your code is running, and you need to make many objects for the
160 local time zone, it is strongly recommended that you retrieve the local
161 time zone once and cache it:
162 our $App::LocalTZ = DateTime::TimeZone->new( name => 'local' );
164 ... # then everywhere else
166 my $dt = DateTime->new( ..., time_zone => $App::LocalTZ );
168 DateTime itself does not do this internally because local time zones
170 can change, and there's no good way to determine if it's changed
171 without doing all the work to look it up.
172 Do not try to use named time zones (like "America/Chicago") with dates
174 very far in the future (thousands of years). The current implementation
175 of "DateTime::TimeZone" will use a huge amount of memory calculating
176 all the DST changes from now until the future date. Use UTC or the
177 floating time zone and you will be safe.
178 Globally Setting a Default Time Zone
180 Warning: This is very dangerous. Do this at your own risk!
181 By default, "DateTime" uses either the floating time zone or UTC for
183 newly created objects, depending on the constructor.
184 You can force "DateTime" to use a different time zone by setting the
186 "PERL_DATETIME_DEFAULT_TZ" environment variable.
187 As noted above, this is very dangerous, as it affects all code that
189 creates a "DateTime" object, including modules from CPAN. If those
190 modules expect the normal default, then setting this can cause
191 confusing breakage or subtly broken data. Before setting this variable,
192 you are strongly encouraged to audit your CPAN dependencies to see how
193 they use "DateTime". Try running the test suite for each dependency
194 with this environment variable set before using this in production.
195 Upper and Lower Bounds
197 Internally, dates are represented the number of days before or after
198 0001-01-01. This is stored as an integer, meaning that the upper and
199 lower bounds are based on your Perl's integer size ($Config{ivsize}).
200 The limit on 32-bit systems is around 2^29 days, which gets you to year
202 (+/-)1,469,903. On a 64-bit system you get 2^62 days,
203 (+/-)12,626,367,463,883,278 (12.626 quadrillion).
204
206 DateTime provide many methods. The documentation breaks them down into
207 groups based on what they do (constructor, accessors, modifiers, etc.).
208 Constructors
210 All constructors can die when invalid parameters are given.
211 Warnings
213 Currently, constructors will warn if you try to create a far future
215 DateTime (year >= 5000) with any time zone besides floating or UTC.
216 This can be very slow if the time zone has future DST transitions that
217 need to be calculated. If the date is sufficiently far in the future
218 this can be really slow (minutes).
219 All warnings from DateTime use the "DateTime" category and can be
221 suppressed with:
222 no warnings 'DateTime';
224 This warning may be removed in the future if DateTime::TimeZone is made
226 much faster.
227 DateTime->new( ... )
229 This class method accepts parameters for each date and time component:
231 "year", "month", "day", "hour", "minute", "second", "nanosecond". It
232 also accepts "locale", "time_zone", and "formatter" parameters.
233 my $dt = DateTime->new(
235 year => 1966,
236 month => 10,
237 day => 25,
238 hour => 7,
239 minute => 15,
240 second => 47,
241 nanosecond => 500000000,
242 time_zone => 'America/Chicago',
243 );
244 DateTime validates the "month", "day", "hour", "minute", and "second",
246 and "nanosecond" parameters. The valid values for these parameters are:
247 · month
249 An integer from 1-12.
251 · day
253 An integer from 1-31, and it must be within the valid range of
255 days for the specified month.
256 · hour
258 An integer from 0-23.
260 · minute
262 An integer from 0-59.
264 · second
266 An integer from 0-61 (to allow for leap seconds). Values of 60
268 or 61 are only allowed when they match actual leap seconds.
269 · nanosecond
271 An integer >= 0. If this number is greater than 1 billion, it
273 will be normalized into the second value for the DateTime
274 object.
275 Invalid parameter types (like an array reference) will cause the
277 constructor to die.
278 The value for seconds may be from 0 to 61, to account for leap seconds.
280 If you give a value greater than 59, DateTime does check to see that it
281 really matches a valid leap second.
282 All of the parameters are optional except for "year". The "month" and
284 "day" parameters both default to 1, while the "hour", "minute",
285 "second", and "nanosecond" parameters all default to 0.
286 The "locale" parameter should be a string containing a locale code,
288 like "en-US" or "zh-Hant-TW", or an object returned by
289 "DateTime::Locale->load". See the DateTime::Locale documentation for
290 details.
291 The "time_zone" parameter can be either a string or a
293 "DateTime::TimeZone" object. A string will simply be passed to the
294 "DateTime::TimeZone->new" method as its "name" parameter. This string
295 may be an Olson DB time zone name ("America/Chicago"), an offset string
296 ("+0630"), or the words "floating" or "local". See the
297 "DateTime::TimeZone" documentation for more details.
298 The default time zone is "floating".
300 The "formatter" can be either a scalar or an object, but the class
302 specified by the scalar or the object must implement a
303 "format_datetime()" method.
304 Parsing Dates
306 This module does not parse dates! That means there is no constructor to
308 which you can pass things like "March 3, 1970 12:34".
309 Instead, take a look at the various "DateTime::Format::*" modules on
311 CPAN. These parse all sorts of different date formats, and you're bound
312 to find something that can handle your particular needs.
313 Ambiguous Local Times
315 Because of Daylight Saving Time, it is possible to specify a local time
317 that is ambiguous. For example, in the US in 2003, the transition from
318 to saving to standard time occurred on October 26, at 02:00:00 local
319 time. The local clock changed from 01:59:59 (saving time) to 01:00:00
320 (standard time). This means that the hour from 01:00:00 through
321 01:59:59 actually occurs twice, though the UTC time continues to move
322 forward.
323 If you specify an ambiguous time, then the latest UTC time is always
325 used, in effect always choosing standard time. In this case, you can
326 simply subtract an hour to the object in order to move to saving time,
327 for example:
328 # This object represent 01:30:00 standard time
330 my $dt = DateTime->new(
331 year => 2003,
332 month => 10,
333 day => 26,
334 hour => 1,
335 minute => 30,
336 second => 0,
337 time_zone => 'America/Chicago',
338 );
339 print $dt->hms; # prints 01:30:00
341 # Now the object represent 01:30:00 saving time
343 $dt->subtract( hours => 1 );
344 print $dt->hms; # still prints 01:30:00
346 Alternately, you could create the object with the UTC time zone, and
348 then call the "set_time_zone()" method to change the time zone. This is
349 a good way to ensure that the time is not ambiguous.
350 Invalid Local Times
352 Another problem introduced by Daylight Saving Time is that certain
354 local times just do not exist. For example, in the US in 2003, the
355 transition from standard to saving time occurred on April 6, at the
356 change to 2:00:00 local time. The local clock changes from 01:59:59
357 (standard time) to 03:00:00 (saving time). This means that there is no
358 02:00:00 through 02:59:59 on April 6!
359 Attempting to create an invalid time currently causes a fatal error.
361 This may change in future version of this module.
362 DateTime->from_epoch( epoch => $epoch, ... )
364 This class method can be used to construct a new DateTime object from
366 an epoch time instead of components. Just as with the "new()" method,
367 it accepts "time_zone", "locale", and "formatter" parameters.
368 If the epoch value is a floating-point value, it will be rounded to
370 nearest microsecond.
371 By default, the returned object will be in the UTC time zone.
373 DateTime->now( ... )
375 This class method is equivalent to calling "from_epoch()" with the
377 value returned from Perl's "time()" function. Just as with the "new()"
378 method, it accepts "time_zone" and "locale" parameters.
379 By default, the returned object will be in the UTC time zone.
381 DateTime->today( ... )
383 This class method is equivalent to:
385 DateTime->now(@_)->truncate( to => 'day' );
387 DateTime->from_object( object => $object, ... )
389 This class method can be used to construct a new DateTime object from
391 any object that implements the "utc_rd_values()" method. All
392 "DateTime::Calendar" modules must implement this method in order to
393 provide cross-calendar compatibility. This method accepts a "locale"
394 and "formatter" parameter
395 If the object passed to this method has a "time_zone()" method, that is
397 used to set the time zone of the newly created "DateTime.pm" object.
398 Otherwise, the returned object will be in the floating time zone.
400 DateTime->last_day_of_month( ... )
402 This constructor takes the same arguments as can be given to the
404 "new()" method, except for "day". Additionally, both "year" and "month"
405 are required.
406 DateTime->from_day_of_year( ... )
408 This constructor takes the same arguments as can be given to the
410 "new()" method, except that it does not accept a "month" or "day"
411 argument. Instead, it requires both "year" and "day_of_year". The day
412 of year must be between 1 and 366, and 366 is only allowed for leap
413 years.
414 $dt->clone()
416 This object method returns a new object that is replica of the object
418 upon which the method is called.
419 "Get" Methods
421 This class has many methods for retrieving information about an object.
422 $dt->year()
424 Returns the year.
426 $dt->ce_year()
428 Returns the year according to the BCE/CE numbering system. The year
430 before year 1 in this system is year -1, aka "1 BCE".
431 $dt->era_name()
433 Returns the long name of the current era, something like "Before
435 Christ". See the Locales section for more details.
436 $dt->era_abbr()
438 Returns the abbreviated name of the current era, something like "BC".
440 See the Locales section for more details.
441 $dt->christian_era()
443 Returns a string, either "BC" or "AD", according to the year.
445 $dt->secular_era()
447 Returns a string, either "BCE" or "CE", according to the year.
449 $dt->year_with_era()
451 Returns a string containing the year immediately followed by its era
453 abbreviation. The year is the absolute value of "ce_year()", so that
454 year 1 is "1AD" and year 0 is "1BC".
455 $dt->year_with_christian_era()
457 Like "year_with_era()", but uses the christian_era() method to get the
459 era name.
460 $dt->year_with_secular_era()
462 Like "year_with_era()", but uses the secular_era() method to get the
464 era name.
465 $dt->month()
467 Returns the month of the year, from 1..12.
469 Also available as "$dt->mon()".
471 $dt->month_name()
473 Returns the name of the current month. See the Locales section for more
475 details.
476 $dt->month_abbr()
478 Returns the abbreviated name of the current month. See the Locales
480 section for more details.
481 $dt->day()
483 Returns the day of the month, from 1..31.
485 Also available as "$dt->mday()" and "$dt->day_of_month()".
487 $dt->day_of_week()
489 Returns the day of the week as a number, from 1..7, with 1 being Monday
491 and 7 being Sunday.
492 Also available as "$dt->wday()" and "$dt->dow()".
494 $dt->local_day_of_week()
496 Returns the day of the week as a number, from 1..7. The day
498 corresponding to 1 will vary based on the locale.
499 $dt->day_name()
501 Returns the name of the current day of the week. See the Locales
503 section for more details.
504 $dt->day_abbr()
506 Returns the abbreviated name of the current day of the week. See the
508 Locales section for more details.
509 $dt->day_of_year()
511 Returns the day of the year.
513 Also available as "$dt->doy()".
515 $dt->quarter()
517 Returns the quarter of the year, from 1..4.
519 $dt->quarter_name()
521 Returns the name of the current quarter. See the Locales section for
523 more details.
524 $dt->quarter_abbr()
526 Returns the abbreviated name of the current quarter. See the Locales
528 section for more details.
529 $dt->day_of_quarter()
531 Returns the day of the quarter.
533 Also available as "$dt->doq()".
535 $dt->weekday_of_month()
537 Returns a number from 1..5 indicating which week day of the month this
539 is. For example, June 9, 2003 is the second Monday of the month, and so
540 this method returns 2 for that day.
541 $dt->ymd( $optional_separator ), $dt->mdy(...), $dt->dmy(...)
543 Each method returns the year, month, and day, in the order indicated by
545 the method name. Years are zero-padded to four digits. Months and days
546 are 0-padded to two digits.
547 By default, the values are separated by a dash (-), but this can be
549 overridden by passing a value to the method.
550 The "$dt->ymd()" method is also available as "$dt->date()".
552 $dt->hour()
554 Returns the hour of the day, from 0..23.
556 $dt->hour_1()
558 Returns the hour of the day, from 1..24.
560 $dt->hour_12()
562 Returns the hour of the day, from 1..12.
564 $dt->hour_12_0()
566 Returns the hour of the day, from 0..11.
568 $dt->am_or_pm()
570 Returns the appropriate localized abbreviation, depending on the
572 current hour.
573 $dt->minute()
575 Returns the minute of the hour, from 0..59.
577 Also available as "$dt->min()".
579 $dt->second()
581 Returns the second, from 0..61. The values 60 and 61 are used for leap
583 seconds.
584 Also available as "$dt->sec()".
586 $dt->fractional_second()
588 Returns the second, as a real number from 0.0 until 61.999999999
590 The values 60 and 61 are used for leap seconds.
592 $dt->millisecond()
594 Returns the fractional part of the second as milliseconds (1E-3
596 seconds).
597 Half a second is 500 milliseconds.
599 This value will always be rounded down to the nearest integer.
601 $dt->microsecond()
603 Returns the fractional part of the second as microseconds (1E-6
605 seconds).
606 Half a second is 500_000 microseconds.
608 This value will always be rounded down to the nearest integer.
610 $dt->nanosecond()
612 Returns the fractional part of the second as nanoseconds (1E-9
614 seconds).
615 Half a second is 500_000_000 nanoseconds.
617 $dt->hms( $optional_separator )
619 Returns the hour, minute, and second, all zero-padded to two digits.
621 If no separator is specified, a colon (:) is used by default.
622 Also available as "$dt->time()".
624 $dt->datetime( $optional_separator )
626 This method is equivalent to:
628 $dt->ymd('-') . 'T' . $dt->hms(':')
630 The $optional_separator parameter allows you to override the separator
632 between the date and time, for e.g. "$dt->datetime(q{ })".
633 This method is also available as "$dt->iso8601()", but it's not really
635 a very good ISO8601 format, as it lacks a time zone. If called as
636 "$dt->iso8601()" you cannot change the separator, as ISO8601 specifies
637 that "T" must be used to separate them.
638 $dt->stringify()
640 This method returns a stringified version of the object. It is how
642 stringification overloading is implemented. If the object has a
643 formatter, then its "format_datetime()" method is used to produce a
644 string. Otherwise, this method calls "$dt->iso8601()" to produce a
645 string. See "Formatters And Stringification" for details.
646 $dt->is_leap_year()
648 This method returns a true or false value indicating whether or not the
650 datetime object is in a leap year.
651 $dt->is_last_day_of_month()
653 This method returns a true or false value indicating whether or not the
655 datetime object is the last day of the month.
656 $dt->is_last_day_of_quarter()
658 This method returns a true or false value indicating whether or not the
660 datetime object is the last day of the quarter.
661 $dt->is_last_day_of_year()
663 This method returns a true or false value indicating whether or not the
665 datetime object is the last day of the year.
666 $dt->month_length()
668 This method returns the number of days in the current month.
670 $dt->quarter_length()
672 This method returns the number of days in the current quarter.
674 $dt->year_length()
676 This method returns the number of days in the current year.
678 $dt->week()
680 ($week_year, $week_number) = $dt->week;
682 Returns information about the calendar week which contains this
684 datetime object. The values returned by this method are also available
685 separately through the week_year and week_number methods.
686 The first week of the year is defined by ISO as the one which contains
688 the fourth day of January, which is equivalent to saying that it's the
689 first week to overlap the new year by at least four days.
690 Typically the week year will be the same as the year that the object is
692 in, but dates at the very beginning of a calendar year often end up in
693 the last week of the prior year, and similarly, the final few days of
694 the year may be placed in the first week of the next year.
695 $dt->week_year()
697 Returns the year of the week. See "$dt->week()" for details.
699 $dt->week_number()
701 Returns the week of the year, from 1..53. See "$dt->week()" for
703 details.
704 $dt->week_of_month()
706 The week of the month, from 0..5. The first week of the month is the
708 first week that contains a Thursday. This is based on the ICU
709 definition of week of month, and correlates to the ISO8601 week of year
710 definition. A day in the week before the week with the first Thursday
711 will be week 0.
712 $dt->jd(), $dt->mjd()
714 These return the Julian Day and Modified Julian Day, respectively. The
716 value returned is a floating point number. The fractional portion of
717 the number represents the time portion of the datetime.
718 $dt->time_zone()
720 This returns the "DateTime::TimeZone" object for the datetime object.
722 $dt->offset()
724 This returns the offset from UTC, in seconds, of the datetime object
726 according to the time zone.
727 $dt->is_dst()
729 Returns a boolean indicating whether or not the datetime object is
731 currently in Daylight Saving Time or not.
732 $dt->time_zone_long_name()
734 This is a shortcut for "$dt->time_zone->name". It's provided so that
736 one can use "%{time_zone_long_name}" as a strftime format specifier.
737 $dt->time_zone_short_name()
739 This method returns the time zone abbreviation for the current time
741 zone, such as "PST" or "GMT". These names are not definitive, and
742 should not be used in any application intended for general use by users
743 around the world.
744 $dt->strftime( $format, ... )
746 This method implements functionality similar to the "strftime()" method
748 in C. However, if given multiple format strings, then it will return
749 multiple scalars, one for each format string.
750 See the "strftime Patterns" section for a list of all possible strftime
752 patterns.
753 If you give a pattern that doesn't exist, then it is simply treated as
755 text.
756 Note that any deviation from the POSIX standard is probably a bug.
758 DateTime should match the output of "POSIX::strftime" for any given
759 pattern.
760 $dt->format_cldr( $format, ... )
762 This method implements formatting based on the CLDR date patterns. If
764 given multiple format strings, then it will return multiple scalars,
765 one for each format string.
766 See the "CLDR Patterns" section for a list of all possible CLDR
768 patterns.
769 If you give a pattern that doesn't exist, then it is simply treated as
771 text.
772 $dt->epoch()
774 Returns the UTC epoch value for the datetime object. DateTimes before
776 the start of the epoch will be returned as a negative number.
777 The return value from this method is always an integer number of
779 seconds.
780 Since the epoch does not account for leap seconds, the epoch time for
782 1972-12-31T23:59:60 (UTC) is exactly the same as that for
783 1973-01-01T00:00:00.
784 $dt->hires_epoch()
786 Returns the epoch as a floating point number. The floating point
788 portion of the value represents the nanosecond value of the object.
789 This method is provided for compatibility with the "Time::HiRes"
790 module.
791 Note that this method suffers from the imprecision of floating point
793 numbers, and the result may end up rounded to an arbitrary degree
794 depending on your platform.
795 my $dt = DateTime->new( year => 2012, nanosecond => 4 );
797 say $dt->hires_epoch();
798 On my system, this simply prints 1325376000 because adding 0.000000004
800 to 1325376000 returns 1325376000.
801 $dt->is_finite(), $dt->is_infinite()
803 These methods allow you to distinguish normal datetime objects from
805 infinite ones. Infinite datetime objects are documented in
806 DateTime::Infinite.
807 $dt->utc_rd_values()
809 Returns the current UTC Rata Die days, seconds, and nanoseconds as a
811 three element list. This exists primarily to allow other calendar
812 modules to create objects based on the values provided by this object.
813 $dt->local_rd_values()
815 Returns the current local Rata Die days, seconds, and nanoseconds as a
817 three element list. This exists for the benefit of other modules which
818 might want to use this information for date math, such as
819 "DateTime::Event::Recurrence".
820 $dt->leap_seconds()
822 Returns the number of leap seconds that have happened up to the
824 datetime represented by the object. For floating datetimes, this always
825 returns 0.
826 $dt->utc_rd_as_seconds()
828 Returns the current UTC Rata Die days and seconds purely as seconds.
830 This number ignores any fractional seconds stored in the object, as
831 well as leap seconds.
832 $dt->locale()
834 Returns the current locale object.
836 $dt->formatter()
838 Returns current formatter object or class. See "Formatters And
840 Stringification" for details.
841 "Set" Methods
843 The remaining methods provided by "DateTime.pm", except where otherwise
844 specified, return the object itself, thus making method chaining
845 possible. For example:
846 my $dt = DateTime->now->set_time_zone( 'Australia/Sydney' );
848 my $first = DateTime
850 ->last_day_of_month( year => 2003, month => 3 )
851 ->add( days => 1 )
852 ->subtract( seconds => 1 );
853 $dt->set( .. )
855 This method can be used to change the local components of a date time.
857 This method accepts any parameter allowed by the "new()" method except
858 for "locale" or "time_zone". Use "set_locale()" and "set_time_zone()"
859 for those instead.
860 This method performs parameter validation just like the "new()" method.
862 Do not use this method to do date math. Use the "add()" and
864 "subtract()" methods instead.
865 $dt->set_year(), $dt->set_month(), etc.
867 DateTime has a "set_*" method for every item that can be passed to the
869 constructor:
870 · $dt->set_year()
872 · $dt->set_month()
874 · $dt->set_day()
876 · $dt->set_hour()
878 · $dt->set_minute()
880 · $dt->set_second()
882 · $dt->set_nanosecond()
884 These are shortcuts to calling "set()" with a single key. They all take
886 a single parameter.
887 $dt->truncate( to => ... )
889 This method allows you to reset some of the local time components in
891 the object to their "zero" values. The "to" parameter is used to
892 specify which values to truncate, and it may be one of "year",
893 "quarter", "month", "week", "local_week", "day", "hour", "minute", or
894 "second".
895 For example, if "month" is specified, then the local day becomes 1, and
897 the hour, minute, and second all become 0.
898 If "week" is given, then the datetime is set to the Monday of the week
900 in which it occurs, and the time components are all set to 0. If you
901 truncate to "local_week", then the first day of the week is locale-
902 dependent. For example, in the "en-US" locale, the first day of the
903 week is Sunday.
904 $dt->set_locale( $locale )
906 Sets the object's locale. You can provide either a locale code like
908 "en-US" or an object returned by "DateTime::Locale->load".
909 $dt->set_time_zone( $tz )
911 This method accepts either a time zone object or a string that can be
913 passed as the "name" parameter to "DateTime::TimeZone->new()". If the
914 new time zone's offset is different from the old time zone, then the
915 local time is adjusted accordingly.
916 For example:
918 my $dt = DateTime->new(
920 year => 2000,
921 month => 5,
922 day => 10,
923 hour => 15,
924 minute => 15,
925 time_zone => 'America/Los_Angeles',
926 );
927 print $dt->hour; # prints 15
929 $dt->set_time_zone( 'America/Chicago' );
931 print $dt->hour; # prints 17
933 If the old time zone was a floating time zone, then no adjustments to
935 the local time are made, except to account for leap seconds. If the new
936 time zone is floating, then the UTC time is adjusted in order to leave
937 the local time untouched.
938 Fans of Tsai Ming-Liang's films will be happy to know that this does
940 work:
941 my $dt = DateTime->now( time_zone => 'Asia/Taipei' );
943 $dt->set_time_zone( 'Europe/Paris' );
945 Yes, now we can know "ni3 na4 bian1 ji2dian3?"
947 $dt->set_formatter( $formatter )
949 Set the formatter for the object. See "Formatters And Stringification"
951 for details.
952 You can set this to "undef" to revert to the default formatter.
954 Math Methods
956 Like the set methods, math related methods always return the object
957 itself, to allow for chaining:
958 $dt->add( days => 1 )->subtract( seconds => 1 );
960 $dt->duration_class()
962 This returns "DateTime::Duration", but exists so that a subclass of
964 "DateTime.pm" can provide a different value.
965 $dt->add_duration( $duration_object )
967 This method adds a "DateTime::Duration" to the current datetime. See
969 the DateTime::Duration docs for more details.
970 $dt->add( parameters for DateTime::Duration )
972 This method is syntactic sugar around the "add_duration()" method. It
974 simply creates a new "DateTime::Duration" object using the parameters
975 given, and then calls the "add_duration()" method.
976 $dt->add( $duration_object )
978 A synonym of "$dt->add_duration( $duration_object )".
980 $dt->subtract_duration( $duration_object )
982 When given a "DateTime::Duration" object, this method simply calls
984 "inverse()" on that object and passes that new duration to the
985 "add_duration" method.
986 $dt->subtract( DateTime::Duration->new parameters )
988 Like "add()", this is syntactic sugar for the "subtract_duration()"
990 method.
991 $dt->subtract( $duration_object )
993 A synonym of "$dt->subtract_duration( $duration_object )".
995 $dt->subtract_datetime( $datetime )
997 This method returns a new "DateTime::Duration" object representing the
999 difference between the two dates. The duration is relative to the
1000 object from which $datetime is subtracted. For example:
1001 2003-03-15 00:00:00.00000000
1003 - 2003-02-15 00:00:00.00000000
1004 -------------------------------
1005 = 1 month
1006 Note that this duration is not an absolute measure of the amount of
1008 time between the two datetimes, because the length of a month varies,
1009 as well as due to the presence of leap seconds.
1010 The returned duration may have deltas for months, days, minutes,
1012 seconds, and nanoseconds.
1013 $dt->delta_md( $datetime )
1015 $dt->delta_days( $datetime )
1017 Each of these methods returns a new "DateTime::Duration" object
1019 representing some portion of the difference between two datetimes. The
1020 "delta_md()" method returns a duration which contains only the month
1021 and day portions of the duration is represented. The "delta_days()"
1022 method returns a duration which contains only days.
1023 The "delta_md" and "delta_days" methods truncate the duration so that
1025 any fractional portion of a day is ignored. Both of these methods
1026 operate on the date portion of a datetime only, and so effectively
1027 ignore the time zone.
1028 Unlike the subtraction methods, these methods always return a positive
1030 (or zero) duration.
1031 $dt->delta_ms( $datetime )
1033 Returns a duration which contains only minutes and seconds. Any day and
1035 month differences to minutes are converted to minutes and seconds. This
1036 method also always return a positive (or zero) duration.
1037 $dt->subtract_datetime_absolute( $datetime )
1039 This method returns a new "DateTime::Duration" object representing the
1041 difference between the two dates in seconds and nanoseconds. This is
1042 the only way to accurately measure the absolute amount of time between
1043 two datetimes, since units larger than a second do not represent a
1044 fixed number of seconds.
1045 Note that because of leap seconds, this may not return the same result
1047 as doing this math based on the value returned by "$dt->epoch()".
1048 $dt->is_between( $lower, $upper )
1050 Checks whether $dt is strictly between two other DateTime objects.
1052 "Strictly" means that $dt must be greater than $lower and less than
1054 $upper. If it is equal to either object then this method returns false.
1055 Class Methods
1057 DateTime->DefaultLocale( $locale )
1058 This can be used to specify the default locale to be used when creating
1060 DateTime objects. If unset, then "en-US" is used.
1061 DateTime->compare( $dt1, $dt2 ), DateTime->compare_ignore_floating(
1063 $dt1, $dt2 )
1064 $cmp = DateTime->compare( $dt1, $dt2 );
1066 $cmp = DateTime->compare_ignore_floating( $dt1, $dt2 );
1068 Compare two DateTime objects. The semantics are compatible with Perl's
1070 "sort()" function; it returns -1 if $dt1 < $dt2, 0 if $dt1 == $dt2, 1
1071 if $dt1 > $dt2.
1072 If one of the two DateTime objects has a floating time zone, it will
1074 first be converted to the time zone of the other object. This is what
1075 you want most of the time, but it can lead to inconsistent results when
1076 you compare a number of DateTime objects, some of which are floating,
1077 and some of which are in other time zones.
1078 If you want to have consistent results (because you want to sort a
1080 number of objects, for example), you can use the
1081 "compare_ignore_floating()" method:
1082 @dates = sort { DateTime->compare_ignore_floating($a, $b) } @dates;
1084 In this case, objects with a floating time zone will be sorted as if
1086 they were UTC times.
1087 Since DateTime objects overload comparison operators, this:
1089 @dates = sort @dates;
1091 is equivalent to this:
1093 @dates = sort { DateTime->compare($a, $b) } @dates;
1095 DateTime objects can be compared to any other calendar class that
1097 implements the "utc_rd_values()" method.
1098 Testing Code That Uses DateTime
1100 If you are trying to test code that calls uses DateTime, you may want
1101 to be able to explicitly set the value returned by Perl's "time()"
1102 builtin. This builtin is called by "DateTime->now()" and
1103 "DateTime->today()".
1104 You can override "CORE::GLOBAL::time()", but this will only work if
1106 you do this before loading DateTime. If doing this is inconvenient,
1107 you can also override "DateTime::_core_time()":
1108 no warnings 'redefine';
1110 local *DateTime::_core_time = sub { return 42 };
1111 DateTime is guaranteed to call this subroutine to get the current
1113 "time()" value. You can also override the "_core_time()" sub in a
1114 subclass of DateTime and use that.
1115 How DateTime Math Works
1117 It's important to have some understanding of how datetime math is
1118 implemented in order to effectively use this module and
1119 "DateTime::Duration".
1120 Making Things Simple
1122 If you want to simplify your life and not have to think too hard about
1124 the nitty-gritty of datetime math, I have several recommendations:
1125 · use the floating time zone
1127 If you do not care about time zones or leap seconds, use the
1129 "floating" timezone:
1130 my $dt = DateTime->now( time_zone => 'floating' );
1132 Math done on two objects in the floating time zone produces very
1134 predictable results.
1135 Note that in most cases you will want to start by creating an
1137 object in a specific zone and then convert it to the floating time
1138 zone. When an object goes from a real zone to the floating zone,
1139 the time for the object remains the same.
1140 This means that passing the floating zone to a constructor may not
1142 do what you want.
1143 my $dt = DateTime->now( time_zone => 'floating' );
1145 is equivalent to
1147 my $dt = DateTime->now( time_zone => 'UTC' )->set_time_zone('floating');
1149 This might not be what you wanted. Instead, you may prefer to do
1151 this:
1152 my $dt = DateTime->now( time_zone => 'local' )->set_time_zone('floating');
1154 · use UTC for all calculations
1156 If you do care about time zones (particularly DST) or leap seconds,
1158 try to use non-UTC time zones for presentation and user input only.
1159 Convert to UTC immediately and convert back to the local time zone
1160 for presentation:
1161 my $dt = DateTime->new( %user_input, time_zone => $user_tz );
1163 $dt->set_time_zone('UTC');
1164 # do various operations - store it, retrieve it, add, subtract, etc.
1166 $dt->set_time_zone($user_tz);
1168 print $dt->datetime;
1169 · math on non-UTC time zones
1171 If you need to do date math on objects with non-UTC time zones,
1173 please read the caveats below carefully. The results "DateTime.pm"
1174 produces are predictable and correct, and mostly intuitive, but
1175 datetime math gets very ugly when time zones are involved, and
1176 there are a few strange corner cases involving subtraction of two
1177 datetimes across a DST change.
1178 If you can always use the floating or UTC time zones, you can skip
1180 ahead to "Leap Seconds and Date Math"
1181 · date vs datetime math
1183 If you only care about the date (calendar) portion of a datetime,
1185 you should use either "delta_md()" or "delta_days()", not
1186 "subtract_datetime()". This will give predictable, unsurprising
1187 results, free from DST-related complications.
1188 · subtract_datetime() and add_duration()
1190 You must convert your datetime objects to the UTC time zone before
1192 doing date math if you want to make sure that the following
1193 formulas are always true:
1194 $dt2 - $dt1 = $dur
1196 $dt1 + $dur = $dt2
1197 $dt2 - $dur = $dt1
1198 Note that using "delta_days" ensures that this formula always
1200 works, regardless of the timezone of the objects involved, as does
1201 using "subtract_datetime_absolute()". Other methods of subtraction
1202 are not always reversible.
1203 · never do math on two objects where only one is in the floating time
1205 zone
1206 The date math code accounts for leap seconds whenever the
1208 "DateTime" object is not in the floating time zone. If you try to
1209 do math where one object is in the floating zone and the other
1210 isn't, the results will be confusing and wrong.
1211 Adding a Duration to a DateTime
1213 The parts of a duration can be broken down into five parts. These are
1215 months, days, minutes, seconds, and nanoseconds. Adding one month to a
1216 date is different than adding 4 weeks or 28, 29, 30, or 31 days.
1217 Similarly, due to DST and leap seconds, adding a day can be different
1218 than adding 86,400 seconds, and adding a minute is not exactly the same
1219 as 60 seconds.
1220 We cannot convert between these units, except for seconds and
1222 nanoseconds, because there is no fixed conversion between the two
1223 units, because of things like leap seconds, DST changes, etc.
1224 "DateTime.pm" always adds (or subtracts) days, then months, minutes,
1226 and then seconds and nanoseconds. If there are any boundary overflows,
1227 these are normalized at each step. For the days and months the local
1228 (not UTC) values are used. For minutes and seconds, the local values
1229 are used. This generally just works.
1230 This means that adding one month and one day to February 28, 2003 will
1232 produce the date April 1, 2003, not March 29, 2003.
1233 my $dt = DateTime->new( year => 2003, month => 2, day => 28 );
1235 $dt->add( months => 1, days => 1 );
1237 # 2003-04-01 - the result
1239 On the other hand, if we add months first, and then separately add
1241 days, we end up with March 29, 2003:
1242 $dt->add( months => 1 )->add( days => 1 );
1244 # 2003-03-29
1246 We see similar strangeness when math crosses a DST boundary:
1248 my $dt = DateTime->new(
1250 year => 2003,
1251 month => 4,
1252 day => 5,
1253 hour => 1,
1254 minute => 58,
1255 time_zone => "America/Chicago",
1256 );
1257 $dt->add( days => 1, minutes => 3 );
1259 # 2003-04-06 02:01:00
1260 $dt->add( minutes => 3 )->add( days => 1 );
1262 # 2003-04-06 03:01:00
1263 Note that if you converted the datetime object to UTC first you would
1265 get predictable results.
1266 If you want to know how many seconds a duration object represents, you
1268 have to add it to a datetime to find out, so you could do:
1269 my $now = DateTime->now( time_zone => 'UTC' );
1271 my $later = $now->clone->add_duration($duration);
1272 my $seconds_dur = $later->subtract_datetime_absolute($now);
1274 This returns a duration which only contains seconds and nanoseconds.
1276 If we were add the duration to a different datetime object we might get
1278 a different number of seconds.
1279 DateTime::Duration supports three different end-of-month algorithms for
1281 adding months. This comes into play when an addition results in a day
1282 past the end of the month (for example, adding one month to January
1283 30).
1284 # 2010-08-31 + 1 month = 2010-10-01
1286 $dt->add( months => 1, end_of_month => 'wrap' );
1287 # 2010-01-30 + 1 month = 2010-02-28
1289 $dt->add( months => 1, end_of_month => 'limit' );
1290 # 2010-04-30 + 1 month = 2010-05-31
1292 $dt->add( months => 1, end_of_month => 'preserve' );
1293 By default, it uses "wrap" for positive durations and "preserve" for
1295 negative durations. See DateTime::Duration for a detailed explanation
1296 of these algorithms.
1297 If you need to do lots of work with durations, take a look at Rick
1299 Measham's "DateTime::Format::Duration" module, which lets you present
1300 information from durations in many useful ways.
1301 There are other subtract/delta methods in DateTime.pm to generate
1303 different types of durations. These methods are "subtract_datetime()",
1304 "subtract_datetime_absolute()", "delta_md()", "delta_days()", and
1305 "delta_ms()".
1306 DateTime Subtraction
1308 Date subtraction is done solely based on the two object's local
1310 datetimes, with one exception to handle DST changes. Also, if the two
1311 datetime objects are in different time zones, one of them is converted
1312 to the other's time zone first before subtraction. This is best
1313 explained through examples:
1314 The first of these probably makes the most sense:
1316 my $dt1 = DateTime->new(
1318 year => 2003,
1319 month => 5,
1320 day => 6,
1321 time_zone => 'America/Chicago',
1322 );
1323 # not DST
1325 my $dt2 = DateTime->new(
1327 year => 2003,
1328 month => 11,
1329 day => 6,
1330 time_zone => 'America/Chicago',
1331 );
1332 # is DST
1334 my $dur = $dt2->subtract_datetime($dt1);
1336 # 6 months
1337 Nice and simple.
1339 This one is a little trickier, but still fairly logical:
1341 my $dt1 = DateTime->new(
1343 year => 2003,
1344 month => 4,
1345 day => 5,
1346 hour => 1,
1347 minute => 58,
1348 time_zone => "America/Chicago",
1349 );
1350 # is DST
1352 my $dt2 = DateTime->new(
1354 year => 2003,
1355 month => 4,
1356 day => 7,
1357 hour => 2,
1358 minute => 1,
1359 time_zone => "America/Chicago",
1360 );
1361 # not DST
1363 my $dur = $dt2->subtract_datetime($dt1);
1365 # 2 days and 3 minutes
1367 Which contradicts the result this one gives, even though they both make
1369 sense:
1370 my $dt1 = DateTime->new(
1372 year => 2003,
1373 month => 4,
1374 day => 5,
1375 hour => 1,
1376 minute => 58,
1377 time_zone => "America/Chicago",
1378 );
1379 # is DST
1381 my $dt2 = DateTime->new(
1383 year => 2003,
1384 month => 4,
1385 day => 6,
1386 hour => 3,
1387 minute => 1,
1388 time_zone => "America/Chicago",
1389 );
1390 # not DST
1392 my $dur = $dt2->subtract_datetime($dt1);
1394 # 1 day and 3 minutes
1396 This last example illustrates the "DST" exception mentioned earlier.
1398 The exception accounts for the fact 2003-04-06 only lasts 23 hours.
1399 And finally:
1401 my $dt2 = DateTime->new(
1403 year => 2003,
1404 month => 10,
1405 day => 26,
1406 hour => 1,
1407 time_zone => 'America/Chicago',
1408 );
1409 my $dt1 = $dt2->clone->subtract( hours => 1 );
1411 my $dur = $dt2->subtract_datetime($dt1);
1413 # 60 minutes
1414 This seems obvious until you realize that subtracting 60 minutes from
1416 $dt2 in the above example still leaves the clock time at "01:00:00".
1417 This time we are accounting for a 25 hour day.
1418 Reversibility
1420 Date math operations are not always reversible. This is because of the
1422 way that addition operations are ordered. As was discussed earlier,
1423 adding 1 day and 3 minutes in one call to "add()" is not the same as
1424 first adding 3 minutes and 1 day in two separate calls.
1425 If we take a duration returned from "subtract_datetime()" and then try
1427 to add or subtract that duration from one of the datetimes we just
1428 used, we sometimes get interesting results:
1429 my $dt1 = DateTime->new(
1431 year => 2003,
1432 month => 4,
1433 day => 5,
1434 hour => 1,
1435 minute => 58,
1436 time_zone => "America/Chicago",
1437 );
1438 my $dt2 = DateTime->new(
1440 year => 2003,
1441 month => 4,
1442 day => 6,
1443 hour => 3,
1444 minute => 1,
1445 time_zone => "America/Chicago",
1446 );
1447 my $dur = $dt2->subtract_datetime($dt1);
1449 # 1 day and 3 minutes
1450 $dt1->add_duration($dur);
1452 # gives us $dt2
1453 $dt2->subtract_duration($dur);
1455 # gives us 2003-04-05 02:58:00 - 1 hour later than $dt1
1456 The "subtract_duration()" operation gives us a (perhaps) unexpected
1458 answer because it first subtracts one day to get 2003-04-05T03:01:00
1459 and then subtracts 3 minutes to get the final result.
1460 If we explicitly reverse the order we can get the original value of
1462 $dt1. This can be facilitated by "DateTime::Duration"'s
1463 "calendar_duration()" and "clock_duration()" methods:
1464 $dt2->subtract_duration( $dur->clock_duration )
1466 ->subtract_duration( $dur->calendar_duration );
1467 Leap Seconds and Date Math
1469 The presence of leap seconds can cause even more anomalies in date
1471 math. For example, the following is a legal datetime:
1472 my $dt = DateTime->new(
1474 year => 1972,
1475 month => 12,
1476 day => 31,
1477 hour => 23,
1478 minute => 59,
1479 second => 60,
1480 time_zone => 'UTC'
1481 );
1482 If we do the following:
1484 $dt->add( months => 1 );
1486 Then the datetime is now "1973-02-01 00:00:00", because there is no
1488 23:59:60 on 1973-01-31.
1489 Leap seconds also force us to distinguish between minutes and seconds
1491 during date math. Given the following datetime:
1492 my $dt = DateTime->new(
1494 year => 1972,
1495 month => 12,
1496 day => 31,
1497 hour => 23,
1498 minute => 59,
1499 second => 30,
1500 time_zone => 'UTC'
1501 );
1502 we will get different results when adding 1 minute than we get if we
1504 add 60 seconds. This is because in this case, the last minute of the
1505 day, beginning at 23:59:00, actually contains 61 seconds.
1506 Here are the results we get:
1508 # 1972-12-31 23:59:30 - our starting datetime
1510 $dt->clone->add( minutes => 1 );
1512 # 1973-01-01 00:00:30 - one minute later
1513 $dt->clone->add( seconds => 60 );
1515 # 1973-01-01 00:00:29 - 60 seconds later
1516 $dt->clone->add( seconds => 61 );
1518 # 1973-01-01 00:00:30 - 61 seconds later
1519 Local vs. UTC and 24 hours vs. 1 day
1521 When math crosses a daylight saving boundary, a single day may have
1523 more or less than 24 hours.
1524 For example, if you do this:
1526 my $dt = DateTime->new(
1528 year => 2003,
1529 month => 4,
1530 day => 5,
1531 hour => 2,
1532 time_zone => 'America/Chicago',
1533 );
1534 $dt->add( days => 1 );
1536 then you will produce an invalid local time, and therefore an exception
1538 will be thrown.
1539 However, this works:
1541 my $dt = DateTime->new(
1543 year => 2003,
1544 month => 4,
1545 day => 5,
1546 hour => 2,
1547 time_zone => 'America/Chicago',
1548 );
1549 $dt->add( hours => 24 );
1551 and produces a datetime with the local time of "03:00".
1553 If all this makes your head hurt, there is a simple alternative. Just
1555 convert your datetime object to the "UTC" time zone before doing date
1556 math on it, and switch it back to the local time zone afterwards. This
1557 avoids the possibility of having date math throw an exception, and
1558 makes sure that 1 day equals 24 hours. Of course, this may not always
1559 be desirable, so caveat user!
1560 Overloading
1562 This module explicitly overloads the addition (+), subtraction (-),
1563 string and numeric comparison operators. This means that the following
1564 all do sensible things:
1565 my $new_dt = $dt + $duration_obj;
1567 my $new_dt = $dt - $duration_obj;
1569 my $duration_obj = $dt - $new_dt;
1571 foreach my $dt ( sort @dts ) { ... }
1573 Additionally, the fallback parameter is set to true, so other derivable
1575 operators (+=, -=, etc.) will work properly. Do not expect increment
1576 (++) or decrement (--) to do anything useful.
1577 The string comparison operators, "eq" or "ne", will use the string
1579 value to compare with non-DateTime objects.
1580 DateTime objects do not have a numeric value, using "==" or "<=>" to
1582 compare a DateTime object with a non-DateTime object will result in an
1583 exception. To safely sort mixed DateTime and non-DateTime objects, use
1584 "sort { $a cmp $b } @dates".
1585 The module also overloads stringification using the object's formatter,
1587 defaulting to "iso8601()" method. See "Formatters And Stringification"
1588 for details.
1589 Formatters And Stringification
1591 You can optionally specify a "formatter", which is usually a
1592 DateTime::Format::* object/class, to control the stringification of the
1593 DateTime object.
1594 Any of the constructor methods can accept a formatter argument:
1596 my $formatter = DateTime::Format::Strptime->new(...);
1598 my $dt = DateTime->new(year => 2004, formatter => $formatter);
1599 Or, you can set it afterwards:
1601 $dt->set_formatter($formatter);
1603 $formatter = $dt->formatter();
1604 Once you set the formatter, the overloaded stringification method will
1606 use the formatter. If unspecified, the "iso8601()" method is used.
1607 A formatter can be handy when you know that in your application you
1609 want to stringify your DateTime objects into a special format all the
1610 time, for example to a different language.
1611 If you provide a formatter class name or object, it must implement a
1613 "format_datetime" method. This method will be called with just the
1614 DateTime object as its argument.
1615 CLDR Patterns
1617 The CLDR pattern language is both more powerful and more complex than
1618 strftime. Unlike strftime patterns, you often have to explicitly escape
1619 text that you do not want formatted, as the patterns are simply letters
1620 without any prefix.
1621 For example, "yyyy-MM-dd" is a valid CLDR pattern. If you want to
1623 include any lower or upper case ASCII characters as-is, you can
1624 surround them with single quotes ('). If you want to include a single
1625 quote, you must escape it as two single quotes ('').
1626 'Today is ' EEEE
1628 'It is now' h 'o''clock' a
1629 Spaces and any non-letter text will always be passed through as-is.
1631 Many CLDR patterns which produce numbers will pad the number with
1633 leading zeroes depending on the length of the format specifier. For
1634 example, "h" represents the current hour from 1-12. If you specify "hh"
1635 then the 1-9 will have a leading zero prepended.
1636 However, CLDR often uses five of a letter to represent the narrow form
1638 of a pattern. This inconsistency is necessary for backwards
1639 compatibility.
1640 CLDR often distinguishes between the "format" and "stand-alone" forms
1642 of a pattern. The format pattern is used when the thing in question is
1643 being placed into a larger string. The stand-alone form is used when
1644 displaying that item by itself, for example in a calendar.
1645 It also often provides three sizes for each item, wide (the full name),
1647 abbreviated, and narrow. The narrow form is often just a single
1648 character, for example "T" for "Tuesday", and may not be unique.
1649 CLDR provides a fairly complex system for localizing time zones that we
1651 ignore entirely. The time zone patterns just use the information
1652 provided by "DateTime::TimeZone", and do not follow the CLDR spec.
1653 The output of a CLDR pattern is always localized, when applicable.
1655 CLDR provides the following patterns:
1657 · G{1,3}
1659 The abbreviated era (BC, AD).
1661 · GGGG
1663 The wide era (Before Christ, Anno Domini).
1665 · GGGGG
1667 The narrow era, if it exists (and it mostly doesn't).
1669 · y and y{3,}
1671 The year, zero-prefixed as needed. Negative years will start with a
1673 "-", and this will be included in the length calculation.
1674 In other, words the "yyyyy" pattern will format year -1234 as
1676 "-1234", not "-01234".
1677 · yy
1679 This is a special case. It always produces a two-digit year, so
1681 "1976" becomes "76". Negative years will start with a "-", making
1682 them one character longer.
1683 · Y{1,}
1685 The year in "week of the year" calendars, from "$dt->week_year()".
1687 · u{1,}
1689 Same as "y" except that "uu" is not a special case.
1691 · Q{1,2}
1693 The quarter as a number (1..4).
1695 · QQQ
1697 The abbreviated format form for the quarter.
1699 · QQQQ
1701 The wide format form for the quarter.
1703 · q{1,2}
1705 The quarter as a number (1..4).
1707 · qqq
1709 The abbreviated stand-alone form for the quarter.
1711 · qqqq
1713 The wide stand-alone form for the quarter.
1715 · M{1,2]
1717 The numerical month.
1719 · MMM
1721 The abbreviated format form for the month.
1723 · MMMM
1725 The wide format form for the month.
1727 · MMMMM
1729 The narrow format form for the month.
1731 · L{1,2]
1733 The numerical month.
1735 · LLL
1737 The abbreviated stand-alone form for the month.
1739 · LLLL
1741 The wide stand-alone form for the month.
1743 · LLLLL
1745 The narrow stand-alone form for the month.
1747 · w{1,2}
1749 The week of the year, from "$dt->week_number()".
1751 · W
1753 The week of the month, from "$dt->week_of_month()".
1755 · d{1,2}
1757 The numeric day of the month.
1759 · D{1,3}
1761 The numeric day of the year.
1763 · F
1765 The day of the week in the month, from "$dt->weekday_of_month()".
1767 · g{1,}
1769 The modified Julian day, from "$dt->mjd()".
1771 · E{1,3} and eee
1773 The abbreviated format form for the day of the week.
1775 · EEEE and eeee
1777 The wide format form for the day of the week.
1779 · EEEEE and eeeee
1781 The narrow format form for the day of the week.
1783 · e{1,2}
1785 The local numeric day of the week, from 1 to 7. This number depends
1787 on what day is considered the first day of the week, which varies
1788 by locale. For example, in the US, Sunday is the first day of the
1789 week, so this returns 2 for Monday.
1790 · c
1792 The numeric day of the week from 1 to 7, treating Monday as the
1794 first of the week, regardless of locale.
1795 · ccc
1797 The abbreviated stand-alone form for the day of the week.
1799 · cccc
1801 The wide stand-alone form for the day of the week.
1803 · ccccc
1805 The narrow format form for the day of the week.
1807 · a
1809 The localized form of AM or PM for the time.
1811 · h{1,2}
1813 The hour from 1-12.
1815 · H{1,2}
1817 The hour from 0-23.
1819 · K{1,2}
1821 The hour from 0-11.
1823 · k{1,2}
1825 The hour from 1-24.
1827 · j{1,2}
1829 The hour, in 12 or 24 hour form, based on the preferred form for
1831 the locale. In other words, this is equivalent to either "h{1,2}"
1832 or "H{1,2}".
1833 · m{1,2}
1835 The minute.
1837 · s{1,2}
1839 The second.
1841 · S{1,}
1843 The fractional portion of the seconds, rounded based on the length
1845 of the specifier. This returned without a leading decimal point,
1846 but may have leading or trailing zeroes.
1847 · A{1,}
1849 The millisecond of the day, based on the current time. In other
1851 words, if it is 12:00:00.00, this returns 43200000.
1852 · z{1,3}
1854 The time zone short name.
1856 · zzzz
1858 The time zone long name.
1860 · Z{1,3}
1862 The time zone offset.
1864 · ZZZZ
1866 The time zone short name and the offset as one string, so something
1868 like "CDT-0500".
1869 · ZZZZZ
1871 The time zone offset as a sexagesimal number, so something like
1873 "-05:00". (This is useful for W3C format.)
1874 · v{1,3}
1876 The time zone short name.
1878 · vvvv
1880 The time zone long name.
1882 · V{1,3}
1884 The time zone short name.
1886 · VVVV
1888 The time zone long name.
1890 CLDR "Available Formats"
1892 The CLDR data includes pre-defined formats for various patterns such as
1894 "month and day" or "time of day". Using these formats lets you render
1895 information about a datetime in the most natural way for users from a
1896 given locale.
1897 These formats are indexed by a key that is itself a CLDR pattern. When
1899 you look these up, you get back a different CLDR pattern suitable for
1900 the locale.
1901 Let's look at some example We'll use "2008-02-05T18:30:30" as our
1903 example datetime value, and see how this is rendered for the "en-US"
1904 and "fr-FR" locales.
1905 · "MMMd"
1907 The abbreviated month and day as number. For "en-US", we get the
1909 pattern "MMM d", which renders as "Feb 5". For "fr-FR", we get the
1910 pattern "d MMM", which renders as "5 févr.".
1911 · "yQQQ"
1913 The year and abbreviated quarter of year. For "en-US", we get the
1915 pattern "QQQ y", which renders as "Q1 2008". For "fr-FR", we get
1916 the same pattern, "QQQ y", which renders as "T1 2008".
1917 · "hm"
1919 The 12-hour time of day without seconds. For "en-US", we get the
1921 pattern "h:mm a", which renders as "6:30 PM". For "fr-FR", we get
1922 the exact same pattern and rendering.
1923 The available formats for each locale are documented in the POD for
1925 that locale. To get back the format, you use the "$locale->format_for"
1926 method. For example:
1927 say $dt->format_cldr( $dt->locale->format_for('MMMd') );
1929 strftime Patterns
1931 The following patterns are allowed in the format string given to the
1932 "$dt->strftime()" method:
1933 · %a
1935 The abbreviated weekday name.
1937 · %A
1939 The full weekday name.
1941 · %b
1943 The abbreviated month name.
1945 · %B
1947 The full month name.
1949 · %c
1951 The default datetime format for the object's locale.
1953 · %C
1955 The century number (year/100) as a 2-digit integer.
1957 · %d
1959 The day of the month as a decimal number (range 01 to 31).
1961 · %D
1963 Equivalent to %m/%d/%y. This is not a good standard format if you
1965 want folks from both the United States and the rest of the world to
1966 understand the date!
1967 · %e
1969 Like %d, the day of the month as a decimal number, but a leading
1971 zero is replaced by a space.
1972 · %F
1974 Equivalent to %Y-%m-%d (the ISO 8601 date format)
1976 · %G
1978 The ISO 8601 year with century as a decimal number. The 4-digit
1980 year corresponding to the ISO week number (see %V). This has the
1981 same format and value as %Y, except that if the ISO week number
1982 belongs to the previous or next year, that year is used instead.
1983 (TZ)
1984 · %g
1986 Like %G, but without century, i.e., with a 2-digit year (00-99).
1988 · %h
1990 Equivalent to %b.
1992 · %H
1994 The hour as a decimal number using a 24-hour clock (range 00 to
1996 23).
1997 · %I
1999 The hour as a decimal number using a 12-hour clock (range 01 to
2001 12).
2002 · %j
2004 The day of the year as a decimal number (range 001 to 366).
2006 · %k
2008 The hour (24-hour clock) as a decimal number (range 0 to 23);
2010 single digits are preceded by a blank. (See also %H.)
2011 · %l
2013 The hour (12-hour clock) as a decimal number (range 1 to 12);
2015 single digits are preceded by a blank. (See also %I.)
2016 · %m
2018 The month as a decimal number (range 01 to 12).
2020 · %M
2022 The minute as a decimal number (range 00 to 59).
2024 · %n
2026 A newline character.
2028 · %N
2030 The fractional seconds digits. Default is 9 digits (nanoseconds).
2032 %3N milliseconds (3 digits)
2034 %6N microseconds (6 digits)
2035 %9N nanoseconds (9 digits)
2036 This value will always be rounded down to the nearest integer.
2038 · %p
2040 Either `AM' or `PM' according to the given time value, or the
2042 corresponding strings for the current locale. Noon is treated as
2043 `pm' and midnight as `am'.
2044 · %P
2046 Like %p but in lowercase: `am' or `pm' or a corresponding string
2048 for the current locale.
2049 · %r
2051 The time in a.m. or p.m. notation. In the POSIX locale this is
2053 equivalent to `%I:%M:%S %p'.
2054 · %R
2056 The time in 24-hour notation (%H:%M). (SU) For a version including
2058 the seconds, see %T below.
2059 · %s
2061 The number of seconds since the epoch.
2063 · %S
2065 The second as a decimal number (range 00 to 61).
2067 · %t
2069 A tab character.
2071 · %T
2073 The time in 24-hour notation (%H:%M:%S).
2075 · %u
2077 The day of the week as a decimal, range 1 to 7, Monday being 1. See
2079 also %w.
2080 · %U
2082 The week number of the current year as a decimal number, range 00
2084 to 53, starting with the first Sunday as the first day of week 01.
2085 See also %V and %W.
2086 · %V
2088 The ISO 8601:1988 week number of the current year as a decimal
2090 number, range 01 to 53, where week 1 is the first week that has at
2091 least 4 days in the current year, and with Monday as the first day
2092 of the week. See also %U and %W.
2093 · %w
2095 The day of the week as a decimal, range 0 to 6, Sunday being 0. See
2097 also %u.
2098 · %W
2100 The week number of the current year as a decimal number, range 00
2102 to 53, starting with the first Monday as the first day of week 01.
2103 · %x
2105 The default date format for the object's locale.
2107 · %X
2109 The default time format for the object's locale.
2111 · %y
2113 The year as a decimal number without a century (range 00 to 99).
2115 · %Y
2117 The year as a decimal number including the century.
2119 · %z
2121 The time-zone as hour offset from UTC. Required to emit
2123 RFC822-conformant dates (using "%a, %d %b %Y %H:%M:%S %z").
2124 · %Z
2126 The short name for the time zone, typically an abbreviation like
2128 "EST" or "AEST".
2129 · %%
2131 A literal `%' character.
2133 · %{method}
2135 Any method name may be specified using the format "%{method}" name
2137 where "method" is a valid "DateTime.pm" object method.
2138 DateTime.pm and Storable
2140 DateTime implements Storable hooks in order to reduce the size of a
2141 serialized DateTime object.
2142
2144 This module is part of a larger ecosystem of modules in the DateTime
2145 family.
2146 DateTime::Set
2148 The DateTime::Set module represents sets (including recurrences) of
2149 datetimes. Many modules return sets or recurrences.
2150 Format Modules
2152 The various format modules exist to parse and format datetimes. For
2153 example, DateTime::Format::HTTP parses dates according to the RFC 1123
2154 format:
2155 my $datetime
2157 = DateTime::Format::HTTP->parse_datetime('Thu Feb 3 17:03:55 GMT 1994');
2158 print DateTime::Format::HTTP->format_datetime($datetime);
2160 Most format modules are suitable for use as a "formatter" with a
2162 DateTime object.
2163 All format modules start with "DateTime::Format::".
2165 Calendar Modules
2167 There are a number of modules on CPAN that implement non-Gregorian
2168 calendars, such as the Chinese, Mayan, and Julian calendars.
2169 All calendar modules start with "DateTime::Calendar::".
2171 Event Modules
2173 There are a number of modules that calculate the dates for events, such
2174 as Easter, Sunrise, etc.
2175 All event modules start with "DateTime::Event::".
2177 Others
2179 There are many other modules that work with DateTime, including modules
2180 in the "DateTimeX" namespace, as well as others.
2181 See the datetime wiki <http://datetime.perl.org> and search.cpan.org
2183 <http://search.cpan.org/search?query=datetime&mode=dist> for more
2184 details.
2185
2187 The tests in 20infinite.t seem to fail on some machines, particularly
2188 on Win32. This appears to be related to Perl's internal handling of
2189 IEEE infinity and NaN, and seems to be highly platform/compiler/phase
2190 of moon dependent.
2191 If you don't plan to use infinite datetimes you can probably ignore
2193 this. This will be fixed (perhaps) in future versions.
2194
2196 A Date with Perl <http://www.houseabsolute.com/presentations/a-date-
2197 with-perl/> - a talk I've given at a few YAPCs.
2198 datetime@perl.org mailing list
2200 <http://lists.perl.org/list/datetime.html>
2201 <http://datetime.perl.org/>
2203
2205 Bugs may be submitted at
2206 <https://github.com/houseabsolute/DateTime.pm/issues>.
2207 There is a mailing list available for users of this distribution,
2209 <mailto:datetime@perl.org>.
2210 I am also usually active on IRC as 'autarch' on "irc://irc.perl.org".
2212
2214 The source code repository for DateTime can be found at
2215 <https://github.com/houseabsolute/DateTime.pm>.
2216
2218 If you'd like to thank me for the work I've done on this module, please
2219 consider making a "donation" to me via PayPal. I spend a lot of free
2220 time creating free software, and would appreciate any support you'd
2221 care to offer.
2222 Please note that I am not suggesting that you must do this in order for
2224 me to continue working on this particular software. I will continue to
2225 do so, inasmuch as I have in the past, for as long as it interests me.
2226 Similarly, a donation made in this way will probably not make me work
2228 on this software much more, unless I get so many donations that I can
2229 consider working on free software full time (let's all have a chuckle
2230 at that together).
2231 To donate, log into PayPal and send money to autarch@urth.org, or use
2233 the button at <http://www.urth.org/~autarch/fs-donation.html>.
2234
2236 Dave Rolsky <autarch@urth.org>
2237
2239 · Ben Bennett <fiji@limey.net>
2240 · Christian Hansen <chansen@cpan.org>
2242 · Daisuke Maki <dmaki@cpan.org>
2244 · Dan Book <grinnz@gmail.com>
2246 · Dan Stewart <danielandrewstewart@gmail.com>
2248 · David E. Wheeler <david@justatheory.com>
2250 · David Precious <davidp@preshweb.co.uk>
2252 · Doug Bell <madcityzen@gmail.com>
2254 · Flávio Soibelmann Glock <fglock@gmail.com>
2256 · Gianni Ceccarelli <gianni.ceccarelli@broadbean.com>
2258 · Gregory Oschwald <oschwald@gmail.com>
2260 · Hauke D <haukex@zero-g.net>
2262 · Iain Truskett <deceased>
2264 · Jason McIntosh <jmac@jmac.org>
2266 · Joshua Hoblitt <jhoblitt@cpan.org>
2268 · Karen Etheridge <ether@cpan.org>
2270 · Mark Overmeer <mark@overmeer.net>
2272 · Michael Conrad <mike@nrdvana.net>
2274 · Michael R. Davis <mrdvt92@users.noreply.github.com>
2276 · Mohammad S Anwar <mohammad.anwar@yahoo.com>
2278 · M Somerville <dracos@users.noreply.github.com>
2280 · Nick Tonkin <1nickt@users.noreply.github.com>
2282 · Olaf Alders <olaf@wundersolutions.com>
2284 · Ovid <curtis_ovid_poe@yahoo.com>
2286 · Paul Howarth <paul@city-fan.org>
2288 · Philippe Bruhat (BooK) <book@cpan.org>
2290 · philip r brenan <philiprbrenan@gmail.com>
2292 · Ricardo Signes <rjbs@cpan.org>
2294 · Richard Bowen <bowen@cpan.org>
2296 · Ron Hill <rkhill@cpan.org>
2298 · Sam Kington <github@illuminated.co.uk>
2300 · viviparous <viviparous@prc>
2302
2304 This software is Copyright (c) 2003 - 2020 by Dave Rolsky.
2305 This is free software, licensed under:
2307 The Artistic License 2.0 (GPL Compatible)
2309 The full text of the license can be found in the LICENSE file included
2311 with this distribution.
2312perl v5.32.0 2020-07-28 DateTime(3)