1DateTime(3) User Contributed Perl Documentation DateTime(3)
2
6 DateTime - A date and time object for Perl
7
9 version 1.51
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 Return 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.
779 Since the epoch does not account for leap seconds, the epoch time for
781 1972-12-31T23:59:60 (UTC) is exactly the same as that for
782 1973-01-01T00:00:00.
783 $dt->hires_epoch()
785 Returns the epoch as a floating point number. The floating point
787 portion of the value represents the nanosecond value of the object.
788 This method is provided for compatibility with the "Time::HiRes"
789 module.
790 Note that this method suffers from the imprecision of floating point
792 numbers, and the result may end up rounded to an arbitrary degree
793 depending on your platform.
794 my $dt = DateTime->new( year => 2012, nanosecond => 4 );
796 say $dt->hires_epoch();
797 On my system, this simply prints 1325376000 because adding 0.000000004
799 to 1325376000 returns 1325376000.
800 $dt->is_finite(), $dt->is_infinite()
802 These methods allow you to distinguish normal datetime objects from
804 infinite ones. Infinite datetime objects are documented in
805 DateTime::Infinite.
806 $dt->utc_rd_values()
808 Returns the current UTC Rata Die days, seconds, and nanoseconds as a
810 three element list. This exists primarily to allow other calendar
811 modules to create objects based on the values provided by this object.
812 $dt->local_rd_values()
814 Returns the current local Rata Die days, seconds, and nanoseconds as a
816 three element list. This exists for the benefit of other modules which
817 might want to use this information for date math, such as
818 "DateTime::Event::Recurrence".
819 $dt->leap_seconds()
821 Returns the number of leap seconds that have happened up to the
823 datetime represented by the object. For floating datetimes, this always
824 returns 0.
825 $dt->utc_rd_as_seconds()
827 Returns the current UTC Rata Die days and seconds purely as seconds.
829 This number ignores any fractional seconds stored in the object, as
830 well as leap seconds.
831 $dt->locale()
833 Returns the current locale object.
835 $dt->formatter()
837 Returns current formatter object or class. See "Formatters And
839 Stringification" for details.
840 "Set" Methods
842 The remaining methods provided by "DateTime.pm", except where otherwise
843 specified, return the object itself, thus making method chaining
844 possible. For example:
845 my $dt = DateTime->now->set_time_zone( 'Australia/Sydney' );
847 my $first = DateTime
849 ->last_day_of_month( year => 2003, month => 3 )
850 ->add( days => 1 )
851 ->subtract( seconds => 1 );
852 $dt->set( .. )
854 This method can be used to change the local components of a date time.
856 This method accepts any parameter allowed by the "new()" method except
857 for "locale" or "time_zone". Use "set_locale()" and "set_time_zone()"
858 for those instead.
859 This method performs parameter validation just like the "new()" method.
861 Do not use this method to do date math. Use the "add()" and
863 "subtract()" methods instead.
864 $dt->set_year(), $dt->set_month(), etc.
866 DateTime has a "set_*" method for every item that can be passed to the
868 constructor:
869 · $dt->set_year()
871 · $dt->set_month()
873 · $dt->set_day()
875 · $dt->set_hour()
877 · $dt->set_minute()
879 · $dt->set_second()
881 · $dt->set_nanosecond()
883 These are shortcuts to calling "set()" with a single key. They all take
885 a single parameter.
886 $dt->truncate( to => ... )
888 This method allows you to reset some of the local time components in
890 the object to their "zero" values. The "to" parameter is used to
891 specify which values to truncate, and it may be one of "year",
892 "quarter", "month", "week", "local_week", "day", "hour", "minute", or
893 "second".
894 For example, if "month" is specified, then the local day becomes 1, and
896 the hour, minute, and second all become 0.
897 If "week" is given, then the datetime is set to the Monday of the week
899 in which it occurs, and the time components are all set to 0. If you
900 truncate to "local_week", then the first day of the week is locale-
901 dependent. For example, in the "en-US" locale, the first day of the
902 week is Sunday.
903 $dt->set_locale( $locale )
905 Sets the object's locale. You can provide either a locale code like
907 "en-US" or an object returned by "DateTime::Locale->load".
908 $dt->set_time_zone( $tz )
910 This method accepts either a time zone object or a string that can be
912 passed as the "name" parameter to "DateTime::TimeZone->new()". If the
913 new time zone's offset is different from the old time zone, then the
914 local time is adjusted accordingly.
915 For example:
917 my $dt = DateTime->new(
919 year => 2000,
920 month => 5,
921 day => 10,
922 hour => 15,
923 minute => 15,
924 time_zone => 'America/Los_Angeles',
925 );
926 print $dt->hour; # prints 15
928 $dt->set_time_zone( 'America/Chicago' );
930 print $dt->hour; # prints 17
932 If the old time zone was a floating time zone, then no adjustments to
934 the local time are made, except to account for leap seconds. If the new
935 time zone is floating, then the UTC time is adjusted in order to leave
936 the local time untouched.
937 Fans of Tsai Ming-Liang's films will be happy to know that this does
939 work:
940 my $dt = DateTime->now( time_zone => 'Asia/Taipei' );
942 $dt->set_time_zone( 'Europe/Paris' );
944 Yes, now we can know "ni3 na4 bian1 ji2dian3?"
946 $dt->set_formatter( $formatter )
948 Set the formatter for the object. See "Formatters And Stringification"
950 for details.
951 You can set this to "undef" to revert to the default formatter.
953 Math Methods
955 Like the set methods, math related methods always return the object
956 itself, to allow for chaining:
957 $dt->add( days => 1 )->subtract( seconds => 1 );
959 $dt->duration_class()
961 This returns "DateTime::Duration", but exists so that a subclass of
963 "DateTime.pm" can provide a different value.
964 $dt->add_duration( $duration_object )
966 This method adds a "DateTime::Duration" to the current datetime. See
968 the DateTime::Duration docs for more details.
969 $dt->add( parameters for DateTime::Duration )
971 This method is syntactic sugar around the "add_duration()" method. It
973 simply creates a new "DateTime::Duration" object using the parameters
974 given, and then calls the "add_duration()" method.
975 $dt->add( $duration_object )
977 A synonym of "$dt->add_duration( $duration_object )".
979 $dt->subtract_duration( $duration_object )
981 When given a "DateTime::Duration" object, this method simply calls
983 "invert()" on that object and passes that new duration to the
984 "add_duration" method.
985 $dt->subtract( DateTime::Duration->new parameters )
987 Like "add()", this is syntactic sugar for the "subtract_duration()"
989 method.
990 $dt->subtract( $duration_object )
992 A synonym of "$dt->subtract_duration( $duration_object )".
994 $dt->subtract_datetime( $datetime )
996 This method returns a new "DateTime::Duration" object representing the
998 difference between the two dates. The duration is relative to the
999 object from which $datetime is subtracted. For example:
1000 2003-03-15 00:00:00.00000000
1002 - 2003-02-15 00:00:00.00000000
1003 -------------------------------
1004 = 1 month
1005 Note that this duration is not an absolute measure of the amount of
1007 time between the two datetimes, because the length of a month varies,
1008 as well as due to the presence of leap seconds.
1009 The returned duration may have deltas for months, days, minutes,
1011 seconds, and nanoseconds.
1012 $dt->delta_md( $datetime )
1014 $dt->delta_days( $datetime )
1016 Each of these methods returns a new "DateTime::Duration" object
1018 representing some portion of the difference between two datetimes. The
1019 "delta_md()" method returns a duration which contains only the month
1020 and day portions of the duration is represented. The "delta_days()"
1021 method returns a duration which contains only days.
1022 The "delta_md" and "delta_days" methods truncate the duration so that
1024 any fractional portion of a day is ignored. Both of these methods
1025 operate on the date portion of a datetime only, and so effectively
1026 ignore the time zone.
1027 Unlike the subtraction methods, these methods always return a positive
1029 (or zero) duration.
1030 $dt->delta_ms( $datetime )
1032 Returns a duration which contains only minutes and seconds. Any day and
1034 month differences to minutes are converted to minutes and seconds. This
1035 method also always return a positive (or zero) duration.
1036 $dt->subtract_datetime_absolute( $datetime )
1038 This method returns a new "DateTime::Duration" object representing the
1040 difference between the two dates in seconds and nanoseconds. This is
1041 the only way to accurately measure the absolute amount of time between
1042 two datetimes, since units larger than a second do not represent a
1043 fixed number of seconds.
1044 Note that because of leap seconds, this may not return the same result
1046 as doing this math based on the value returned by "$dt->epoch()".
1047 Class Methods
1049 DateTime->DefaultLocale( $locale )
1050 This can be used to specify the default locale to be used when creating
1052 DateTime objects. If unset, then "en-US" is used.
1053 DateTime->compare( $dt1, $dt2 ), DateTime->compare_ignore_floating(
1055 $dt1, $dt2 )
1056 $cmp = DateTime->compare( $dt1, $dt2 );
1058 $cmp = DateTime->compare_ignore_floating( $dt1, $dt2 );
1060 Compare two DateTime objects. The semantics are compatible with Perl's
1062 "sort()" function; it returns -1 if $dt1 < $dt2, 0 if $dt1 == $dt2, 1
1063 if $dt1 > $dt2.
1064 If one of the two DateTime objects has a floating time zone, it will
1066 first be converted to the time zone of the other object. This is what
1067 you want most of the time, but it can lead to inconsistent results when
1068 you compare a number of DateTime objects, some of which are floating,
1069 and some of which are in other time zones.
1070 If you want to have consistent results (because you want to sort a
1072 number of objects, for example), you can use the
1073 "compare_ignore_floating()" method:
1074 @dates = sort { DateTime->compare_ignore_floating($a, $b) } @dates;
1076 In this case, objects with a floating time zone will be sorted as if
1078 they were UTC times.
1079 Since DateTime objects overload comparison operators, this:
1081 @dates = sort @dates;
1083 is equivalent to this:
1085 @dates = sort { DateTime->compare($a, $b) } @dates;
1087 DateTime objects can be compared to any other calendar class that
1089 implements the "utc_rd_values()" method.
1090 Testing Code That Uses DateTime
1092 If you are trying to test code that calls uses DateTime, you may want
1093 to be able to explicitly set the value returned by Perl's "time()"
1094 builtin. This builtin is called by "DateTime->now()" and
1095 "DateTime->today()".
1096 You can override "CORE::GLOBAL::time()", but this will only work if
1098 you do this before loading DateTime. If doing this is inconvenient,
1099 you can also override "DateTime::_core_time()":
1100 no warnings 'redefine';
1102 local *DateTime::_core_time = sub { return 42 };
1103 DateTime is guaranteed to call this subroutine to get the current
1105 "time()" value. You can also override the "_core_time()" sub in a
1106 subclass of DateTime and use that.
1107 How DateTime Math Works
1109 It's important to have some understanding of how datetime math is
1110 implemented in order to effectively use this module and
1111 "DateTime::Duration".
1112 Making Things Simple
1114 If you want to simplify your life and not have to think too hard about
1116 the nitty-gritty of datetime math, I have several recommendations:
1117 · use the floating time zone
1119 If you do not care about time zones or leap seconds, use the
1121 "floating" timezone:
1122 my $dt = DateTime->now( time_zone => 'floating' );
1124 Math done on two objects in the floating time zone produces very
1126 predictable results.
1127 Note that in most cases you will want to start by creating an
1129 object in a specific zone and then convert it to the floating time
1130 zone. When an object goes from a real zone to the floating zone,
1131 the time for the object remains the same.
1132 This means that passing the floating zone to a constructor may not
1134 do what you want.
1135 my $dt = DateTime->now( time_zone => 'floating' );
1137 is equivalent to
1139 my $dt = DateTime->now( time_zone => 'UTC' )->set_time_zone('floating');
1141 This might not be what you wanted. Instead, you may prefer to do
1143 this:
1144 my $dt = DateTime->now( time_zone => 'local' )->set_time_zone('floating');
1146 · use UTC for all calculations
1148 If you do care about time zones (particularly DST) or leap seconds,
1150 try to use non-UTC time zones for presentation and user input only.
1151 Convert to UTC immediately and convert back to the local time zone
1152 for presentation:
1153 my $dt = DateTime->new( %user_input, time_zone => $user_tz );
1155 $dt->set_time_zone('UTC');
1156 # do various operations - store it, retrieve it, add, subtract, etc.
1158 $dt->set_time_zone($user_tz);
1160 print $dt->datetime;
1161 · math on non-UTC time zones
1163 If you need to do date math on objects with non-UTC time zones,
1165 please read the caveats below carefully. The results "DateTime.pm"
1166 produces are predictable and correct, and mostly intuitive, but
1167 datetime math gets very ugly when time zones are involved, and
1168 there are a few strange corner cases involving subtraction of two
1169 datetimes across a DST change.
1170 If you can always use the floating or UTC time zones, you can skip
1172 ahead to "Leap Seconds and Date Math"
1173 · date vs datetime math
1175 If you only care about the date (calendar) portion of a datetime,
1177 you should use either "delta_md()" or "delta_days()", not
1178 "subtract_datetime()". This will give predictable, unsurprising
1179 results, free from DST-related complications.
1180 · subtract_datetime() and add_duration()
1182 You must convert your datetime objects to the UTC time zone before
1184 doing date math if you want to make sure that the following
1185 formulas are always true:
1186 $dt2 - $dt1 = $dur
1188 $dt1 + $dur = $dt2
1189 $dt2 - $dur = $dt1
1190 Note that using "delta_days" ensures that this formula always
1192 works, regardless of the timezone of the objects involved, as does
1193 using "subtract_datetime_absolute()". Other methods of subtraction
1194 are not always reversible.
1195 · never do math on two objects where only one is in the floating time
1197 zone
1198 The date math code accounts for leap seconds whenever the
1200 "DateTime" object is not in the floating time zone. If you try to
1201 do math where one object is in the floating zone and the other
1202 isn't, the results will be confusing and wrong.
1203 Adding a Duration to a Datetime
1205 The parts of a duration can be broken down into five parts. These are
1207 months, days, minutes, seconds, and nanoseconds. Adding one month to a
1208 date is different than adding 4 weeks or 28, 29, 30, or 31 days.
1209 Similarly, due to DST and leap seconds, adding a day can be different
1210 than adding 86,400 seconds, and adding a minute is not exactly the same
1211 as 60 seconds.
1212 We cannot convert between these units, except for seconds and
1214 nanoseconds, because there is no fixed conversion between the two
1215 units, because of things like leap seconds, DST changes, etc.
1216 "DateTime.pm" always adds (or subtracts) days, then months, minutes,
1218 and then seconds and nanoseconds. If there are any boundary overflows,
1219 these are normalized at each step. For the days and months the local
1220 (not UTC) values are used. For minutes and seconds, the local values
1221 are used. This generally just works.
1222 This means that adding one month and one day to February 28, 2003 will
1224 produce the date April 1, 2003, not March 29, 2003.
1225 my $dt = DateTime->new( year => 2003, month => 2, day => 28 );
1227 $dt->add( months => 1, days => 1 );
1229 # 2003-04-01 - the result
1231 On the other hand, if we add months first, and then separately add
1233 days, we end up with March 29, 2003:
1234 $dt->add( months => 1 )->add( days => 1 );
1236 # 2003-03-29
1238 We see similar strangeness when math crosses a DST boundary:
1240 my $dt = DateTime->new(
1242 year => 2003,
1243 month => 4,
1244 day => 5,
1245 hour => 1,
1246 minute => 58,
1247 time_zone => "America/Chicago",
1248 );
1249 $dt->add( days => 1, minutes => 3 );
1251 # 2003-04-06 02:01:00
1252 $dt->add( minutes => 3 )->add( days => 1 );
1254 # 2003-04-06 03:01:00
1255 Note that if you converted the datetime object to UTC first you would
1257 get predictable results.
1258 If you want to know how many seconds a duration object represents, you
1260 have to add it to a datetime to find out, so you could do:
1261 my $now = DateTime->now( time_zone => 'UTC' );
1263 my $later = $now->clone->add_duration($duration);
1264 my $seconds_dur = $later->subtract_datetime_absolute($now);
1266 This returns a duration which only contains seconds and nanoseconds.
1268 If we were add the duration to a different datetime object we might get
1270 a different number of seconds.
1271 DateTime::Duration supports three different end-of-month algorithms for
1273 adding months. This comes into play when an addition results in a day
1274 past the end of the month (for example, adding one month to January
1275 30).
1276 # 2010-08-31 + 1 month = 2010-10-01
1278 $dt->add( months => 1, end_of_month => 'wrap' );
1279 # 2010-01-30 + 1 month = 2010-02-28
1281 $dt->add( months => 1, end_of_month => 'limit' );
1282 # 2010-04-30 + 1 month = 2010-05-31
1284 $dt->add( months => 1, end_of_month => 'preserve' );
1285 By default, it uses "wrap" for positive durations and "preserve" for
1287 negative durations. See DateTime::Duration for a detailed explanation
1288 of these algorithms.
1289 If you need to do lots of work with durations, take a look at Rick
1291 Measham's "DateTime::Format::Duration" module, which lets you present
1292 information from durations in many useful ways.
1293 There are other subtract/delta methods in DateTime.pm to generate
1295 different types of durations. These methods are "subtract_datetime()",
1296 "subtract_datetime_absolute()", "delta_md()", "delta_days()", and
1297 "delta_ms()".
1298 Datetime Subtraction
1300 Date subtraction is done solely based on the two object's local
1302 datetimes, with one exception to handle DST changes. Also, if the two
1303 datetime objects are in different time zones, one of them is converted
1304 to the other's time zone first before subtraction. This is best
1305 explained through examples:
1306 The first of these probably makes the most sense:
1308 my $dt1 = DateTime->new(
1310 year => 2003,
1311 month => 5,
1312 day => 6,
1313 time_zone => 'America/Chicago',
1314 );
1315 # not DST
1317 my $dt2 = DateTime->new(
1319 year => 2003,
1320 month => 11,
1321 day => 6,
1322 time_zone => 'America/Chicago',
1323 );
1324 # is DST
1326 my $dur = $dt2->subtract_datetime($dt1);
1328 # 6 months
1329 Nice and simple.
1331 This one is a little trickier, but still fairly logical:
1333 my $dt1 = DateTime->new(
1335 year => 2003,
1336 month => 4,
1337 day => 5,
1338 hour => 1,
1339 minute => 58,
1340 time_zone => "America/Chicago",
1341 );
1342 # is DST
1344 my $dt2 = DateTime->new(
1346 year => 2003,
1347 month => 4,
1348 day => 7,
1349 hour => 2,
1350 minute => 1,
1351 time_zone => "America/Chicago",
1352 );
1353 # not DST
1355 my $dur = $dt2->subtract_datetime($dt1);
1357 # 2 days and 3 minutes
1359 Which contradicts the result this one gives, even though they both make
1361 sense:
1362 my $dt1 = DateTime->new(
1364 year => 2003,
1365 month => 4,
1366 day => 5,
1367 hour => 1,
1368 minute => 58,
1369 time_zone => "America/Chicago",
1370 );
1371 # is DST
1373 my $dt2 = DateTime->new(
1375 year => 2003,
1376 month => 4,
1377 day => 6,
1378 hour => 3,
1379 minute => 1,
1380 time_zone => "America/Chicago",
1381 );
1382 # not DST
1384 my $dur = $dt2->subtract_datetime($dt1);
1386 # 1 day and 3 minutes
1388 This last example illustrates the "DST" exception mentioned earlier.
1390 The exception accounts for the fact 2003-04-06 only lasts 23 hours.
1391 And finally:
1393 my $dt2 = DateTime->new(
1395 year => 2003,
1396 month => 10,
1397 day => 26,
1398 hour => 1,
1399 time_zone => 'America/Chicago',
1400 );
1401 my $dt1 = $dt2->clone->subtract( hours => 1 );
1403 my $dur = $dt2->subtract_datetime($dt1);
1405 # 60 minutes
1406 This seems obvious until you realize that subtracting 60 minutes from
1408 $dt2 in the above example still leaves the clock time at "01:00:00".
1409 This time we are accounting for a 25 hour day.
1410 Reversibility
1412 Date math operations are not always reversible. This is because of the
1414 way that addition operations are ordered. As was discussed earlier,
1415 adding 1 day and 3 minutes in one call to "add()" is not the same as
1416 first adding 3 minutes and 1 day in two separate calls.
1417 If we take a duration returned from "subtract_datetime()" and then try
1419 to add or subtract that duration from one of the datetimes we just
1420 used, we sometimes get interesting results:
1421 my $dt1 = DateTime->new(
1423 year => 2003,
1424 month => 4,
1425 day => 5,
1426 hour => 1,
1427 minute => 58,
1428 time_zone => "America/Chicago",
1429 );
1430 my $dt2 = DateTime->new(
1432 year => 2003,
1433 month => 4,
1434 day => 6,
1435 hour => 3,
1436 minute => 1,
1437 time_zone => "America/Chicago",
1438 );
1439 my $dur = $dt2->subtract_datetime($dt1);
1441 # 1 day and 3 minutes
1442 $dt1->add_duration($dur);
1444 # gives us $dt2
1445 $dt2->subtract_duration($dur);
1447 # gives us 2003-04-05 02:58:00 - 1 hour later than $dt1
1448 The "subtract_duration()" operation gives us a (perhaps) unexpected
1450 answer because it first subtracts one day to get 2003-04-05T03:01:00
1451 and then subtracts 3 minutes to get the final result.
1452 If we explicitly reverse the order we can get the original value of
1454 $dt1. This can be facilitated by "DateTime::Duration"'s
1455 "calendar_duration()" and "clock_duration()" methods:
1456 $dt2->subtract_duration( $dur->clock_duration )
1458 ->subtract_duration( $dur->calendar_duration );
1459 Leap Seconds and Date Math
1461 The presence of leap seconds can cause even more anomalies in date
1463 math. For example, the following is a legal datetime:
1464 my $dt = DateTime->new(
1466 year => 1972,
1467 month => 12,
1468 day => 31,
1469 hour => 23,
1470 minute => 59,
1471 second => 60,
1472 time_zone => 'UTC'
1473 );
1474 If we do the following:
1476 $dt->add( months => 1 );
1478 Then the datetime is now "1973-02-01 00:00:00", because there is no
1480 23:59:60 on 1973-01-31.
1481 Leap seconds also force us to distinguish between minutes and seconds
1483 during date math. Given the following datetime:
1484 my $dt = DateTime->new(
1486 year => 1972,
1487 month => 12,
1488 day => 31,
1489 hour => 23,
1490 minute => 59,
1491 second => 30,
1492 time_zone => 'UTC'
1493 );
1494 we will get different results when adding 1 minute than we get if we
1496 add 60 seconds. This is because in this case, the last minute of the
1497 day, beginning at 23:59:00, actually contains 61 seconds.
1498 Here are the results we get:
1500 # 1972-12-31 23:59:30 - our starting datetime
1502 $dt->clone->add( minutes => 1 );
1504 # 1973-01-01 00:00:30 - one minute later
1505 $dt->clone->add( seconds => 60 );
1507 # 1973-01-01 00:00:29 - 60 seconds later
1508 $dt->clone->add( seconds => 61 );
1510 # 1973-01-01 00:00:30 - 61 seconds later
1511 Local vs. UTC and 24 hours vs. 1 day
1513 When math crosses a daylight saving boundary, a single day may have
1515 more or less than 24 hours.
1516 For example, if you do this:
1518 my $dt = DateTime->new(
1520 year => 2003,
1521 month => 4,
1522 day => 5,
1523 hour => 2,
1524 time_zone => 'America/Chicago',
1525 );
1526 $dt->add( days => 1 );
1528 then you will produce an invalid local time, and therefore an exception
1530 will be thrown.
1531 However, this works:
1533 my $dt = DateTime->new(
1535 year => 2003,
1536 month => 4,
1537 day => 5,
1538 hour => 2,
1539 time_zone => 'America/Chicago',
1540 );
1541 $dt->add( hours => 24 );
1543 and produces a datetime with the local time of "03:00".
1545 If all this makes your head hurt, there is a simple alternative. Just
1547 convert your datetime object to the "UTC" time zone before doing date
1548 math on it, and switch it back to the local time zone afterwards. This
1549 avoids the possibility of having date math throw an exception, and
1550 makes sure that 1 day equals 24 hours. Of course, this may not always
1551 be desirable, so caveat user!
1552 Overloading
1554 This module explicitly overloads the addition (+), subtraction (-),
1555 string and numeric comparison operators. This means that the following
1556 all do sensible things:
1557 my $new_dt = $dt + $duration_obj;
1559 my $new_dt = $dt - $duration_obj;
1561 my $duration_obj = $dt - $new_dt;
1563 foreach my $dt ( sort @dts ) { ... }
1565 Additionally, the fallback parameter is set to true, so other derivable
1567 operators (+=, -=, etc.) will work properly. Do not expect increment
1568 (++) or decrement (--) to do anything useful.
1569 The string comparison operators, "eq" or "ne", will use the string
1571 value to compare with non-DateTime objects.
1572 DateTime objects do not have a numeric value, using "==" or "<=>" to
1574 compare a DateTime object with a non-DateTime object will result in an
1575 exception. To safely sort mixed DateTime and non-DateTime objects, use
1576 "sort { $a cmp $b } @dates".
1577 The module also overloads stringification using the object's formatter,
1579 defaulting to "iso8601()" method. See "Formatters And Stringification"
1580 for details.
1581 Formatters And Stringification
1583 You can optionally specify a "formatter", which is usually a
1584 DateTime::Format::* object/class, to control the stringification of the
1585 DateTime object.
1586 Any of the constructor methods can accept a formatter argument:
1588 my $formatter = DateTime::Format::Strptime->new(...);
1590 my $dt = DateTime->new(year => 2004, formatter => $formatter);
1591 Or, you can set it afterwards:
1593 $dt->set_formatter($formatter);
1595 $formatter = $dt->formatter();
1596 Once you set the formatter, the overloaded stringification method will
1598 use the formatter. If unspecified, the "iso8601()" method is used.
1599 A formatter can be handy when you know that in your application you
1601 want to stringify your DateTime objects into a special format all the
1602 time, for example to a different language.
1603 If you provide a formatter class name or object, it must implement a
1605 "format_datetime" method. This method will be called with just the
1606 DateTime object as its argument.
1607 CLDR Patterns
1609 The CLDR pattern language is both more powerful and more complex than
1610 strftime. Unlike strftime patterns, you often have to explicitly escape
1611 text that you do not want formatted, as the patterns are simply letters
1612 without any prefix.
1613 For example, "yyyy-MM-dd" is a valid CLDR pattern. If you want to
1615 include any lower or upper case ASCII characters as-is, you can
1616 surround them with single quotes ('). If you want to include a single
1617 quote, you must escape it as two single quotes ('').
1618 'Today is ' EEEE
1620 'It is now' h 'o''clock' a
1621 Spaces and any non-letter text will always be passed through as-is.
1623 Many CLDR patterns which produce numbers will pad the number with
1625 leading zeroes depending on the length of the format specifier. For
1626 example, "h" represents the current hour from 1-12. If you specify "hh"
1627 then the 1-9 will have a leading zero prepended.
1628 However, CLDR often uses five of a letter to represent the narrow form
1630 of a pattern. This inconsistency is necessary for backwards
1631 compatibility.
1632 CLDR often distinguishes between the "format" and "stand-alone" forms
1634 of a pattern. The format pattern is used when the thing in question is
1635 being placed into a larger string. The stand-alone form is used when
1636 displaying that item by itself, for example in a calendar.
1637 It also often provides three sizes for each item, wide (the full name),
1639 abbreviated, and narrow. The narrow form is often just a single
1640 character, for example "T" for "Tuesday", and may not be unique.
1641 CLDR provides a fairly complex system for localizing time zones that we
1643 ignore entirely. The time zone patterns just use the information
1644 provided by "DateTime::TimeZone", and do not follow the CLDR spec.
1645 The output of a CLDR pattern is always localized, when applicable.
1647 CLDR provides the following patterns:
1649 · G{1,3}
1651 The abbreviated era (BC, AD).
1653 · GGGG
1655 The wide era (Before Christ, Anno Domini).
1657 · GGGGG
1659 The narrow era, if it exists (and it mostly doesn't).
1661 · y and y{3,}
1663 The year, zero-prefixed as needed. Negative years will start with a
1665 "-", and this will be included in the length calculation.
1666 In other, words the "yyyyy" pattern will format year -1234 as
1668 "-1234", not "-01234".
1669 · yy
1671 This is a special case. It always produces a two-digit year, so
1673 "1976" becomes "76". Negative years will start with a "-", making
1674 them one character longer.
1675 · Y{1,}
1677 The year in "week of the year" calendars, from "$dt->week_year()".
1679 · u{1,}
1681 Same as "y" except that "uu" is not a special case.
1683 · Q{1,2}
1685 The quarter as a number (1..4).
1687 · QQQ
1689 The abbreviated format form for the quarter.
1691 · QQQQ
1693 The wide format form for the quarter.
1695 · q{1,2}
1697 The quarter as a number (1..4).
1699 · qqq
1701 The abbreviated stand-alone form for the quarter.
1703 · qqqq
1705 The wide stand-alone form for the quarter.
1707 · M{1,2]
1709 The numerical month.
1711 · MMM
1713 The abbreviated format form for the month.
1715 · MMMM
1717 The wide format form for the month.
1719 · MMMMM
1721 The narrow format form for the month.
1723 · L{1,2]
1725 The numerical month.
1727 · LLL
1729 The abbreviated stand-alone form for the month.
1731 · LLLL
1733 The wide stand-alone form for the month.
1735 · LLLLL
1737 The narrow stand-alone form for the month.
1739 · w{1,2}
1741 The week of the year, from "$dt->week_number()".
1743 · W
1745 The week of the month, from "$dt->week_of_month()".
1747 · d{1,2}
1749 The numeric day of the month.
1751 · D{1,3}
1753 The numeric day of the year.
1755 · F
1757 The day of the week in the month, from "$dt->weekday_of_month()".
1759 · g{1,}
1761 The modified Julian day, from "$dt->mjd()".
1763 · E{1,3} and eee
1765 The abbreviated format form for the day of the week.
1767 · EEEE and eeee
1769 The wide format form for the day of the week.
1771 · EEEEE and eeeee
1773 The narrow format form for the day of the week.
1775 · e{1,2}
1777 The local numeric day of the week, from 1 to 7. This number depends
1779 on what day is considered the first day of the week, which varies
1780 by locale. For example, in the US, Sunday is the first day of the
1781 week, so this returns 2 for Monday.
1782 · c
1784 The numeric day of the week from 1 to 7, treating Monday as the
1786 first of the week, regardless of locale.
1787 · ccc
1789 The abbreviated stand-alone form for the day of the week.
1791 · cccc
1793 The wide stand-alone form for the day of the week.
1795 · ccccc
1797 The narrow format form for the day of the week.
1799 · a
1801 The localized form of AM or PM for the time.
1803 · h{1,2}
1805 The hour from 1-12.
1807 · H{1,2}
1809 The hour from 0-23.
1811 · K{1,2}
1813 The hour from 0-11.
1815 · k{1,2}
1817 The hour from 1-24.
1819 · j{1,2}
1821 The hour, in 12 or 24 hour form, based on the preferred form for
1823 the locale. In other words, this is equivalent to either "h{1,2}"
1824 or "H{1,2}".
1825 · m{1,2}
1827 The minute.
1829 · s{1,2}
1831 The second.
1833 · S{1,}
1835 The fractional portion of the seconds, rounded based on the length
1837 of the specifier. This returned without a leading decimal point,
1838 but may have leading or trailing zeroes.
1839 · A{1,}
1841 The millisecond of the day, based on the current time. In other
1843 words, if it is 12:00:00.00, this returns 43200000.
1844 · z{1,3}
1846 The time zone short name.
1848 · zzzz
1850 The time zone long name.
1852 · Z{1,3}
1854 The time zone offset.
1856 · ZZZZ
1858 The time zone short name and the offset as one string, so something
1860 like "CDT-0500".
1861 · ZZZZZ
1863 The time zone offset as a sexagesimal number, so something like
1865 "-05:00". (This is useful for W3C format.)
1866 · v{1,3}
1868 The time zone short name.
1870 · vvvv
1872 The time zone long name.
1874 · V{1,3}
1876 The time zone short name.
1878 · VVVV
1880 The time zone long name.
1882 CLDR "Available Formats"
1884 The CLDR data includes pre-defined formats for various patterns such as
1886 "month and day" or "time of day". Using these formats lets you render
1887 information about a datetime in the most natural way for users from a
1888 given locale.
1889 These formats are indexed by a key that is itself a CLDR pattern. When
1891 you look these up, you get back a different CLDR pattern suitable for
1892 the locale.
1893 Let's look at some example We'll use "2008-02-05T18:30:30" as our
1895 example datetime value, and see how this is rendered for the "en-US"
1896 and "fr-FR" locales.
1897 · "MMMd"
1899 The abbreviated month and day as number. For "en-US", we get the
1901 pattern "MMM d", which renders as "Feb 5". For "fr-FR", we get the
1902 pattern "d MMM", which renders as "5 févr.".
1903 · "yQQQ"
1905 The year and abbreviated quarter of year. For "en-US", we get the
1907 pattern "QQQ y", which renders as "Q1 2008". For "fr-FR", we get
1908 the same pattern, "QQQ y", which renders as "T1 2008".
1909 · "hm"
1911 The 12-hour time of day without seconds. For "en-US", we get the
1913 pattern "h:mm a", which renders as "6:30 PM". For "fr-FR", we get
1914 the exact same pattern and rendering.
1915 The available formats for each locale are documented in the POD for
1917 that locale. To get back the format, you use the "$locale->format_for"
1918 method. For example:
1919 say $dt->format_cldr( $dt->locale->format_for('MMMd') );
1921 strftime Patterns
1923 The following patterns are allowed in the format string given to the
1924 "$dt->strftime()" method:
1925 · %a
1927 The abbreviated weekday name.
1929 · %A
1931 The full weekday name.
1933 · %b
1935 The abbreviated month name.
1937 · %B
1939 The full month name.
1941 · %c
1943 The default datetime format for the object's locale.
1945 · %C
1947 The century number (year/100) as a 2-digit integer.
1949 · %d
1951 The day of the month as a decimal number (range 01 to 31).
1953 · %D
1955 Equivalent to %m/%d/%y. This is not a good standard format if you
1957 want folks from both the United States and the rest of the world to
1958 understand the date!
1959 · %e
1961 Like %d, the day of the month as a decimal number, but a leading
1963 zero is replaced by a space.
1964 · %F
1966 Equivalent to %Y-%m-%d (the ISO 8601 date format)
1968 · %G
1970 The ISO 8601 year with century as a decimal number. The 4-digit
1972 year corresponding to the ISO week number (see %V). This has the
1973 same format and value as %Y, except that if the ISO week number
1974 belongs to the previous or next year, that year is used instead.
1975 (TZ)
1976 · %g
1978 Like %G, but without century, i.e., with a 2-digit year (00-99).
1980 · %h
1982 Equivalent to %b.
1984 · %H
1986 The hour as a decimal number using a 24-hour clock (range 00 to
1988 23).
1989 · %I
1991 The hour as a decimal number using a 12-hour clock (range 01 to
1993 12).
1994 · %j
1996 The day of the year as a decimal number (range 001 to 366).
1998 · %k
2000 The hour (24-hour clock) as a decimal number (range 0 to 23);
2002 single digits are preceded by a blank. (See also %H.)
2003 · %l
2005 The hour (12-hour clock) as a decimal number (range 1 to 12);
2007 single digits are preceded by a blank. (See also %I.)
2008 · %m
2010 The month as a decimal number (range 01 to 12).
2012 · %M
2014 The minute as a decimal number (range 00 to 59).
2016 · %n
2018 A newline character.
2020 · %N
2022 The fractional seconds digits. Default is 9 digits (nanoseconds).
2024 %3N milliseconds (3 digits)
2026 %6N microseconds (6 digits)
2027 %9N nanoseconds (9 digits)
2028 This value will always be rounded down to the nearest integer.
2030 · %p
2032 Either `AM' or `PM' according to the given time value, or the
2034 corresponding strings for the current locale. Noon is treated as
2035 `pm' and midnight as `am'.
2036 · %P
2038 Like %p but in lowercase: `am' or `pm' or a corresponding string
2040 for the current locale.
2041 · %r
2043 The time in a.m. or p.m. notation. In the POSIX locale this is
2045 equivalent to `%I:%M:%S %p'.
2046 · %R
2048 The time in 24-hour notation (%H:%M). (SU) For a version including
2050 the seconds, see %T below.
2051 · %s
2053 The number of seconds since the epoch.
2055 · %S
2057 The second as a decimal number (range 00 to 61).
2059 · %t
2061 A tab character.
2063 · %T
2065 The time in 24-hour notation (%H:%M:%S).
2067 · %u
2069 The day of the week as a decimal, range 1 to 7, Monday being 1. See
2071 also %w.
2072 · %U
2074 The week number of the current year as a decimal number, range 00
2076 to 53, starting with the first Sunday as the first day of week 01.
2077 See also %V and %W.
2078 · %V
2080 The ISO 8601:1988 week number of the current year as a decimal
2082 number, range 01 to 53, where week 1 is the first week that has at
2083 least 4 days in the current year, and with Monday as the first day
2084 of the week. See also %U and %W.
2085 · %w
2087 The day of the week as a decimal, range 0 to 6, Sunday being 0. See
2089 also %u.
2090 · %W
2092 The week number of the current year as a decimal number, range 00
2094 to 53, starting with the first Monday as the first day of week 01.
2095 · %x
2097 The default date format for the object's locale.
2099 · %X
2101 The default time format for the object's locale.
2103 · %y
2105 The year as a decimal number without a century (range 00 to 99).
2107 · %Y
2109 The year as a decimal number including the century.
2111 · %z
2113 The time-zone as hour offset from UTC. Required to emit
2115 RFC822-conformant dates (using "%a, %d %b %Y %H:%M:%S %z").
2116 · %Z
2118 The short name for the time zone, typically an abbreviation like
2120 "EST" or "AEST".
2121 · %%
2123 A literal `%' character.
2125 · %{method}
2127 Any method name may be specified using the format "%{method}" name
2129 where "method" is a valid "DateTime.pm" object method.
2130 DateTime.pm and Storable
2132 DateTime implements Storable hooks in order to reduce the size of a
2133 serialized DateTime object.
2134
2136 This module is part of a larger ecosystem of modules in the DateTime
2137 family.
2138 DateTime::Set
2140 The DateTime::Set module represents sets (including recurrences) of
2141 datetimes. Many modules return sets or recurrences.
2142 Format Modules
2144 The various format modules exist to parse and format datetimes. For
2145 example, DateTime::Format::HTTP parses dates according to the RFC 1123
2146 format:
2147 my $datetime
2149 = DateTime::Format::HTTP->parse_datetime('Thu Feb 3 17:03:55 GMT 1994');
2150 print DateTime::Format::HTTP->format_datetime($datetime);
2152 Most format modules are suitable for use as a "formatter" with a
2154 DateTime object.
2155 All format modules start with "DateTime::Format::".
2157 Calendar Modules
2159 There are a number of modules on CPAN that implement non-Gregorian
2160 calendars, such as the Chinese, Mayan, and Julian calendars.
2161 All calendar modules start with "DateTime::Calendar::".
2163 Event Modules
2165 There are a number of modules that calculate the dates for events, such
2166 as Easter, Sunrise, etc.
2167 All event modules start with "DateTime::Event::".
2169 Others
2171 There are many other modules that work with DateTime, including modules
2172 in the "DateTimeX" namespace, as well as others.
2173 See the datetime wiki <http://datetime.perl.org> and search.cpan.org
2175 <http://search.cpan.org/search?query=datetime&mode=dist> for more
2176 details.
2177
2179 The tests in 20infinite.t seem to fail on some machines, particularly
2180 on Win32. This appears to be related to Perl's internal handling of
2181 IEEE infinity and NaN, and seems to be highly platform/compiler/phase
2182 of moon dependent.
2183 If you don't plan to use infinite datetimes you can probably ignore
2185 this. This will be fixed (perhaps) in future versions.
2186
2188 A Date with Perl <http://www.houseabsolute.com/presentations/a-date-
2189 with-perl/> - a talk I've given at a few YAPCs.
2190 datetime@perl.org mailing list
2192 <http://lists.perl.org/list/datetime.html>
2193 <http://datetime.perl.org/>
2195
2197 Bugs may be submitted at
2198 <https://github.com/houseabsolute/DateTime.pm/issues>.
2199 There is a mailing list available for users of this distribution,
2201 <mailto:datetime@perl.org>.
2202 I am also usually active on IRC as 'autarch' on "irc://irc.perl.org".
2204
2206 The source code repository for DateTime can be found at
2207 <https://github.com/houseabsolute/DateTime.pm>.
2208
2210 If you'd like to thank me for the work I've done on this module, please
2211 consider making a "donation" to me via PayPal. I spend a lot of free
2212 time creating free software, and would appreciate any support you'd
2213 care to offer.
2214 Please note that I am not suggesting that you must do this in order for
2216 me to continue working on this particular software. I will continue to
2217 do so, inasmuch as I have in the past, for as long as it interests me.
2218 Similarly, a donation made in this way will probably not make me work
2220 on this software much more, unless I get so many donations that I can
2221 consider working on free software full time (let's all have a chuckle
2222 at that together).
2223 To donate, log into PayPal and send money to autarch@urth.org, or use
2225 the button at <http://www.urth.org/~autarch/fs-donation.html>.
2226
2228 Dave Rolsky <autarch@urth.org>
2229
2231 · Ben Bennett <fiji@limey.net>
2232 · Christian Hansen <chansen@cpan.org>
2234 · Daisuke Maki <dmaki@cpan.org>
2236 · Dan Book <grinnz@gmail.com>
2238 · Dan Stewart <danielandrewstewart@gmail.com>
2240 · David E. Wheeler <david@justatheory.com>
2242 · David Precious <davidp@preshweb.co.uk>
2244 · Doug Bell <madcityzen@gmail.com>
2246 · Flávio Soibelmann Glock <fglock@gmail.com>
2248 · Gianni Ceccarelli <gianni.ceccarelli@broadbean.com>
2250 · Gregory Oschwald <oschwald@gmail.com>
2252 · Hauke D <haukex@zero-g.net>
2254 · Iain Truskett <deceased>
2256 · Jason McIntosh <jmac@jmac.org>
2258 · Joshua Hoblitt <jhoblitt@cpan.org>
2260 · Karen Etheridge <ether@cpan.org>
2262 · Michael Conrad <mike@nrdvana.net>
2264 · Michael R. Davis <mrdvt92@users.noreply.github.com>
2266 · Mohammad S Anwar <mohammad.anwar@yahoo.com>
2268 · M Somerville <dracos@users.noreply.github.com>
2270 · Nick Tonkin <1nickt@users.noreply.github.com>
2272 · Olaf Alders <olaf@wundersolutions.com>
2274 · Ovid <curtis_ovid_poe@yahoo.com>
2276 · Paul Howarth <paul@city-fan.org>
2278 · Philippe Bruhat (BooK) <book@cpan.org>
2280 · Ricardo Signes <rjbs@cpan.org>
2282 · Richard Bowen <bowen@cpan.org>
2284 · Ron Hill <rkhill@cpan.org>
2286 · Sam Kington <github@illuminated.co.uk>
2288 · viviparous <viviparous@prc>
2290
2292 This software is Copyright (c) 2003 - 2019 by Dave Rolsky.
2293 This is free software, licensed under:
2295 The Artistic License 2.0 (GPL Compatible)
2297 The full text of the license can be found in the LICENSE file included
2299 with this distribution.
2300perl v5.30.0 2019-07-26 DateTime(3)