1DateTime(3) User Contributed Perl Documentation DateTime(3)
2
6 DateTime - A date and time object for Perl
7
9 version 1.54
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" module follows a simple logic for determining whether or
106 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 the
114 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", will
128 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 => $App::LocalTZ );
168 DateTime itself does not do this internally because local time zones
170 can change, and there's no good way to determine if it's changed
171 without doing all the work to look it up.
172 Far Future DST
174 Do not try to use named time zones (like "America/Chicago") with dates
175 very far in the future (thousands of years). The current implementation
176 of "DateTime::TimeZone" will use a huge amount of memory calculating
177 all the DST changes from now until the future date. Use UTC or the
178 floating time zone and you will be safe.
179 Globally Setting a Default Time Zone
181 Warning: This is very dangerous. Do this at your own risk!
182 By default, "DateTime" uses either the floating time zone or UTC for
184 newly created objects, depending on the constructor.
185 You can force "DateTime" to use a different time zone by setting the
187 "PERL_DATETIME_DEFAULT_TZ" environment variable.
188 As noted above, this is very dangerous, as it affects all code that
190 creates a "DateTime" object, including modules from CPAN. If those
191 modules expect the normal default, then setting this can cause
192 confusing breakage or subtly broken data. Before setting this variable,
193 you are strongly encouraged to audit your CPAN dependencies to see how
194 they use "DateTime". Try running the test suite for each dependency
195 with this environment variable set before using this in production.
196 Upper and Lower Bounds
198 Internally, dates are represented the number of days before or after
199 0001-01-01. This is stored as an integer, meaning that the upper and
200 lower bounds are based on your Perl's integer size ($Config{ivsize}).
201 The limit on 32-bit systems is around 2^29 days, which gets you to year
203 (+/-)1,469,903. On a 64-bit system you get 2^62 days, to year
204 (+/-)12,626,367,463,883,278 (12.626 quadrillion).
205
207 DateTime provides many methods. The documentation breaks them down into
208 groups based on what they do (constructor, accessors, modifiers, etc.).
209 Constructors
211 All constructors can die when invalid parameters are given.
212 Warnings
214 Currently, constructors will warn if you try to create a far future
216 DateTime (year >= 5000) with any time zone besides floating or UTC.
217 This can be very slow if the time zone has future DST transitions that
218 need to be calculated. If the date is sufficiently far in the future
219 this can be really slow (minutes).
220 All warnings from DateTime use the "DateTime" category and can be
222 suppressed with:
223 no warnings 'DateTime';
225 This warning may be removed in the future if DateTime::TimeZone is made
227 much faster.
228 DateTime->new( ... )
230 my $dt = DateTime->new(
232 year => 1966,
233 month => 10,
234 day => 25,
235 hour => 7,
236 minute => 15,
237 second => 47,
238 nanosecond => 500000000,
239 time_zone => 'America/Chicago',
240 );
241 This class method accepts the following parameters:
243 • year
245 An integer year for the DateTime. This can be any integer number
247 within the valid range for your system (See "Upper and Lower
248 Bounds"). This is required.
249 • month
251 An integer from 1-12. Defaults to 1.
253 • day
255 An integer from 1-31. The value will be validated based on the
257 month, to prevent creating invalid dates like February 30. Defaults
258 to 1.
259 • hour
261 An integer from 0-23. Hour 0 is midnight at the beginning of the
263 given date. Defaults to 0.
264 • minute
266 An integer from 0-59. Defaults to 0.
268 • second
270 An integer from 0-61. Values of 60 or 61 are only allowed when the
272 specified date and time have a leap second. Defaults to 0.
273 • nanosecond
275 An integer that is greater than or equal to 0. If this number is
277 greater than 1 billion, it will be normalized into the second value
278 for the DateTime object. Defaults to 0
279 • locale
281 A string containing a locale code, like "en-US" or "zh-Hant-TW", or
283 an object returned by "DateTime::Locale->load". See the
284 DateTime::Locale documentation for details. Defaults to the value
285 of "DateTime->DefaultLocale", or "en-US" if the class default has
286 not been set.
287 • time_zone
289 A string containing a time zone name like "America/Chicago" or a
291 DateTime::TimeZone object. Defaults to the value of
292 $ENV{PERL_DATETIME_DEFAULT_TZ} or "floating" if that env var is not
293 set. See "Globally Setting a Default Time Zone" for more details on
294 that env var (and why you should not use it).
295 A string will simply be passed to the "DateTime::TimeZone->new"
297 method as its "name" parameter. This string may be an Olson DB time
298 zone name ("America/Chicago"), an offset string ("+0630"), or the
299 words "floating" or "local". See the "DateTime::TimeZone"
300 documentation for more details.
301 • formatter
303 An object or class name with a "format_datetime" method. This will
305 be used to stringify the DateTime object. This is optional. If it
306 is not specified, then stringification calls "$self->iso8601".
307 Invalid parameter types (like an array reference) will cause the
309 constructor to die.
310 Parsing Dates
312 This module does not parse dates! That means there is no constructor to
314 which you can pass things like "March 3, 1970 12:34".
315 Instead, take a look at the various DateTime::Format::*
317 <https://metacpan.org/search?q=datetime%3A%3Aformat> modules on CPAN.
318 These parse all sorts of different date formats, and you're bound to
319 find something that can handle your particular needs.
320 Ambiguous Local Times
322 Because of Daylight Saving Time, it is possible to specify a local time
324 that is ambiguous. For example, in the US in 2003, the transition from
325 to saving to standard time occurred on October 26, at 02:00:00 local
326 time. The local clock changed from 01:59:59 (saving time) to 01:00:00
327 (standard time). This means that the hour from 01:00:00 through
328 01:59:59 actually occurs twice, though the UTC time continues to move
329 forward.
330 If you specify an ambiguous time, then the latest UTC time is always
332 used, in effect always choosing standard time. In this case, you can
333 simply subtract an hour from the object in order to move to saving
334 time, for example:
335 # This object represent 01:30:00 standard time
337 my $dt = DateTime->new(
338 year => 2003,
339 month => 10,
340 day => 26,
341 hour => 1,
342 minute => 30,
343 second => 0,
344 time_zone => 'America/Chicago',
345 );
346 print $dt->hms; # prints 01:30:00
348 # Now the object represent 01:30:00 saving time
350 $dt->subtract( hours => 1 );
351 print $dt->hms; # still prints 01:30:00
353 Alternately, you could create the object with the UTC time zone and
355 then call the "set_time_zone" method to change the time zone. This is a
356 good way to ensure that the time is not ambiguous.
357 Invalid Local Times
359 Another problem introduced by Daylight Saving Time is that certain
361 local times just do not exist. For example, in the US in 2003, the
362 transition from standard to saving time occurred on April 6, at the
363 change to 2:00:00 local time. The local clock changed from 01:59:59
364 (standard time) to 03:00:00 (saving time). This means that there is no
365 02:00:00 through 02:59:59 on April 6!
366 Attempting to create an invalid time currently causes a fatal error.
368 DateTime->from_epoch( epoch => $epoch, ... )
370 This class method can be used to construct a new DateTime object from
372 an epoch time instead of components. Just as with the "new" method, it
373 accepts "time_zone", "locale", and "formatter" parameters.
374 If the epoch value is a non-integral value, it will be rounded to
376 nearest microsecond.
377 By default, the returned object will be in the UTC time zone.
379 DateTime->now( ... )
381 This class method is equivalent to calling "from_epoch" with the value
383 returned from Perl's "time" function. Just as with the "new" method, it
384 accepts "time_zone" and "locale" parameters.
385 By default, the returned object will be in the UTC time zone.
387 If you want sub-second resolution, use the DateTime::HiRes module's
389 "DateTime::HiRes->now" method instead.
390 DateTime->today( ... )
392 This class method is equivalent to:
394 DateTime->now(@_)->truncate( to => 'day' );
396 DateTime->last_day_of_month( ... )
398 This constructor takes the same arguments as can be given to the "new"
400 method, except for "day". Additionally, both "year" and "month" are
401 required.
402 DateTime->from_day_of_year( ... )
404 This constructor takes the same arguments as can be given to the "new"
406 method, except that it does not accept a "month" or "day" argument.
407 Instead, it requires both "year" and "day_of_year". The day of year
408 must be between 1 and 366, and 366 is only allowed for leap years.
409 DateTime->from_object( object => $object, ... )
411 This class method can be used to construct a new DateTime object from
413 any object that implements the "utc_rd_values" method. All
414 "DateTime::Calendar" modules must implement this method in order to
415 provide cross-calendar compatibility. This method accepts a "locale"
416 and "formatter" parameter
417 If the object passed to this method has a "time_zone" method, that is
419 used to set the time zone of the newly created "DateTime" object.
420 Otherwise, the returned object will be in the floating time zone.
422 $dt->clone
424 This object method returns a new object that is replica of the object
426 upon which the method is called.
427 "Get" Methods
429 This class has many methods for retrieving information about an object.
430 $dt->year
432 Returns the year.
434 $dt->ce_year
436 Returns the year according to the BCE/CE numbering system. The year
438 before year 1 in this system is year -1, aka "1 BCE".
439 $dt->era_name
441 Returns the long name of the current era, something like "Before
443 Christ". See the "Locales" section for more details.
444 $dt->era_abbr
446 Returns the abbreviated name of the current era, something like "BC".
448 See the "Locales" section for more details.
449 $dt->christian_era
451 Returns a string, either "BC" or "AD", according to the year.
453 $dt->secular_era
455 Returns a string, either "BCE" or "CE", according to the year.
457 $dt->year_with_era
459 Returns a string containing the year immediately followed by the
461 appropriate era abbreviation, based on the object's locale. The year is
462 the absolute value of "ce_year", so that year 1 is "1" and year 0 is
463 "1BC". See the "Locales" section for more details.
464 $dt->year_with_christian_era
466 Like "year_with_era", but uses the "christian_era" method to get the
468 era name.
469 $dt->year_with_secular_era
471 Like "year_with_era", but uses the "secular_era" method to get the era
473 name.
474 $dt->month
476 Returns the month of the year, from 1..12.
478 Also available as "$dt->mon".
480 $dt->month_name
482 Returns the name of the current month. See the "Locales" section for
484 more details.
485 $dt->month_abbr
487 Returns the abbreviated name of the current month. See the "Locales"
489 section for more details.
490 $dt->day
492 Returns the day of the month, from 1..31.
494 Also available as "$dt->mday" and "$dt->day_of_month".
496 $dt->day_of_week
498 Returns the day of the week as a number, from 1..7, with 1 being Monday
500 and 7 being Sunday.
501 Also available as "$dt->wday" and "$dt->dow".
503 $dt->local_day_of_week
505 Returns the day of the week as a number, from 1..7. The day
507 corresponding to 1 will vary based on the locale. See the "Locales"
508 section for more details.
509 $dt->day_name
511 Returns the name of the current day of the week. See the "Locales"
513 section for more details.
514 $dt->day_abbr
516 Returns the abbreviated name of the current day of the week. See the
518 "Locales" section for more details.
519 $dt->day_of_year
521 Returns the day of the year.
523 Also available as "$dt->doy".
525 $dt->quarter
527 Returns the quarter of the year, from 1..4.
529 $dt->quarter_name
531 Returns the name of the current quarter. See the "Locales" section for
533 more details.
534 $dt->quarter_abbr
536 Returns the abbreviated name of the current quarter. See the "Locales"
538 section for more details.
539 $dt->day_of_quarter
541 Returns the day of the quarter.
543 Also available as "$dt->doq".
545 $dt->weekday_of_month
547 Returns a number from 1..5 indicating which week day of the month this
549 is. For example, June 9, 2003 is the second Monday of the month, and so
550 this method returns 2 for that date.
551 $dt->ymd($optional_separator), $dt->mdy(...), $dt->dmy(...)
553 Each method returns the year, month, and day, in the order indicated by
555 the method name. Years are zero-padded to four digits. Months and days
556 are 0-padded to two digits.
557 By default, the values are separated by a dash (-), but this can be
559 overridden by passing a value to the method.
560 The "$dt->ymd" method is also available as "$dt->date".
562 $dt->hour
564 Returns the hour of the day, from 0..23.
566 $dt->hour_1
568 Returns the hour of the day, from 1..24.
570 $dt->hour_12
572 Returns the hour of the day, from 1..12.
574 $dt->hour_12_0
576 Returns the hour of the day, from 0..11.
578 $dt->am_or_pm
580 Returns the appropriate localized abbreviation, depending on the
582 current hour.
583 $dt->minute
585 Returns the minute of the hour, from 0..59.
587 Also available as "$dt->min".
589 $dt->second
591 Returns the second, from 0..61. The values 60 and 61 are used for leap
593 seconds.
594 Also available as "$dt->sec".
596 $dt->fractional_second
598 Returns the second, as a real number from 0.0 until 61.999999999
600 The values 60 and 61 are used for leap seconds.
602 $dt->millisecond
604 Returns the fractional part of the second as milliseconds (1E-3
606 seconds).
607 Half a second is 500 milliseconds.
609 This value will always be rounded down to the nearest integer.
611 $dt->microsecond
613 Returns the fractional part of the second as microseconds (1E-6
615 seconds).
616 Half a second is 500,000 microseconds.
618 This value will always be rounded down to the nearest integer.
620 $dt->nanosecond
622 Returns the fractional part of the second as nanoseconds (1E-9
624 seconds).
625 Half a second is 500,000,000 nanoseconds.
627 $dt->hms($optional_separator)
629 Returns the hour, minute, and second, all zero-padded to two digits.
631 If no separator is specified, a colon (:) is used by default.
632 Also available as "$dt->time".
634 $dt->datetime($optional_separator)
636 This method is equivalent to:
638 $dt->ymd('-') . 'T' . $dt->hms(':')
640 The $optional_separator parameter allows you to override the separator
642 between the date and time, for e.g. "$dt->datetime(q{ })".
643 This method is also available as "$dt->iso8601", but it's not really a
645 very good ISO8601 format, as it lacks a time zone. If called as
646 "$dt->iso8601" you cannot change the separator, as ISO8601 specifies
647 that "T" must be used to separate them.
648 $dt->rfc3339
650 This formats a datetime in RFC3339 format. This is the same as
652 "$dt->datetime" with an added offset at the end of the string except if
653 the time zone is the floating time zone.
654 If the offset is '+00:00' then this is represented as 'Z'. Otherwise
656 the offset is formatted with a leading sign (+/-) and a colon separated
657 numeric offset with hours and minutes. If the offset has a non-zero
658 seconds component, that is also included.
659 $dt->stringify
661 This method returns a stringified version of the object. It is also how
663 stringification overloading is implemented. If the object has a
664 formatter, then its "format_datetime" method is used to produce a
665 string. Otherwise, this method calls "$dt->iso8601" to produce a
666 string. See "Formatters And Stringification" for details.
667 $dt->is_leap_year
669 This method returns a boolean value indicating whether or not the
671 datetime object is in a leap year.
672 $dt->is_last_day_of_month
674 This method returns a boolean value indicating whether or not the
676 datetime object is the last day of the month.
677 $dt->is_last_day_of_quarter
679 This method returns a boolean value indicating whether or not the
681 datetime object is the last day of the quarter.
682 $dt->is_last_day_of_year
684 This method returns a boolean value indicating whether or not the
686 datetime object is the last day of the year.
687 $dt->month_length
689 This method returns the number of days in the current month.
691 $dt->quarter_length
693 This method returns the number of days in the current quarter.
695 $dt->year_length
697 This method returns the number of days in the current year.
699 $dt->week
701 my ( $week_year, $week_number ) = $dt->week;
703 Returns information about the calendar week for the date. The values
705 returned by this method are also available separately through the
706 "$dt->week_year" and "$dt->week_number" methods.
707 The first week of the year is defined by ISO as the one which contains
709 the fourth day of January, which is equivalent to saying that it's the
710 first week to overlap the new year by at least four days.
711 Typically the week year will be the same as the year that the object is
713 in, but dates at the very beginning of a calendar year often end up in
714 the last week of the prior year, and similarly, the final few days of
715 the year may be placed in the first week of the next year.
716 $dt->week_year
718 Returns the year of the week. See "$dt->week" for details.
720 $dt->week_number
722 Returns the week of the year, from 1..53. See "$dt->week" for details.
724 $dt->week_of_month
726 The week of the month, from 0..5. The first week of the month is the
728 first week that contains a Thursday. This is based on the ICU
729 definition of week of month, and correlates to the ISO8601 week of year
730 definition. A day in the week before the week with the first Thursday
731 will be week 0.
732 $dt->jd, $dt->mjd
734 These return the Julian Day and Modified Julian Day, respectively. The
736 value returned is a floating point number. The fractional portion of
737 the number represents the time portion of the datetime.
738 The Julian Day is a count of days since the beginning of the Julian
740 Period, which starts with day 0 at noon on January 1, -4712.
741 The Modified Julian Day is a count of days since midnight on November
743 17, 1858.
744 These methods always refer to the local time, so the Julian Day is the
746 same for a given datetime regardless of its time zone. Or in other
747 words, 2020-12-04T13:01:57 in "America/Chicago" has the same Julian Day
748 as 2020-12-04T13:01:57 in "Asia/Taipei".
749 $dt->time_zone
751 This returns the DateTime::TimeZone object for the datetime object.
753 $dt->offset
755 This returns the offset from UTC, in seconds, of the datetime object's
757 time zone.
758 $dt->is_dst
760 Returns a boolean indicating whether or not the datetime's time zone is
762 currently in Daylight Saving Time or not.
763 $dt->time_zone_long_name
765 This is a shortcut for "$dt->time_zone->name". It's provided so that
767 one can use "%{time_zone_long_name}" as a strftime format specifier.
768 $dt->time_zone_short_name
770 This method returns the time zone abbreviation for the current time
772 zone, such as "PST" or "GMT". These names are not definitive, and
773 should not be used in any application intended for general use by users
774 around the world. That's because it's possible for multiple time zones
775 to have the same abbreviation.
776 $dt->strftime( $format, ... )
778 This method implements functionality similar to the "strftime" method
780 in C. However, if given multiple format strings, then it will return
781 multiple scalars, one for each format string.
782 See the "strftime Patterns" section for a list of all possible strftime
784 patterns.
785 If you give a pattern that doesn't exist, then it is simply treated as
787 text.
788 Note that any deviation from the POSIX standard is probably a bug.
790 DateTime should match the output of "POSIX::strftime" for any given
791 pattern.
792 $dt->format_cldr( $format, ... )
794 This method implements formatting based on the CLDR date patterns. If
796 given multiple format strings, then it will return multiple scalars,
797 one for each format string.
798 See the "CLDR Patterns" section for a list of all possible CLDR
800 patterns.
801 If you give a pattern that doesn't exist, then it is simply treated as
803 text.
804 $dt->epoch
806 Returns the UTC epoch value for the datetime object. Datetimes before
808 the start of the epoch will be returned as a negative number.
809 The return value from this method is always an integer number of
811 seconds.
812 Since the epoch does not account for leap seconds, the epoch time for
814 1972-12-31T23:59:60 (UTC) is exactly the same as that for
815 1973-01-01T00:00:00.
816 $dt->hires_epoch
818 Returns the epoch as a floating point number. The floating point
820 portion of the value represents the nanosecond value of the object.
821 This method is provided for compatibility with the "Time::HiRes"
822 module.
823 Note that this method suffers from the imprecision of floating point
825 numbers, and the result may end up rounded to an arbitrary degree
826 depending on your platform.
827 my $dt = DateTime->new( year => 2012, nanosecond => 4 );
829 say $dt->hires_epoch;
830 On my system, this simply prints 1325376000 because adding 0.000000004
832 to 1325376000 returns 1325376000.
833 $dt->is_finite, $dt->is_infinite
835 These methods allow you to distinguish normal datetime objects from
837 infinite ones. Infinite datetime objects are documented in
838 DateTime::Infinite.
839 $dt->utc_rd_values
841 Returns the current UTC Rata Die days, seconds, and nanoseconds as a
843 three element list. This exists primarily to allow other calendar
844 modules to create objects based on the values provided by this object.
845 $dt->local_rd_values
847 Returns the current local Rata Die days, seconds, and nanoseconds as a
849 three element list. This exists for the benefit of other modules which
850 might want to use this information for date math, such as
851 DateTime::Event::Recurrence.
852 $dt->leap_seconds
854 Returns the number of leap seconds that have happened up to the
856 datetime represented by the object. For floating datetimes, this always
857 returns 0.
858 $dt->utc_rd_as_seconds
860 Returns the current UTC Rata Die days and seconds purely as seconds.
862 This number ignores any fractional seconds stored in the object, as
863 well as leap seconds.
864 $dt->locale
866 Returns the datetime's DateTime::Locale object.
868 $dt->formatter
870 Returns the current formatter object or class. See "Formatters And
872 Stringification" for details.
873 "Set" Methods
875 The remaining methods provided by "DateTime", except where otherwise
876 specified, return the object itself, thus making method chaining
877 possible. For example:
878 my $dt = DateTime->now->set_time_zone( 'Australia/Sydney' );
880 my $first = DateTime
882 ->last_day_of_month( year => 2003, month => 3 )
883 ->add( days => 1 )
884 ->subtract( seconds => 1 );
885 $dt->set( .. )
887 This method can be used to change the local components of a date time.
889 This method accepts any parameter allowed by the "new" method except
890 for "locale" or "time_zone". Use "set_locale" and "set_time_zone" for
891 those instead.
892 This method performs parameter validation just like the "new" method.
894 Do not use this method to do date math. Use the "add" and "subtract"
896 methods instead.
897 $dt->set_year, $dt->set_month, etc.
899 DateTime has a "set_*" method for every item that can be passed to the
901 constructor:
902 • $dt->set_year
904 • $dt->set_month
906 • $dt->set_day
908 • $dt->set_hour
910 • $dt->set_minute
912 • $dt->set_second
914 • $dt->set_nanosecond
916 These are shortcuts to calling "set" with a single key. They all take a
918 single parameter.
919 $dt->truncate( to => ... )
921 This method allows you to reset some of the local time components in
923 the object to their "zero" values. The "to" parameter is used to
924 specify which values to truncate, and it may be one of "year",
925 "quarter", "month", "week", "local_week", "day", "hour", "minute", or
926 "second".
927 For example, if "month" is specified, then the local day becomes 1, and
929 the hour, minute, and second all become 0.
930 If "week" is given, then the datetime is set to the Monday of the week
932 in which it occurs, and the time components are all set to 0. If you
933 truncate to "local_week", then the first day of the week is locale-
934 dependent. For example, in the "en-US" locale, the first day of the
935 week is Sunday.
936 $dt->set_locale($locale)
938 Sets the object's locale. You can provide either a locale code like
940 "en-US" or an object returned by "DateTime::Locale->load".
941 $dt->set_time_zone($tz)
943 This method accepts either a time zone object or a string that can be
945 passed as the "name" parameter to "DateTime::TimeZone->new". If the new
946 time zone's offset is different from the old time zone, then the local
947 time is adjusted accordingly.
948 For example:
950 my $dt = DateTime->new(
952 year => 2000,
953 month => 5,
954 day => 10,
955 hour => 15,
956 minute => 15,
957 time_zone => 'America/Los_Angeles',
958 );
959 print $dt->hour; # prints 15
961 $dt->set_time_zone('America/Chicago');
963 print $dt->hour; # prints 17
965 If the old time zone was a floating time zone, then no adjustments to
967 the local time are made, except to account for leap seconds. If the new
968 time zone is floating, then the UTC time is adjusted in order to leave
969 the local time untouched.
970 Fans of Tsai Ming-Liang's films will be happy to know that this does
972 work:
973 my $dt = DateTime->now( time_zone => 'Asia/Taipei' );
975 $dt->set_time_zone('Europe/Paris');
976 Yes, now we can know "ni3 na4 bian1 ji2 dian3?"
978 $dt->set_formatter($formatter)
980 Sets the formatter for the object. See "Formatters And Stringification"
982 for details.
983 You can set this to "undef" to revert to the default formatter.
985 Math Methods
987 Like the set methods, math related methods always return the object
988 itself, to allow for chaining:
989 $dt->add( days => 1 )->subtract( seconds => 1 );
991 $dt->duration_class
993 This returns "DateTime::Duration", but exists so that a subclass of
995 "DateTime" can provide a different value.
996 $dt->add_duration($duration_object)
998 This method adds a DateTime::Duration to the current datetime. See the
1000 DateTime::Duration docs for more details.
1001 $dt->add( parameters for DateTime::Duration )
1003 This method is syntactic sugar around the "$dt->add_duration" method.
1005 It simply creates a new DateTime::Duration object using the parameters
1006 given, and then calls the "$dt->add_duration" method.
1007 $dt->add($duration_object)
1009 A synonym of "$dt->add_duration($duration_object)".
1011 $dt->subtract_duration($duration_object)
1013 When given a DateTime::Duration object, this method simply calls
1015 "$dur->inverse" on that object and passes that new duration to the
1016 "$self->add_duration" method.
1017 $dt->subtract( DateTime::Duration->new parameters )
1019 Like "$dt->add", this is syntactic sugar for the
1021 "$dt->subtract_duration" method.
1022 $dt->subtract($duration_object)
1024 A synonym of "$dt->subtract_duration($duration_object)".
1026 $dt->subtract_datetime($datetime)
1028 This method returns a new DateTime::Duration object representing the
1030 difference between the two dates. The duration is relative to the
1031 object from which $datetime is subtracted. For example:
1032 2003-03-15 00:00:00.00000000
1034 - 2003-02-15 00:00:00.00000000
1035 -------------------------------
1036 = 1 month
1037 Note that this duration is not an absolute measure of the amount of
1039 time between the two datetimes, because the length of a month varies,
1040 as well as due to the presence of leap seconds.
1041 The returned duration may have deltas for months, days, minutes,
1043 seconds, and nanoseconds.
1044 $dt->delta_md($datetime)
1046 $dt->delta_days($datetime)
1048 Each of these methods returns a new DateTime::Duration object
1050 representing some portion of the difference between two datetimes. The
1051 "$dt->delta_md" method returns a duration which contains only the month
1052 and day portions of the duration is represented. The "$dt->delta_days"
1053 method returns a duration which contains only days.
1054 The "$dt->delta_md" and "$dt->delta_days" methods truncate the duration
1056 so that any fractional portion of a day is ignored. Both of these
1057 methods operate on the date portion of a datetime only, and so
1058 effectively ignore the time zone.
1059 Unlike the subtraction methods, these methods always return a positive
1061 (or zero) duration.
1062 $dt->delta_ms($datetime)
1064 Returns a duration which contains only minutes and seconds. Any day and
1066 month differences are converted to minutes and seconds. This method
1067 always returns a positive (or zero) duration.
1068 $dt->subtract_datetime_absolute($datetime)
1070 This method returns a new DateTime::Duration object representing the
1072 difference between the two dates in seconds and nanoseconds. This is
1073 the only way to accurately measure the absolute amount of time between
1074 two datetimes, since units larger than a second do not represent a
1075 fixed number of seconds.
1076 Note that because of leap seconds, this may not return the same result
1078 as doing this math based on the value returned by "$dt->epoch".
1079 $dt->is_between( $lower, $upper )
1081 Checks whether $dt is strictly between two other DateTime objects.
1083 "Strictly" means that $dt must be greater than $lower and less than
1085 $upper. If it is equal to either object then this method returns false.
1086 Class Methods
1088 DateTime->DefaultLocale($locale)
1089 This can be used to specify the default locale to be used when creating
1091 DateTime objects. If unset, then "en-US" is used.
1092 This exists for backwards compatibility, but is probably best avoided.
1094 This will change the default locale for every "DateTime" object created
1095 in your application, even those created by third party libraries which
1096 also use "DateTime".
1097 DateTime->compare( $dt1, $dt2 ), DateTime->compare_ignore_floating(
1099 $dt1, $dt2 )
1100 $cmp = DateTime->compare( $dt1, $dt2 );
1102 $cmp = DateTime->compare_ignore_floating( $dt1, $dt2 );
1104 This method compare two DateTime objects. The semantics are compatible
1106 with Perl's "sort" function; it returns "-1" if "$dt1 < $dt2", 0 if
1107 "$dt1 == $dt2", 1 if "$dt1 > $dt2".
1108 If one of the two DateTime objects has a floating time zone, it will
1110 first be converted to the time zone of the other object. This is what
1111 you want most of the time, but it can lead to inconsistent results when
1112 you compare a number of DateTime objects, some of which are floating,
1113 and some of which are in other time zones.
1114 If you want to have consistent results (because you want to sort an
1116 array of objects, for example), you can use the
1117 "compare_ignore_floating" method:
1118 @dates = sort { DateTime->compare_ignore_floating( $a, $b ) } @dates;
1120 In this case, objects with a floating time zone will be sorted as if
1122 they were UTC times.
1123 Since DateTime objects overload comparison operators, this:
1125 @dates = sort @dates;
1127 is equivalent to this:
1129 @dates = sort { DateTime->compare( $a, $b ) } @dates;
1131 DateTime objects can be compared to any other calendar class that
1133 implements the "utc_rd_values" method.
1134 Testing Code That Uses DateTime
1136 If you are trying to test code that calls uses DateTime, you may want
1137 to be to explicitly set the value returned by Perl's "time" builtin.
1138 This builtin is called by "DateTime->now" and "DateTime->today".
1139 You can override "CORE::GLOBAL::time", but this will only work if you
1141 do this before loading DateTime. If doing this is inconvenient, you can
1142 also override "DateTime::_core_time":
1143 no warnings 'redefine';
1145 local *DateTime::_core_time = sub { return 42 };
1146 DateTime is guaranteed to call this subroutine to get the current
1148 "time" value. You can also override the "_core_time" sub in a subclass
1149 of DateTime and use that.
1150 How DateTime Math Works
1152 It's important to have some understanding of how datetime math is
1153 implemented in order to effectively use this module and
1154 DateTime::Duration.
1155 Making Things Simple
1157 If you want to simplify your life and not have to think too hard about
1159 the nitty-gritty of datetime math, I have several recommendations:
1160 • use the floating time zone
1162 If you do not care about time zones or leap seconds, use the
1164 "floating" timezone:
1165 my $dt = DateTime->now( time_zone => 'floating' );
1167 Math done on two objects in the floating time zone produces very
1169 predictable results.
1170 Note that in most cases you will want to start by creating an
1172 object in a specific zone and then convert it to the floating time
1173 zone. When an object goes from a real zone to the floating zone,
1174 the time for the object remains the same.
1175 This means that passing the floating zone to a constructor may not
1177 do what you want.
1178 my $dt = DateTime->now( time_zone => 'floating' );
1180 is equivalent to
1182 my $dt = DateTime->now( time_zone => 'UTC' )->set_time_zone('floating');
1184 This might not be what you wanted. Instead, you may prefer to do
1186 this:
1187 my $dt = DateTime->now( time_zone => 'local' )->set_time_zone('floating');
1189 • use UTC for all calculations
1191 If you do care about time zones (particularly DST) or leap seconds,
1193 try to use non-UTC time zones for presentation and user input only.
1194 Convert to UTC immediately and convert back to the local time zone
1195 for presentation:
1196 my $dt = DateTime->new( %user_input, time_zone => $user_tz );
1198 $dt->set_time_zone('UTC');
1199 # do various operations - store it, retrieve it, add, subtract, etc.
1201 $dt->set_time_zone($user_tz);
1203 print $dt->datetime;
1204 • math on non-UTC time zones
1206 If you need to do date math on objects with non-UTC time zones,
1208 please read the caveats below carefully. The results "DateTime"
1209 produces are predictable, correct, and mostly intuitive, but
1210 datetime math gets very ugly when time zones are involved, and
1211 there are a few strange corner cases involving subtraction of two
1212 datetimes across a DST change.
1213 If you can always use the floating or UTC time zones, you can skip
1215 ahead to "Leap Seconds and Date Math"
1216 • date vs datetime math
1218 If you only care about the date (calendar) portion of a datetime,
1220 you should use either "$dt->delta_md"> or "$dt->delta_days", not
1221 "$dt->subtract_datetime". This will give predictable, unsurprising
1222 results, free from DST-related complications.
1223 • $dt->subtract_datetime and $dt->add_duration
1225 You must convert your datetime objects to the UTC time zone before
1227 doing date math if you want to make sure that the following
1228 formulas are always true:
1229 $dt2 - $dt1 = $dur
1231 $dt1 + $dur = $dt2
1232 $dt2 - $dur = $dt1
1233 Note that using "$dt->delta_days" ensures that this formula always
1235 works, regardless of the time zones of the objects involved, as
1236 does using "$dt->subtract_datetime_absolute". Other methods of
1237 subtraction are not always reversible.
1238 • never do math on two objects where only one is in the floating time
1240 zone
1241 The date math code accounts for leap seconds whenever the
1243 "DateTime" object is not in the floating time zone. If you try to
1244 do math where one object is in the floating zone and the other
1245 isn't, the results will be confusing and wrong.
1246 Adding a Duration to a DateTime
1248 The parts of a duration can be broken down into five parts. These are
1250 months, days, minutes, seconds, and nanoseconds. Adding one month to a
1251 date is different than adding 4 weeks or 28, 29, 30, or 31 days.
1252 Similarly, due to DST and leap seconds, adding a day can be different
1253 than adding 86,400 seconds, and adding a minute is not exactly the same
1254 as 60 seconds.
1255 We cannot convert between these units, except for seconds and
1257 nanoseconds, because there is no fixed conversion between most pairs of
1258 units. That is because of things like leap seconds, DST changes, etc.
1259 "DateTime" always adds (or subtracts) days, then months, minutes, and
1261 then seconds and nanoseconds. If there are any boundary overflows,
1262 these are normalized at each step. For the days and months the local
1263 (not UTC) values are used. For minutes and seconds, the local values
1264 are used. This generally just works.
1265 This means that adding one month and one day to February 28, 2003 will
1267 produce the date April 1, 2003, not March 29, 2003.
1268 my $dt = DateTime->new( year => 2003, month => 2, day => 28 );
1270 $dt->add( months => 1, days => 1 );
1272 # 2003-04-01 - the result
1274 On the other hand, if we add months first, and then separately add
1276 days, we end up with March 29, 2003:
1277 $dt->add( months => 1 )->add( days => 1 );
1279 # 2003-03-29
1281 We see similar strangeness when math crosses a DST boundary:
1283 my $dt = DateTime->new(
1285 year => 2003,
1286 month => 4,
1287 day => 5,
1288 hour => 1,
1289 minute => 58,
1290 time_zone => "America/Chicago",
1291 );
1292 $dt->add( days => 1, minutes => 3 );
1294 # 2003-04-06 02:01:00
1295 $dt->add( minutes => 3 )->add( days => 1 );
1297 # 2003-04-06 03:01:00
1298 Note that if you converted the datetime object to UTC first you would
1300 get predictable results.
1301 If you want to know how many seconds a DateTime::Duration object
1303 represents, you have to add it to a datetime to find out, so you could
1304 do:
1305 my $now = DateTime->now( time_zone => 'UTC' );
1307 my $later = $now->clone->add_duration($duration);
1308 my $seconds_dur = $later->subtract_datetime_absolute($now);
1310 This returns a DateTime::Duration which only contains seconds and
1312 nanoseconds.
1313 If we were add the duration to a different "DateTime" object we might
1315 get a different number of seconds.
1316 DateTime::Duration supports three different end-of-month algorithms for
1318 adding months. This comes into play when an addition results in a day
1319 past the end of the following month (for example, adding one month to
1320 January 30).
1321 # 2010-08-31 + 1 month = 2010-10-01
1323 $dt->add( months => 1, end_of_month => 'wrap' );
1324 # 2010-01-30 + 1 month = 2010-02-28
1326 $dt->add( months => 1, end_of_month => 'limit' );
1327 # 2010-04-30 + 1 month = 2010-05-31
1329 $dt->add( months => 1, end_of_month => 'preserve' );
1330 By default, it uses "wrap" for positive durations and "preserve" for
1332 negative durations. See DateTime::Duration for a detailed explanation
1333 of these algorithms.
1334 If you need to do lots of work with durations, take a look at the
1336 DateTime::Format::Duration module, which lets you present information
1337 from durations in many useful ways.
1338 There are other subtract/delta methods in "DateTime" to generate
1340 different types of durations. These methods are
1341 "$dt->subtract_datetime", "$dt->subtract_datetime_absolute",
1342 "$dt->delta_md", "$dt->delta_days", and "$dt->delta_ms".
1343 DateTime Subtraction
1345 Date subtraction is done based solely on the two object's local
1347 datetimes, with one exception to handle DST changes. Also, if the two
1348 datetime objects are in different time zones, one of them is converted
1349 to the other's time zone first before subtraction. This is best
1350 explained through examples:
1351 The first of these probably makes the most sense:
1353 # not DST
1355 my $dt1 = DateTime->new(
1356 year => 2003,
1357 month => 5,
1358 day => 6,
1359 time_zone => 'America/Chicago',
1360 );
1361 # is DST
1363 my $dt2 = DateTime->new(
1364 year => 2003,
1365 month => 11,
1366 day => 6,
1367 time_zone => 'America/Chicago',
1368 );
1369 # 6 months
1371 my $dur = $dt2->subtract_datetime($dt1);
1372 Nice and simple.
1374 This one is a little trickier, but still fairly logical:
1376 # is DST
1378 my $dt1 = DateTime->new(
1379 year => 2003,
1380 month => 4,
1381 day => 5,
1382 hour => 1,
1383 minute => 58,
1384 time_zone => "America/Chicago",
1385 );
1386 # not DST
1388 my $dt2 = DateTime->new(
1389 year => 2003,
1390 month => 4,
1391 day => 7,
1392 hour => 2,
1393 minute => 1,
1394 time_zone => "America/Chicago",
1395 );
1396 # 2 days and 3 minutes
1398 my $dur = $dt2->subtract_datetime($dt1);
1399 Which contradicts the result this one gives, even though they both make
1401 sense:
1402 # is DST
1404 my $dt1 = DateTime->new(
1405 year => 2003,
1406 month => 4,
1407 day => 5,
1408 hour => 1,
1409 minute => 58,
1410 time_zone => "America/Chicago",
1411 );
1412 # not DST
1414 my $dt2 = DateTime->new(
1415 year => 2003,
1416 month => 4,
1417 day => 6,
1418 hour => 3,
1419 minute => 1,
1420 time_zone => "America/Chicago",
1421 );
1422 # 1 day and 3 minutes
1424 my $dur = $dt2->subtract_datetime($dt1);
1425 This last example illustrates the "DST" exception mentioned earlier.
1427 The exception accounts for the fact 2003-04-06 only lasts 23 hours.
1428 And finally:
1430 my $dt2 = DateTime->new(
1432 year => 2003,
1433 month => 10,
1434 day => 26,
1435 hour => 1,
1436 time_zone => 'America/Chicago',
1437 );
1438 my $dt1 = $dt2->clone->subtract( hours => 1 );
1440 # 60 minutes
1442 my $dur = $dt2->subtract_datetime($dt1);
1443 This seems obvious until you realize that subtracting 60 minutes from
1445 $dt2 in the above example still leaves the clock time at "01:00:00".
1446 This time we are accounting for a 25 hour day.
1447 Reversibility
1449 Date math operations are not always reversible. This is because of the
1451 way that addition operations are ordered. As was discussed earlier,
1452 adding 1 day and 3 minutes in one call to "$dt->add"> is not the same
1453 as first adding 3 minutes and 1 day in two separate calls.
1454 If we take a duration returned from "$dt->subtract_datetime" and then
1456 try to add or subtract that duration from one of the datetimes we just
1457 used, we sometimes get interesting results:
1458 my $dt1 = DateTime->new(
1460 year => 2003,
1461 month => 4,
1462 day => 5,
1463 hour => 1,
1464 minute => 58,
1465 time_zone => "America/Chicago",
1466 );
1467 my $dt2 = DateTime->new(
1469 year => 2003,
1470 month => 4,
1471 day => 6,
1472 hour => 3,
1473 minute => 1,
1474 time_zone => "America/Chicago",
1475 );
1476 # 1 day and 3 minutes
1478 my $dur = $dt2->subtract_datetime($dt1);
1479 # gives us $dt2
1481 $dt1->add_duration($dur);
1482 # gives us 2003-04-05 02:58:00 - 1 hour later than $dt1
1484 $dt2->subtract_duration($dur);
1485 The "$dt->subtract_duration" operation gives us a (perhaps) unexpected
1487 answer because it first subtracts one day to get 2003-04-05T03:01:00
1488 and then subtracts 3 minutes to get the final result.
1489 If we explicitly reverse the order we can get the original value of
1491 $dt1. This can be facilitated by the DateTime::Duration class's
1492 "$dur->calendar_duration" and "$dur->clock_duration" methods:
1493 $dt2->subtract_duration( $dur->clock_duration )
1495 ->subtract_duration( $dur->calendar_duration );
1496 Leap Seconds and Date Math
1498 The presence of leap seconds can cause even more anomalies in date
1500 math. For example, the following is a legal datetime:
1501 my $dt = DateTime->new(
1503 year => 1972,
1504 month => 12,
1505 day => 31,
1506 hour => 23,
1507 minute => 59,
1508 second => 60,
1509 time_zone => 'UTC'
1510 );
1511 If we add one month ...
1513 $dt->add( months => 1 );
1515 ... the datetime is now "1973-02-01 00:00:00", because there is no
1517 23:59:60 on 1973-01-31.
1518 Leap seconds also force us to distinguish between minutes and seconds
1520 during date math. Given the following datetime ...
1521 my $dt = DateTime->new(
1523 year => 1972,
1524 month => 12,
1525 day => 31,
1526 hour => 23,
1527 minute => 59,
1528 second => 30,
1529 time_zone => 'UTC'
1530 );
1531 ... we will get different results when adding 1 minute than we get if
1533 we add 60 seconds. This is because in this case, the last minute of the
1534 day, beginning at 23:59:00, actually contains 61 seconds.
1535 Here are the results we get:
1537 # 1972-12-31 23:59:30 - our starting datetime
1539 my $dt = DateTime->new(
1540 year => 1972,
1541 month => 12,
1542 day => 31,
1543 hour => 23,
1544 minute => 59,
1545 second => 30,
1546 time_zone => 'UTC'
1547 );
1548 # 1973-01-01 00:00:30 - one minute later
1550 $dt->clone->add( minutes => 1 );
1551 # 1973-01-01 00:00:29 - 60 seconds later
1553 $dt->clone->add( seconds => 60 );
1554 # 1973-01-01 00:00:30 - 61 seconds later
1556 $dt->clone->add( seconds => 61 );
1557 Local vs. UTC and 24 hours vs. 1 day
1559 When math crosses a daylight saving boundary, a single day may have
1561 more or less than 24 hours.
1562 For example, if you do this ...
1564 my $dt = DateTime->new(
1566 year => 2003,
1567 month => 4,
1568 day => 5,
1569 hour => 2,
1570 time_zone => 'America/Chicago',
1571 );
1572 $dt->add( days => 1 );
1574 ... then you will produce an invalid local time, and therefore an
1576 exception will be thrown.
1577 However, this works ...
1579 my $dt = DateTime->new(
1581 year => 2003,
1582 month => 4,
1583 day => 5,
1584 hour => 2,
1585 time_zone => 'America/Chicago',
1586 );
1587 $dt->add( hours => 24 );
1589 ... and produces a datetime with the local time of "03:00".
1591 If all this makes your head hurt, there is a simple alternative. Just
1593 convert your datetime object to the "UTC" time zone before doing date
1594 math on it, and switch it back to the local time zone afterwards. This
1595 avoids the possibility of having date math throw an exception, and
1596 makes sure that 1 day equals 24 hours. Of course, this may not always
1597 be desirable, so caveat user!
1598 Overloading
1600 This module explicitly overloads the addition (+), subtraction (-),
1601 string and numeric comparison operators. This means that the following
1602 all do sensible things:
1603 my $new_dt = $dt + $duration_obj;
1605 my $new_dt = $dt - $duration_obj;
1607 my $duration_obj = $dt - $new_dt;
1609 foreach my $dt ( sort @dts ) {...}
1611 Additionally, the fallback parameter is set to true, so other derivable
1613 operators (+=, -=, etc.) will work properly. Do not expect increment
1614 (++) or decrement (--) to do anything useful.
1615 The string comparison operators, "eq" or "ne", will use the string
1617 value to compare with non-DateTime objects.
1618 DateTime objects do not have a numeric value, using "==" or "<=>" to
1620 compare a DateTime object with a non-DateTime object will result in an
1621 exception. To safely sort mixed DateTime and non-DateTime objects, use
1622 "sort { $a cmp $b } @dates".
1623 The module also overloads stringification using the object's formatter,
1625 defaulting to "iso8601" method. See "Formatters And Stringification"
1626 for details.
1627 Formatters And Stringification
1629 You can optionally specify a "formatter", which is usually a
1630 "DateTime::Format::*" object or class, to control the stringification
1631 of the DateTime object.
1632 Any of the constructor methods can accept a formatter argument:
1634 my $formatter = DateTime::Format::Strptime->new(...);
1636 my $dt = DateTime->new( year => 2004, formatter => $formatter );
1637 Or, you can set it afterwards:
1639 $dt->set_formatter($formatter);
1641 $formatter = $dt->formatter;
1642 Once you set the formatter, the overloaded stringification method will
1644 use the formatter. If unspecified, the "iso8601" method is used.
1645 A formatter can be handy when you know that in your application you
1647 want to stringify your DateTime objects into a special format all the
1648 time, for example in Postgres format.
1649 If you provide a formatter class name or object, it must implement a
1651 "format_datetime" method. This method will be called with just the
1652 "DateTime" object as its argument.
1653 CLDR Patterns
1655 The CLDR pattern language is both more powerful and more complex than
1656 strftime. Unlike strftime patterns, you often have to explicitly escape
1657 text that you do not want formatted, as the patterns are simply letters
1658 without any prefix.
1659 For example, "yyyy-MM-dd" is a valid CLDR pattern. If you want to
1661 include any lower or upper case ASCII characters as-is, you can
1662 surround them with single quotes ('). If you want to include a single
1663 quote, you must escape it as two single quotes ('').
1664 my $pattern1 = q{'Today is ' EEEE};
1666 my $pattern2 = q{'It is now' h 'o''clock' a};
1667 Spaces and any non-letter text will always be passed through as-is.
1669 Many CLDR patterns which produce numbers will pad the number with
1671 leading zeroes depending on the length of the format specifier. For
1672 example, "h" represents the current hour from 1-12. If you specify "hh"
1673 then hours 1-9 will have a leading zero prepended.
1674 However, CLDR often uses five of a letter to represent the narrow form
1676 of a pattern. This inconsistency is necessary for backwards
1677 compatibility.
1678 There are many cases where CLDR patterns distinguish between the
1680 "format" and "stand-alone" forms of a pattern. The format pattern is
1681 used when the thing in question is being placed into a larger string.
1682 The stand-alone form is used when displaying that item by itself, for
1683 example in a calendar.
1684 There are also many cases where CLDR provides three sizes for each
1686 item, wide (the full name), abbreviated, and narrow. The narrow form is
1687 often just a single character, for example "T" for "Tuesday", and may
1688 not be unique.
1689 CLDR provides a fairly complex system for localizing time zones that we
1691 ignore entirely. The time zone patterns just use the information
1692 provided by "DateTime::TimeZone", and do not follow the CLDR spec.
1693 The output of a CLDR pattern is always localized, when applicable.
1695 CLDR provides the following patterns:
1697 • G{1,3}
1699 The abbreviated era (BC, AD).
1701 • GGGG
1703 The wide era (Before Christ, Anno Domini).
1705 • GGGGG
1707 The narrow era, if it exists (but it mostly doesn't).
1709 • y and y{3,}
1711 The year, zero-prefixed as needed. Negative years will start with a
1713 "-", and this will be included in the length calculation.
1714 In other, words the "yyyyy" pattern will format year -1234 as
1716 "-1234", not "-01234".
1717 • yy
1719 This is a special case. It always produces a two-digit year, so
1721 "1976" becomes "76". Negative years will start with a "-", making
1722 them one character longer.
1723 • Y{1,}
1725 The year in "week of the year" calendars, from "$dt->week_year".
1727 • u{1,}
1729 Same as "y" except that "uu" is not a special case.
1731 • Q{1,2}
1733 The quarter as a number (1..4).
1735 • QQQ
1737 The abbreviated format form for the quarter.
1739 • QQQQ
1741 The wide format form for the quarter.
1743 • q{1,2}
1745 The quarter as a number (1..4).
1747 • qqq
1749 The abbreviated stand-alone form for the quarter.
1751 • qqqq
1753 The wide stand-alone form for the quarter.
1755 • M{1,2]
1757 The numerical month.
1759 • MMM
1761 The abbreviated format form for the month.
1763 • MMMM
1765 The wide format form for the month.
1767 • MMMMM
1769 The narrow format form for the month.
1771 • L{1,2]
1773 The numerical month.
1775 • LLL
1777 The abbreviated stand-alone form for the month.
1779 • LLLL
1781 The wide stand-alone form for the month.
1783 • LLLLL
1785 The narrow stand-alone form for the month.
1787 • w{1,2}
1789 The week of the year, from "$dt->week_number".
1791 • W
1793 The week of the month, from "$dt->week_of_month".
1795 • d{1,2}
1797 The numeric day of the month.
1799 • D{1,3}
1801 The numeric day of the year.
1803 • F
1805 The day of the week in the month, from "$dt->weekday_of_month".
1807 • g{1,}
1809 The modified Julian day, from "$dt->mjd".
1811 • E{1,3} and eee
1813 The abbreviated format form for the day of the week.
1815 • EEEE and eeee
1817 The wide format form for the day of the week.
1819 • EEEEE and eeeee
1821 The narrow format form for the day of the week.
1823 • e{1,2}
1825 The local numeric day of the week, from 1 to 7. This number depends
1827 on what day is considered the first day of the week, which varies
1828 by locale. For example, in the US, Sunday is the first day of the
1829 week, so this returns 2 for Monday.
1830 • c
1832 The numeric day of the week from 1 to 7, treating Monday as the
1834 first of the week, regardless of locale.
1835 • ccc
1837 The abbreviated stand-alone form for the day of the week.
1839 • cccc
1841 The wide stand-alone form for the day of the week.
1843 • ccccc
1845 The narrow format form for the day of the week.
1847 • a
1849 The localized form of AM or PM for the time.
1851 • h{1,2}
1853 The hour from 1-12.
1855 • H{1,2}
1857 The hour from 0-23.
1859 • K{1,2}
1861 The hour from 0-11.
1863 • k{1,2}
1865 The hour from 1-24.
1867 • j{1,2}
1869 The hour, in 12 or 24 hour form, based on the preferred form for
1871 the locale. In other words, this is equivalent to either "h{1,2}"
1872 or "H{1,2}".
1873 • m{1,2}
1875 The minute.
1877 • s{1,2}
1879 The second.
1881 • S{1,}
1883 The fractional portion of the seconds, rounded based on the length
1885 of the specifier. This returned without a leading decimal point,
1886 but may have leading or trailing zeroes.
1887 • A{1,}
1889 The millisecond of the day, based on the current time. In other
1891 words, if it is 12:00:00.00, this returns 43200000.
1892 • z{1,3}
1894 The time zone short name.
1896 • zzzz
1898 The time zone long name.
1900 • Z{1,3}
1902 The time zone offset.
1904 • ZZZZ
1906 The time zone short name and the offset as one string, so something
1908 like "CDT-0500".
1909 • ZZZZZ
1911 The time zone offset as a sexagesimal number, so something like
1913 "-05:00". (This is useful for W3C format.)
1914 • v{1,3}
1916 The time zone short name.
1918 • vvvv
1920 The time zone long name.
1922 • V{1,3}
1924 The time zone short name.
1926 • VVVV
1928 The time zone long name.
1930 CLDR "Available Formats"
1932 The CLDR data includes pre-defined formats for various patterns such as
1934 "month and day" or "time of day". Using these formats lets you render
1935 information about a datetime in the most natural way for users from a
1936 given locale.
1937 These formats are indexed by a key that is itself a CLDR pattern. When
1939 you look these up, you get back a different CLDR pattern suitable for
1940 the locale.
1941 Let's look at some example We'll use "2008-02-05T18:30:30" as our
1943 example datetime value, and see how this is rendered for the "en-US"
1944 and "fr-FR" locales.
1945 • "MMMd"
1947 The abbreviated month and day as number. For "en-US", we get the
1949 pattern "MMM d", which renders as "Feb 5". For "fr-FR", we get the
1950 pattern "d MMM", which renders as "5 févr.".
1951 • "yQQQ"
1953 The year and abbreviated quarter of year. For "en-US", we get the
1955 pattern "QQQ y", which renders as "Q1 2008". For "fr-FR", we get
1956 the same pattern, "QQQ y", which renders as "T1 2008".
1957 • "hm"
1959 The 12-hour time of day without seconds. For "en-US", we get the
1961 pattern "h:mm a", which renders as "6:30 PM". For "fr-FR", we get
1962 the exact same pattern and rendering.
1963 The available formats for each locale are documented in the POD for
1965 that locale. To get back the format, you use the "$locale->format_for"
1966 method. For example:
1967 say $dt->format_cldr( $dt->locale->format_for('MMMd') );
1969 strftime Patterns
1971 The following patterns are allowed in the format string given to the
1972 "$dt->strftime" method:
1973 • %a
1975 The abbreviated weekday name.
1977 • %A
1979 The full weekday name.
1981 • %b
1983 The abbreviated month name.
1985 • %B
1987 The full month name.
1989 • %c
1991 The default datetime format for the object's locale.
1993 • %C
1995 The century number (year/100) as a 2-digit integer.
1997 • %d
1999 The day of the month as a decimal number (range 01 to 31).
2001 • %D
2003 Equivalent to %m/%d/%y. This is not a good standard format if you
2005 want folks from both the United States and the rest of the world to
2006 understand the date!
2007 • %e
2009 Like %d, the day of the month as a decimal number, but a leading
2011 zero is replaced by a space.
2012 • %F
2014 Equivalent to %Y-%m-%d (the ISO 8601 date format)
2016 • %G
2018 The ISO 8601 year with century as a decimal number. The 4-digit
2020 year corresponding to the ISO week number (see %V). This has the
2021 same format and value as %Y, except that if the ISO week number
2022 belongs to the previous or next year, that year is used instead.
2023 (TZ)
2024 • %g
2026 Like %G, but without century, i.e., with a 2-digit year (00-99).
2028 • %h
2030 Equivalent to %b.
2032 • %H
2034 The hour as a decimal number using a 24-hour clock (range 00 to
2036 23).
2037 • %I
2039 The hour as a decimal number using a 12-hour clock (range 01 to
2041 12).
2042 • %j
2044 The day of the year as a decimal number (range 001 to 366).
2046 • %k
2048 The hour (24-hour clock) as a decimal number (range 0 to 23);
2050 single digits are preceded by a blank. (See also %H.)
2051 • %l
2053 The hour (12-hour clock) as a decimal number (range 1 to 12);
2055 single digits are preceded by a blank. (See also %I.)
2056 • %m
2058 The month as a decimal number (range 01 to 12).
2060 • %M
2062 The minute as a decimal number (range 00 to 59).
2064 • %n
2066 A newline character.
2068 • %N
2070 The fractional seconds digits. Default is 9 digits (nanoseconds).
2072 %3N milliseconds (3 digits)
2074 %6N microseconds (6 digits)
2075 %9N nanoseconds (9 digits)
2076 This value will always be rounded down to the nearest integer.
2078 • %p
2080 Either `AM' or `PM' according to the given time value, or the
2082 corresponding strings for the current locale. Noon is treated as
2083 `pm' and midnight as `am'.
2084 • %P
2086 Like %p but in lowercase: `am' or `pm' or a corresponding string
2088 for the current locale.
2089 • %r
2091 The time in a.m. or p.m. notation. In the POSIX locale this is
2093 equivalent to `%I:%M:%S %p'.
2094 • %R
2096 The time in 24-hour notation (%H:%M). (SU) For a version including
2098 the seconds, see %T below.
2099 • %s
2101 The number of seconds since the epoch.
2103 • %S
2105 The second as a decimal number (range 00 to 61).
2107 • %t
2109 A tab character.
2111 • %T
2113 The time in 24-hour notation (%H:%M:%S).
2115 • %u
2117 The day of the week as a decimal, range 1 to 7, Monday being 1. See
2119 also %w.
2120 • %U
2122 The week number of the current year as a decimal number, range 00
2124 to 53, starting with the first Sunday as the first day of week 01.
2125 See also %V and %W.
2126 • %V
2128 The ISO 8601:1988 week number of the current year as a decimal
2130 number, range 01 to 53, where week 1 is the first week that has at
2131 least 4 days in the current year, and with Monday as the first day
2132 of the week. See also %U and %W.
2133 • %w
2135 The day of the week as a decimal, range 0 to 6, Sunday being 0. See
2137 also %u.
2138 • %W
2140 The week number of the current year as a decimal number, range 00
2142 to 53, starting with the first Monday as the first day of week 01.
2143 • %x
2145 The default date format for the object's locale.
2147 • %X
2149 The default time format for the object's locale.
2151 • %y
2153 The year as a decimal number without a century (range 00 to 99).
2155 • %Y
2157 The year as a decimal number including the century.
2159 • %z
2161 The time-zone as hour offset from UTC. Required to emit
2163 RFC822-conformant dates (using "%a, %d %b %Y %H:%M:%S %z").
2164 • %Z
2166 The short name for the time zone, typically an abbreviation like
2168 "EST" or "AEST".
2169 • %%
2171 A literal `%' character.
2173 • %{method}
2175 Any method name may be specified using the format "%{method}" name
2177 where "method" is a valid "DateTime" object method.
2178 DateTime and Storable
2180 "DateTime" implements Storable hooks in order to reduce the size of a
2181 serialized "DateTime" object.
2182
2184 This module is part of a larger ecosystem of modules in the DateTime
2185 family.
2186 DateTime::Set
2188 The DateTime::Set module represents sets (including recurrences) of
2189 datetimes. Many modules return sets or recurrences.
2190 Format Modules
2192 The various format modules exist to parse and format datetimes. For
2193 example, DateTime::Format::HTTP parses dates according to the RFC 1123
2194 format:
2195 my $datetime
2197 = DateTime::Format::HTTP->parse_datetime(
2198 'Thu Feb 3 17:03:55 GMT 1994');
2199 print DateTime::Format::HTTP->format_datetime($datetime);
2201 Most format modules are suitable for use as a "formatter" with a
2203 DateTime object.
2204 All format modules start with DateTime::Format::
2206 <https://metacpan.org/search?q=datetime%3A%3Aformat>.
2207 Calendar Modules
2209 There are a number of modules on CPAN that implement non-Gregorian
2210 calendars, such as the Chinese, Mayan, and Julian calendars.
2211 All calendar modules start with DateTime::Calendar::
2213 <https://metacpan.org/search?q=datetime%3A%3Acalendar>.
2214 Event Modules
2216 There are a number of modules that calculate the dates for events, such
2217 as Easter, Sunrise, etc.
2218 All event modules start with DateTime::Event::
2220 <https://metacpan.org/search?q=datetime%3A%3Aevent>.
2221 Others
2223 There are many other modules that work with DateTime, including modules
2224 in the DateTimeX namespace <https://metacpan.org/search?q=datetimex>
2225 namespace, as well as others.
2226 See MetaCPAN <https://metacpan.org/search?q=datetime> for more modules.
2228
2230 The tests in 20infinite.t seem to fail on some machines, particularly
2231 on Win32. This appears to be related to Perl's internal handling of
2232 IEEE infinity and NaN, and seems to be highly platform/compiler/phase
2233 of moon dependent.
2234 If you don't plan to use infinite datetimes you can probably ignore
2236 this. This will be fixed (perhaps) in future versions.
2237
2239 A Date with Perl <http://www.houseabsolute.com/presentations/a-date-
2240 with-perl/> - a talk I've given at a few YAPCs.
2241 datetime@perl.org mailing list
2243 <http://lists.perl.org/list/datetime.html>
2244 <http://datetime.perl.org/>
2246
2248 Bugs may be submitted at
2249 <https://github.com/houseabsolute/DateTime.pm/issues>.
2250 There is a mailing list available for users of this distribution,
2252 <mailto:datetime@perl.org>.
2253 I am also usually active on IRC as 'autarch' on "irc://irc.perl.org".
2255
2257 The source code repository for DateTime can be found at
2258 <https://github.com/houseabsolute/DateTime.pm>.
2259
2261 If you'd like to thank me for the work I've done on this module, please
2262 consider making a "donation" to me via PayPal. I spend a lot of free
2263 time creating free software, and would appreciate any support you'd
2264 care to offer.
2265 Please note that I am not suggesting that you must do this in order for
2267 me to continue working on this particular software. I will continue to
2268 do so, inasmuch as I have in the past, for as long as it interests me.
2269 Similarly, a donation made in this way will probably not make me work
2271 on this software much more, unless I get so many donations that I can
2272 consider working on free software full time (let's all have a chuckle
2273 at that together).
2274 To donate, log into PayPal and send money to autarch@urth.org, or use
2276 the button at <https://www.urth.org/fs-donation.html>.
2277
2279 Dave Rolsky <autarch@urth.org>
2280
2282 • Ben Bennett <fiji@limey.net>
2283 • Christian Hansen <chansen@cpan.org>
2285 • Daisuke Maki <dmaki@cpan.org>
2287 • Dan Book <grinnz@gmail.com>
2289 • Dan Stewart <danielandrewstewart@gmail.com>
2291 • David E. Wheeler <david@justatheory.com>
2293 • David Precious <davidp@preshweb.co.uk>
2295 • Doug Bell <madcityzen@gmail.com>
2297 • Flávio Soibelmann Glock <fglock@gmail.com>
2299 • Gianni Ceccarelli <gianni.ceccarelli@broadbean.com>
2301 • Gregory Oschwald <oschwald@gmail.com>
2303 • Hauke D <haukex@zero-g.net>
2305 • Iain Truskett <deceased>
2307 • Jason McIntosh <jmac@jmac.org>
2309 • Joshua Hoblitt <jhoblitt@cpan.org>
2311 • Karen Etheridge <ether@cpan.org>
2313 • Mark Overmeer <mark@overmeer.net>
2315 • Michael Conrad <mike@nrdvana.net>
2317 • Michael R. Davis <mrdvt92@users.noreply.github.com>
2319 • Mohammad S Anwar <mohammad.anwar@yahoo.com>
2321 • M Somerville <dracos@users.noreply.github.com>
2323 • Nick Tonkin <1nickt@users.noreply.github.com>
2325 • Olaf Alders <olaf@wundersolutions.com>
2327 • Ovid <curtis_ovid_poe@yahoo.com>
2329 • Paul Howarth <paul@city-fan.org>
2331 • Philippe Bruhat (BooK) <book@cpan.org>
2333 • philip r brenan <philiprbrenan@gmail.com>
2335 • Ricardo Signes <rjbs@cpan.org>
2337 • Richard Bowen <bowen@cpan.org>
2339 • Ron Hill <rkhill@cpan.org>
2341 • Sam Kington <github@illuminated.co.uk>
2343 • viviparous <viviparous@prc>
2345
2347 This software is Copyright (c) 2003 - 2020 by Dave Rolsky.
2348 This is free software, licensed under:
2350 The Artistic License 2.0 (GPL Compatible)
2352 The full text of the license can be found in the LICENSE file included
2354 with this distribution.
2355perl v5.32.1 2021-01-27 DateTime(3)