1DateTime::Precise(3) User Contributed Perl Documentation DateTime::Precise(3)
2
6 DateTime::Precise - Perform common time and date operations with
7 additional GPS operations
8
10 use DateTime::Precise;
11 use DateTime::Precise qw(:TimeVars);
13 # Constructors and ways to set time.
15 $t1 = DateTime::Precise->new;
16 $t2 = DateTime::Precise->new('1998. 4. 3 12:13:44.054');
17 $t3 = DateTime::Precise->new(time() - 100.23456);
18 $t4 = DateTime::Precise->new('1998.04.24');
19 $t1->set_localtime_from_epoch_time;
20 $t1->set_gmtime_from_epoch_time(time + 120.987);
21 $t1->set_from_datetime('1998.03.23 16:58:14.65');
22 $t1->set_time('YDHMS', 1998, 177, 9, 15, 26.5);
23 # This is the same as $d3->set_from_datetime(...)
25 $t3->dscanf("%^Y.%M.%D %h:%m:%s", "1998.03.25 20:25:23");
26 if ($msg = $d1->dscanf("%~M", $input)) {
27 print "error: $msg\n";
28 print "Must enter a three-letter month abbrev.\n";
29 }
30 # Get different parts of the time.
32 $year = $t3->year;
33 $month = $t3->month;
34 $day = $t3->day;
35 $hours = $t3->hours;
36 $minutes = $t3->minutes;
37 $seconds = $t3->seconds;
38 ($year, $day_of_year) = $t3->get_time('Yj');
39 # Print times and dates.
41 print $t2->asctime;
42 print $t2->strftime('%T %C%n');
43 print $t2->dprintf("%^Y.%M.%D %h:%m:%s"); # datetime
44 print $t2->dprintf("%~w %~M %-D %h:%m:%s CST %^Y"); # ctime
45 # Copy times.
47 my $t4 = $t2->copy;
48 # Set one time object to the same time as another: set $t3 equal to $t2.
50 $t3->clone($t2);
51 # Find the difference between two times.
53 $secs_from_midnight = $t4 - $t1;
54 $secs_from_midnight = $t4->diff($t1);
55 # Add seconds, days, months, etc to time.
57 $t1 = $t4 + 3600; # $t1 is now an hour after midnight
58 $t1->inc_month(2); # add two months to $t1
59 $t1->floor_month; # set $t1 to the first of the month
60 $t1 -= 0.25; # subtract 1/4 of a second from $t1
61 # Can compare and sort DateTime::Precise.
63 print "It's late!!!" if ($t1 > $t4);
64 @sorted = sort @birthdays; # normal comparisons work fine
65 # Get the GPS weeks, seconds and day.
67 $gps_week = $t1->gps_week;
68 $gps_seconds = $t1->gps_seconds;
69 $gps_day = $t1->gps_day;
70 ($gps_week, $gps_seconds, $gps_day) = $t1->gps_week_seconds_day;
71
73 The purpose of this library was to replace our dependence on Unix epoch
74 time, which, being limited to a range of about 1970 to 2030, is
75 inadequate for our purposes (we have data as old as 1870). This date
76 library effectively handles dates from A.D. 1000 to infinity, and would
77 probably work all the way back to 0 (ignoring, of course, the switch-
78 over to the Gregorian calendar). The useful features of Unix epoch
79 time (ease of date difference calculation and date comparison, strict
80 ordering) are preserved, and elements such as human-legibility are
81 added. The library handles fractional seconds and some date/time
82 manipulations used for the Global Positioning Satellite system.
83 The operators +/-, <=>, cmp, stringify are overloaded. Addition
85 handles seconds and fractions of seconds, subtraction handles seconds
86 or date differences, compares work, and stringification returns the a
87 representation of the date.
88 The US Geological Survey (USGS) likes midnight to be 24:00:00 of the
90 previous day, not 00:00:00 of the day people expect. If
91 $DateTime::Precise::USGSMidnight is set, dprintf will always print
92 midnight as 24:00:00 and the date returned from dprintf will have the
93 previous day's date. Regardless, time is always stored internally as
94 00:00:00.
95
97 new
98 new('1998. 4. 3 12:13:44')
99 new(time() - 100.23456)
100 new('YDHMS', 1998, 200, 13, 16, 49.5)
101 This creates a new time object. If no argument is passed, then the
102 time object is initialized with the time returned from gmtime
103 (time()). The second form is used to set the time explicitly. The
104 argument can be in one of three formats: "YYYY.MM.DD
105 hh:mm:ss.ffff", "YYYY.MM.DD" (midnight assumed), or
106 "YYYYMMDDhhmmss.ffff". Here ffff are the fractions of seconds.
107 The third form sets the time using gmtime() with fractional seconds
108 allowed. The fourth form sets the time using a format as the first
109 argument followed by the particular date adjustments as the
110 following arguments. See set_time() for more information. If the
111 new fails, then new returns an empty list in a list context, an
112 undefined value in a scalar context, or nothing in a void context.
113 Because the second and third forms pass only one argument to new(),
115 there must be a way of distinguishing them. Currently the
116 following test is used: if any non-digit characters are found in
117 the argument or if the string form of the argument is longer than
118 10 character, then assume it to be a string to parse for the date.
119 Otherwise it is the time since the Unix epoch. The string length
120 of 10 was chosen since when the Unix epoch time flips to 11 digits,
121 it'll be roughly year 2287.
122
124 set_from_datetime datetime
125 Set date/time from passed date/time string "YYYY.MM.DD
126 hh:mm:ss.fff". If set_from_datetime successfully parses datetime,
127 then the newly set date/time object is returned, otherwise it
128 returns an empty list in a list context, an undefined value in a
129 scalar context, or nothing in a void context.
130 set_localtime_from_epoch_time [epoch]
132 Set from epoch time into the local time zone. If epoch is passed,
133 then use that time to set the current time, otherwise use the time
134 as returned from time() or from Time::HiRes::time() if the
135 Time::HiRes module can be loaded. If the Time::HiRes::time() can
136 be imported, then the resulting loaded time most likely will
137 contain a fractional second component. The newly set date/time
138 object is returned. The epoch can contain fractional seconds.
139 set_gmtime_from_epoch_time [epoch]
141 Set from the epoch time into the standard Greenwich time zone. If
142 epoch is passed, then use that time to set the current time,
143 otherwise use the time as returned from time() or from
144 Time::HiRes::time() if the Time::HiRes module can be loaded. If
145 the Time::HiRes::time() can be imported, then the resulting loaded
146 time most likely will contain a fractional second component. The
147 newly set date/time object is returned. The epoch can contain
148 fractional seconds.
149 set_from_day_of_year year day_of_year
151 Set date/from from the year and the decimal day of the year.
152 Midnight January 1st is day 1, noon January 1st is 1.5, etc. If
153 the date was successfully set, then the newly set date/time object
154 is returned, otherwise it returns an empty list in a list context,
155 an undefined value in a scalar context, or nothing in a void
156 context.
157 set_from_serial_day serial_day_number
159 Set the date/time from the serial day. See also serial_day(). If
160 the date was successfully set, then the newly set date/time object
161 is returned, otherwise is returns an empty list in a list context,
162 an undefined value in a scalar context, or nothing in a void
163 context.
164 set_from_gps_week_seconds gps_week gps_seconds
166 Set the current time using the number of weeks and seconds into the
167 week since GPS epoch (January 6, 1980 UTC). If the date was
168 successfully set, then the newly set date/time object is returned,
169 otherwise is returns an empty list in a list context, an undefined
170 value in a scalar context, or nothing in a void context.
171 set_time format [arg, [arg, ...]]
173 Set the time. format is a string composed of a select set of
174 characters. Some characters may take an optional argument, which
175 are listed following the format argument in the same order as the
176 characters. The first character must be an absolute time:
177 N => Set time to now. No argument taken.
179 G => Set time to GPS time 0 (January 6, 1980). No argument taken.
180 Y => Set time to beginning of the year. Argument taken.
181 J => Set time to modified Julian date. Argument taken.
182 s => Set time to seconds since January 1, 1970. Argument taken.
183 These characters represent modifiers to the time set using the
185 above characters:
186 B => Add months to time. Argument taken.
188 W => Add weeks to time. Argument taken.
189 D => Add days counted from 1 to time. Argument taken.
190 d => Add days counted from 0 to time. Argument taken.
191 H => Add hours to time. Argument taken.
192 M => Add minutes to time. Argument taken.
193 S => Add seconds to time. Argument taken.
194 If the date and time was successfully set, then it returns the
196 newly set date/time object, otherwise set_time() returns an empty
197 list in a list context, an undefined value in a scalar context, or
198 nothing in a void context and the date and time remain unchanged.
199 get_time string
201 Return an array, where each element of the array corresponds to the
202 corresponding strftime() value. This string should not contain %
203 characters. This method is a much, much better and faster way of
204 doing
205 map {$self->strftime("%$_")} split(//, $string)
207 year [year]
209 Return the year. If an argument is passed to year, then set the
210 year to the the integer part of the argument and then return the
211 newly set year.
212 month [month]
214 Return the numerical month (1 = January, 12 = December). If an
215 argument is passed to month, then set the month to the integer part
216 of the argument and return the newly set month.
217 day [day]
219 Return the day of the month. If an argument is passed to day, then
220 set the day to the integer part of the argument and return the
221 newly set day.
222 hours [hours]
224 Return the hours in the day. If an argument is passed to hours,
225 then set the hours to the integer part of the argument and return
226 the newly set hours.
227 minutes [minutes]
229 Return the minutes in the hour. If an argument is passed to
230 minutes, then set the minutes to the integer part of the argument
231 and return the newly set minutes.
232 seconds [seconds]
234 Return the seconds in the minutes. If an argument is passed to
235 seconds, then set the seconds to the argument and return the newly
236 set seconds. This argument accepts fractional seconds and will
237 return the fractional seconds.
238 serial_day
240 Returns a serial day number representing the date, plus a fraction
241 representing the time since midnight (i.e., noon=0.5). This is for
242 applications which need an scale index (we use it for positioning a
243 date on a time-series graph axis). See also set_from_serial_day().
244 day_of_year
246 Return the day of the year including the fraction part of the day.
247 Midnight January 1st is day 1, noon January 1st is 1.5, etc.
248 julian_day
250 Return the day of the year including the fraction part of the day
251 where time is 0 based. Midnight January 1st is day 0, noon January
252 1st is 0.5, noon January 2nd is 1.5, etc.
253 unix_seconds_since_epoch
255 Return the time in seconds between the object and January 1, 1970
256 UTC.
257 gps_seconds_since_epoch
259 Return the time in seconds between the object and January 6, 1980
260 UTC.
261 gps_week_seconds_day
263 Return an array consisting of the GPS week 0 filled to four spaces,
264 the number of seconds into the GPS week, and the GPS day, where day
265 0 is Sunday.
266 gps_week
268 Return the GPS week of the object. The returned number is 0 filled
269 to four digits.
270 gps_seconds
272 Return the number of seconds into the current GPS week for the
273 current object.
274 gps_day
276 Return the GPS day of the week for the current object, where day 0
277 is Sunday.
278 copy
280 Return an identical copy of the current object.
281 clone other_dt
283 Set this DateTime::Precise equal to other_dt.
284 dprintf string
286 Returns string with substitutions:
287 %x number zero-padded to 2 digits (ie, '02')
289 %C<-x> number space-padded to 2 digits (ie, ' 2')
290 %^x unpadded number (ie, '2')
291 %~x 3-letter abbrev corresponding to value (%M and %w only)
292 %*x full name corresponding to value (%M and %w only)
293 %% '%'
294 where x is one of:
296 h hours (0..23)
298 m minutes (0..59)
299 s seconds (0..59)
300 D day of the month (1..31)
301 M month (1..12)
302 Y years since 1900 (ie, 96)
303 W USGS water year (year+1 for months Oct-Dec)
304 w day of the week (0..6, or "Mon", etc.)
305 E internal string (no ~^*-)
306 so, for example, to get a string in datetime format, you would pass
308 a string of '%^Y.%M.%D %h:%m:%s', or, to get a ctime-like string,
309 you would pass: '%~w %~M %-D %h:%m:%s CDT %^Y' (presuming you're in
310 the CDT. Maybe timezone support will show up some day).
311 The US Geological Survey (USGS) likes midnight to be 24:00:00 of
313 the previous day, not 00:00:00 of the day people expect. If
314 $DateTime::Precise::USGSMidnight is set, dprintf will always print
315 midnight as 24:00:00 and the date returned from dprintf will have
316 the previous day's date. Regardless, time is always stored
317 internally as 00:00:00.
318 dscanf format string
320 Takes a format string format, and use it to read the date and time
321 fields from the supplied string. The current date and time is
322 unchanged if dscanf fails.
323 All format characters recognized by dprintf() are valid. Two
325 additional characters are recognized, 'U' which sets the time to
326 the local time/date using the number of seconds since Unix epoch
327 time and 'u' which sets the time to GMT time/date using the number
328 of seconds since Unix epoch time. Unless exact characters are
329 supplied or format characters are concatenated, will separate on
330 non-matching characters.
331 strftime format
333 Just like the strftime() function call. This version is based on
334 the Solaris manual page. format is a string containing of zero or
335 more conversion specifications. A specification character consists
336 of a '%' (percent) character followed by one conversion characters
337 that determine the conversion specifications behavior. All
338 ordinary characters are copied unchanged to the return string.
339 The following GPS specific conversions are supported in this
341 strftime:
342 %s the seconds since UTC January 1, 1970
343 %G the GPS week (4 digits with leading 0's)
344 %g the GPS seconds into the GPS week with no leading zeros
345 %f the GPS day where 0 = Sunday, 1 = Monday, etc
346 %F the GPS day where 1 = Sunday, 2 = Monday, etc
347 The following standard conversions are understood:
349 %% the same as %
351 %a the abbreviated weekday name
352 %A the full weekday name
353 %b the abbreviated month name
354 %B the full month name
355 %c the appropriate date and time representation
356 %C century number (the year divided by 100 and truncated to an
357 integer as a decimal number [1,99]); single digits are
358 preceded by 0
359 %d day of month [1,31]; single digits are preceded by 0
360 %D date as %m/%d/%y
361 %e day of month [1,31]; single digits are preceded by a space
362 %h locale's abbreviated month name
363 %H hour (24-hour clock) [0,23]; single digits are preceded by 0
364 %I hour (12-hour clock) [1,12]; single digits are preceded by 0
365 %j day number of year [1,366]; single digits are preceded by 0
366 %k hour (24-hour clock) [0,23]; single digits are preceded by
367 a blank
368 %l hour (12-hour clock) [1,12]; single digits are preceded by
369 a blank
370 %m month number [1,12]; single digits are preceded by 0
371 %M minute [00,59]; leading zero is permitted but not required
372 %n insert a newline
373 %p either AM or PM
374 %r appropriate time representation in 12-hour clock format with
375 %p
376 %R time as %H:%M
377 %S seconds [00,61]
378 %t insert a tab
379 %T time as %H:%M:%S
380 %u weekday as a decimal number [1,7], with 1 representing Sunday
381 %U week number of year as a decimal number [00,53], with Sunday
382 as the first day of week 1
383 %V week number of the year as a decimal number [01,53], with
384 Monday as the first day of the week. If the week containing 1
385 January has four or more days in the new year, then it is
386 considered week 1; otherwise, it is week 53 of the previous
387 year, and the next week is week 1.
388 %w weekday as a decimal number [0,6], with 0 representing Sunday
389 %W week number of year as a decimal number [00,53], with Monday
390 as the first day of week 1
391 %x locale's appropriate date representation
392 %X locale's appropriate time representation
393 %y year within century [00,99]
394 %Y year, including the century (for example 1993)
395 %Z Always GMT
396 asctime
398 Return a string such as 'Fri Apr 3 12:13:44 GMT 1998'. This is
399 equivalent to strftime('%c').
400 Incrementing and rounding
402 There are many subroutines of the format 'func_unit', where func is one
403 of (inc, dec, floor, ceil, round) and unit is one of (second, minute,
404 hour, day, month, year) [second and minute can be abbreviated as sec
405 and min respectively].
406 inc_unit(i) increments the date by i units (i defaults to 1 if no
408 parameter is supplied). For days through seconds, fractional
409 increments are allowed. However, for months and years, only the
410 integer part of the increment is used.
411 dec_unit(i) identical to inc_unit("-i").
413 round_unit() rounds the date to the nearest unit. Rounds years down
415 for Jan-Jun, and up for Jul-Dec; months down for 1st-15th and up for
416 16th and later; days round up on or after 12:00:00; hours on or after
417 xx:30:00, minutes on or after 30 seconds; seconds on or after 0.5
418 seconds.
419 floor_unit() rounds the date down to the earliest time for the current
421 unit. For example, floor_month() rounds to midnight of the first day
422 of the current month, floor_day() to midnight of the current day, and
423 floor_hour() to xx:00:00.
424 ceil_unit() is the complementary function to floor. It rounds the date
426 up, to the earliest time in the next unit. E.g., ceil_month() makes
427 the date midnight of the first day of the next month.
428 Overloaded operators
430 Addition, subtraction, and comparison operators are overloaded, as well
431 as the string representation of a date object.
432 # create a new object
434 $x = DateTime::Precise->new('1996.05.05 05:05:05');
435 # copy it
436 $y = $x;
437 # increment x by one second
438 $x++;
439 # decrement by a day
440 $y = $y - 86400;
441 # test em
442 print ($x < $y ? "x is earlier\n" : "y is earlier\n");
443 # get the difference
444 print "The difference between x and y is ", $x-$y, " seconds.\n";
445 If $x is a date object, "$x + $i" is identical to $x->inc_sec($i).
447 There are two possible results from subtraction. "$x - $i", where $i
449 is a number, will return a new date, $i seconds before $x. "$x - $y",
450 where $y is another date object, is identical to $x->diff($y).
451 Comparison operators (<,>,==,etc) work as one would expect.
453
455 The following variables are not imported into your package by default.
456 If you want to use them, then use
457 use DateTime::Precise qw(:TimeVars);
459 in your package. Otherwise, you can use the fully qualified package
461 name, such as $DateTime::Precise::USGSMidnight.
462 $USGSMidnight
464 Set this to 1 if you want midnight represented as 24:00:00 of the
465 previous day. The default value is 0 which does not change the
466 behavior of midnight. To use this variable in your code, load the
467 DateTime::Precise module like this:
468 use DateTime::Precise qw($USGSMidnight);
470 Setting this only changes the output of dprintf for date and times
472 that are exactly midnight.
473 @MonthDays
475 Days per month in a non-leap year. This array is 1 indexed, so 0
476 is December, 1 is January, etc.
477 @MonthName
479 Month names. This array is 1 indexed, so 0 is December, 1 is
480 January, etc.
481 @MonthAbbrev
483 Month abbreviated names. This array is 1indexed, so 0 is Dec, 1 is
484 Jan, etc.
485 @WeekName
487 Names of the week, 0 indexed. So 0 is Sunday, 1 is Monday, etc.
488 @WeekAbbrev
490 Abbreviated names of the week, 0 indexed. So 0 is Sun, 1 is Mon,
491 etc.
492 &Secs_per_week
494 The number of seconds in one week (604800).
495 &Secs_per_day
497 The number of seconds in one day (86400).
498 &Secs_per_hour
500 The number of seconds in one hour (3600).
501 &Secs_per_minute
503 The number of seconds in one minute (60).
504 &JANUARY_1_1970
506 Subroutine returning the Unix epoch time January 1, 1970 UTC.
507 &JANUARY_6_1980
509 Subroutine returning the GPS epoch time January 6, 1980 UTC.
510
512 IsLeapYear(year)
513 Returns true if the argument is a leap year.
514 DaysInMonth(month, year)
516 Returns the number of days in the month.
517
519 This package is based on the DateTime package written by Greg Fast
520 <gdfast@usgs.gov>. The _week_of_year routine is based on the
521 Date_WeekOfYear routine from the Date::DateManip package written by
522 Sullivan Beck.
523 Instead of using the string representation used in the original
525 DateTime package, this package represents the time internally as a
526 seven element array, where the elements correspond to the year, month,
527 day, hours, minutes, seconds, and fractional seconds.
528
530 Contact: Blair Zajac <blair@orcaware.com>. The original version of
531 this module was based on DateTime written by Greg Fast
532 <gdfast@usgs.gov>.
533
535 Hey! The above document had some coding errors, which are explained
536 below:
537 Around line 2024:
539 =back doesn't take any parameters, but you said =back 4
540 Around line 2330:
542 =back doesn't take any parameters, but you said =back 4
543 Around line 2398:
545 '=item' outside of any '=over'
546 Around line 2457:
548 You forgot a '=back' before '=head1'
549 Around line 2469:
551 =back doesn't take any parameters, but you said =back 4
552perl v5.36.0 2023-01-20 DateTime::Precise(3)