1Time::Piece(3pm) Perl Programmers Reference Guide Time::Piece(3pm)
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6 Time::Piece - Object Oriented time objects
7
9 use Time::Piece;
10 my $t = localtime;
12 print "Time is $t\n";
13 print "Year is ", $t->year, "\n";
14
16 This module replaces the standard localtime and gmtime functions with
17 implementations that return objects. It does so in a backwards
18 compatible manner, so that using localtime/gmtime in the way documented
19 in perlfunc will still return what you expect.
20 The module actually implements most of an interface described by Larry
22 Wall on the perl5-porters mailing list here:
23 http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/2000-01/msg00241.html
24
26 After importing this module, when you use localtime or gmtime in a
27 scalar context, rather than getting an ordinary scalar string
28 representing the date and time, you get a Time::Piece object, whose
29 stringification happens to produce the same effect as the localtime and
30 gmtime functions. There is also a new() constructor provided, which is
31 the same as localtime(), except when passed a Time::Piece object, in
32 which case it's a copy constructor. The following methods are available
33 on the object:
34 $t->sec # also available as $t->second
36 $t->min # also available as $t->minute
37 $t->hour # 24 hour
38 $t->mday # also available as $t->day_of_month
39 $t->mon # 1 = January
40 $t->_mon # 0 = January
41 $t->monname # Feb
42 $t->month # same as $t->monname
43 $t->fullmonth # February
44 $t->year # based at 0 (year 0 AD is, of course 1 BC)
45 $t->_year # year minus 1900
46 $t->yy # 2 digit year
47 $t->wday # 1 = Sunday
48 $t->_wday # 0 = Sunday
49 $t->day_of_week # 0 = Sunday
50 $t->wdayname # Tue
51 $t->day # same as wdayname
52 $t->fullday # Tuesday
53 $t->yday # also available as $t->day_of_year, 0 = Jan 01
54 $t->isdst # also available as $t->daylight_savings
55 $t->hms # 12:34:56
57 $t->hms(".") # 12.34.56
58 $t->time # same as $t->hms
59 $t->ymd # 2000-02-29
61 $t->date # same as $t->ymd
62 $t->mdy # 02-29-2000
63 $t->mdy("/") # 02/29/2000
64 $t->dmy # 29-02-2000
65 $t->dmy(".") # 29.02.2000
66 $t->datetime # 2000-02-29T12:34:56 (ISO 8601)
67 $t->cdate # Tue Feb 29 12:34:56 2000
68 "$t" # same as $t->cdate
69 $t->epoch # seconds since the epoch
71 $t->tzoffset # timezone offset in a Time::Seconds object
72 $t->julian_day # number of days since Julian period began
74 $t->mjd # modified Julian date (JD-2400000.5 days)
75 $t->week # week number (ISO 8601)
77 $t->is_leap_year # true if it its
79 $t->month_last_day # 28-31
80 $t->time_separator($s) # set the default separator (default ":")
82 $t->date_separator($s) # set the default separator (default "-")
83 $t->day_list(@days) # set the default weekdays
84 $t->mon_list(@days) # set the default months
85 $t->strftime(FORMAT) # same as POSIX::strftime (without the overhead
87 # of the full POSIX extension)
88 $t->strftime() # "Tue, 29 Feb 2000 12:34:56 GMT"
89 Time::Piece->strptime(STRING, FORMAT)
91 # see strptime man page. Creates a new
92 # Time::Piece object
93 Local Locales
95 Both wdayname (day) and monname (month) allow passing in a list to use
96 to index the name of the days against. This can be useful if you need
97 to implement some form of localisation without actually installing or
98 using locales.
99 my @days = qw( Dimanche Lundi Merdi Mercredi Jeudi Vendredi Samedi );
101 my $french_day = localtime->day(@days);
103 These settings can be overriden globally too:
105 Time::Piece::day_list(@days);
107 Or for months:
109 Time::Piece::mon_list(@months);
111 And locally for months:
113 print localtime->month(@months);
115 Date Calculations
117 It's possible to use simple addition and subtraction of objects:
118 use Time::Seconds;
120 my $seconds = $t1 - $t2;
122 $t1 += ONE_DAY; # add 1 day (constant from Time::Seconds)
123 The following are valid ($t1 and $t2 are Time::Piece objects):
125 $t1 - $t2; # returns Time::Seconds object
127 $t1 - 42; # returns Time::Piece object
128 $t1 + 533; # returns Time::Piece object
129 However adding a Time::Piece object to another Time::Piece object will
131 cause a runtime error.
132 Note that the first of the above returns a Time::Seconds object, so
134 while examining the object will print the number of seconds (because of
135 the overloading), you can also get the number of minutes, hours, days,
136 weeks and years in that delta, using the Time::Seconds API.
137 In addition to adding seconds, there are two APIs for adding months and
139 years:
140 $t->add_months(6);
142 $t->add_years(5);
143 The months and years can be negative for subtractions. Note that there
145 is some "strange" behaviour when adding and subtracting months at the
146 ends of months. Generally when the resulting month is shorter than the
147 starting month then the number of overlap days is added. For example
148 subtracting a month from 2008-03-31 will not result in 2008-02-31 as
149 this is an impossible date. Instead you will get 2008-03-02. This
150 appears to be consistent with other date manipulation tools.
151 Date Comparisons
153 Date comparisons are also possible, using the full suite of "<", ">",
154 "<=", ">=", "<=>", "==" and "!=".
155 Date Parsing
157 Time::Piece has a built-in strptime() function (from FreeBSD), allowing
158 you incredibly flexible date parsing routines. For example:
159 my $t = Time::Piece->strptime("Sunday 3rd Nov, 1943",
161 "%A %drd %b, %Y");
162 print $t->strftime("%a, %d %b %Y");
164 Outputs:
166 Wed, 03 Nov 1943
168 (see, it's even smart enough to fix my obvious date bug)
170 For more information see "man strptime", which should be on all unix
172 systems.
173 Alternatively look here:
175 http://www.unix.com/man-page/FreeBSD/3/strftime/
176 YYYY-MM-DDThh:mm:ss
178 The ISO 8601 standard defines the date format to be YYYY-MM-DD, and the
179 time format to be hh:mm:ss (24 hour clock), and if combined, they
180 should be concatenated with date first and with a capital 'T' in front
181 of the time.
182 Week Number
184 The week number may be an unknown concept to some readers. The ISO
185 8601 standard defines that weeks begin on a Monday and week 1 of the
186 year is the week that includes both January 4th and the first Thursday
187 of the year. In other words, if the first Monday of January is the
188 2nd, 3rd, or 4th, the preceding days of the January are part of the
189 last week of the preceding year. Week numbers range from 1 to 53.
190 Global Overriding
192 Finally, it's possible to override localtime and gmtime everywhere, by
193 including the ':override' tag in the import list:
194 use Time::Piece ':override';
196
198 Setting $ENV{TZ} in Threads on Win32
199 Note that when using perl in the default build configuration on Win32
200 (specifically, when perl is built with PERL_IMPLICIT_SYS), each perl
201 interpreter maintains its own copy of the environment and only the main
202 interpreter will update the process environment seen by strftime.
203 Therefore, if you make changes to $ENV{TZ} from inside a thread other
205 than the main thread then those changes will not be seen by strftime if
206 you subsequently call that with the %Z formatting code. You must change
207 $ENV{TZ} in the main thread to have the desired effect in this case
208 (and you must also call _tzset() in the main thread to register the
209 environment change).
210 Furthermore, remember that this caveat also applies to fork(), which is
212 emulated by threads on Win32.
213 Use of epoch seconds
215 This module internally uses the epoch seconds system that is provided
216 via the perl "time()" function and supported by "gmtime()" and
217 "localtime()".
218 If your perl does not support times larger than "2^31" seconds then
220 this module is likely to fail at processing dates beyond the year 2038.
221 There are moves afoot to fix that in perl. Alternatively use 64 bit
222 perl. Or if none of those are options, use the DateTime module which
223 has support for years well into the future and past.
224
226 Matt Sergeant, matt@sergeant.org Jarkko Hietaniemi, jhi@iki.fi (while
227 creating Time::Piece for core perl)
228
230 This module is free software, you may distribute it under the same
231 terms as Perl.
232
234 The excellent Calendar FAQ at
235 http://www.tondering.dk/claus/calendar.html
236
238 The test harness leaves much to be desired. Patches welcome.
239perl v5.16.3 2013-03-04 Time::Piece(3pm)