Date formatting in Perl - perl

I have a variable which contain value "20140720". I need to change it to the format "20/07".
My code is shown below.
#!/usr/bin/perl
use strict;
use warnings;
use Time::Piece;
my $date = '20140720';
my $date_format = Time::Piece->strptime($date, '%d/%m');
my $new_date = $date_format->strftime('%d/%m');
print $new_date;
I get following error during execution.
Error parsing time at /usr/lib/perl5/5.10.0/x86_64-linux-thread-multi/Time/Piece.pm line 470.

In this line — Time::Piece->strptime($date, '%d/%m'); — you specified the format that $date is currently in incorrectly. The second argument describes how the string should be parsed, not the format you want it to be in (which is what the following line is for).
Use '%Y%m%d' instead.

With a fixed string, you should use the pack/unpack function:
use strict;
use warnings;
my $date = '20140720';
my (undef, $m, $d) = unpack 'A4A2A2', $date;
print "$d/$m";

If you don't need further date processing, using a simple regular expression may be simpler:
use strict;
use warnings;
my $date = '20140720';
my $new_date = $date;
$new_date =~ s!\d{4}(\d{2})(\d{2})$!$2/$1!;
print $new_date, "\n";

Related

Perl: Getting weeknumbers from pre-formatted date-time strings

I am getting date-time strings in the format "2021-04-25 04:27:35" (YYYY-MM-DD hh:mm:ss) and need to convert them to "2021w18".
I must get the weeknumber and I already have the below in my perl script.
use Time::Piece;
use POSIX qw(strftime);
Any help will help me progress beyond "newbie".
Here's a subroutine that will do what you want:
use Time::Piece;
use POSIX qw(strftime);
use strict;
use warnings;
use feature 'say';
sub dateToWeek {
my ($date) = #_;
my $t = Time::Piece->strptime($date, "%Y-%m-%d %H:%M:%S");
return $t->strftime("%Yw%U");
}
say dateToWeek("2021-04-25 04:27:35");
Output:
2021w17
Pass it a date contained in a string and it will return the year + "w" + week number.
If you need it to return 2021w18 instead of 2021w17 for April 25, 2021, change the return statement to add 1 to the strftime like so:
return $t->year . "w" . ($t->strftime("%U")+1);

Date::Manip::Delta - the number of seconds [duplicate]

The code below only expresses the difference in months and days like so:
0:2:0:5:0:0:0
So it works, but I want to know the total number of days given that $ADDate can vary quite a bit. Hopefully this is simple, and I just completely missed how to do it.
#!/usr/bin/perl
use Date::Manip 6.42;
my $ADDate = "20131211000820.0Z";
my $var;
my #val;
my $diff;
calc_period($ADDate = "20131211000820.0Z");
sub calc_period
{
$ADDate =~ s/^([\d][\d][\d][\d])([\d][\d])([\d][\d])/$1-$2-$3/gs;
$ADDate =~ s/.........$//gs;
$today = ParseDate("today");
$beginning = ParseDate($ADDate);
$end = ParseDate($today);
$delta = DateCalc($beginning,$end,\$err,1);
#$delta =~ s/([\d+][:][\d+]):.*$/$1/gs;
print "$delta\n";
print "$ADDate\n";
}
I'm not familiar with Date::Manip, but I think another way to do this is to use Time::Piece to parse your string and do whatever you like with that since taking the difference of two Time::Piece object returns a Time::Seconds object.
The following example will show the difference of the current time and the hardcoded time and show it in days.
#!/usr/bin/perl
use strict;
use warnings;
use Time::Piece;
use Time::Seconds;
my $d = "20131211000820.0Z";
my $t = Time::Piece->strptime($d, "%Y%m%d%H%M%S.0Z");
my $now = Time::Piece->localtime();
my $diff = Time::Seconds->new($now - $t);
print $diff->days, "\n";
NigoroJr has already given you an answer. However, just as an FYI, the following is how I would clean up the code you originally provided:
#!/usr/bin/perl
use Date::Manip 6.42;
use strict;
use warnings;
calc_period("20131211000820.0Z");
sub calc_period {
my $date = shift;
$date =~ s/^(\d{4})(\d{2})(\d{2}).*/$1-$2-$3/;
my $beginning = ParseDate($date);
my $end = ParseDate("today");
my $delta = DateCalc($beginning, $end, \my $err, 1);
#$delta =~ s/([\d+][:][\d+]):.*$/$1/gs;
print "$delta\n";
print "$date\n";
}
Biggest differences being the proper use of a function and scoped variables, and a simplification of your regex.
I was unable to find a clean way to get Date::Manip to output a strict delta in days though, so the other module is the way to go.

How do I get last year date and current date using perl?

I want to fetch current date and exactly last year date using perl in the format of 140220 and 130220.
Perhaps the following will help:
use strict;
use warnings;
use Time::Piece;
my $time = Time::Piece->new;
my $currDate = $time->strftime('%y%m%d');
print $currDate, "\n";
my $lastYear = $time->add_years(-1)->strftime('%y%m%d');
print $lastYear;
Output:
140219
130219
Here is a sample using DateTime.
#!/usr/bin/env perl
use strict;
use warnings;
use feature qw/say/;
use DateTime;
my $dt = DateTime->now();
my $year_ago = DateTime->now()->subtract(years => 1);
say $dt->strftime("%y%m%d");
say $year_ago->strftime("%y%m%d");

Today's Date in Perl in MM/DD/YYYY format

I'm working on a Perl program at work and stuck on (what I think is) a trivial problem. I simply need to build a string in the format '06/13/2012' (always 10 characters, so 0's for numbers less than 10).
Here's what I have so far:
use Time::localtime;
$tm=localtime;
my ($day,$month,$year)=($tm->mday,$tm->month,$tm->year);
You can do it fast, only using one POSIX function. If you have bunch of tasks with dates, see the module DateTime.
use POSIX qw(strftime);
my $date = strftime "%m/%d/%Y", localtime;
print $date;
You can use Time::Piece, which shouldn't need installing as it is a core module and has been distributed with Perl 5 since version 10.
use Time::Piece;
my $date = localtime->strftime('%m/%d/%Y');
print $date;
output
06/13/2012
Update
You may prefer to use the dmy method, which takes a single parameter which is the separator to be used between the fields of the result, and avoids having to specify a full date/time format
my $date = localtime->dmy('/');
This produces an identical result to that of my original solution
use DateTime qw();
DateTime->now->strftime('%m/%d/%Y')
expression returns 06/13/2012
If you like doing things the hard way:
my (undef,undef,undef,$mday,$mon,$year) = localtime;
$year = $year+1900;
$mon += 1;
if (length($mon) == 1) {$mon = "0$mon";}
if (length($mday) == 1) {$mday = "0$mday";}
my $today = "$mon/$mday/$year";
use Time::Piece;
...
my $t = localtime;
print $t->mdy("/");# 02/29/2000
Perl Code for Unix systems:
# Capture date from shell
my $current_date = `date +"%m/%d/%Y"`;
# Remove newline character
$current_date = substr($current_date,0,-1);
print $current_date, "\n";
Formating numbers with leading zero is done easily with "sprintf", a built-in function in perl (documentation with: perldoc perlfunc)
use strict;
use warnings;
use Date::Calc qw();
my ($y, $m, $d) = Date::Calc::Today();
my $ddmmyyyy = sprintf '%02d.%02d.%d', $d, $m, $y;
print $ddmmyyyy . "\n";
This gives you:
14.05.2014

How can I parse a strftime formatted string in Perl?

I am new to Perl and I wan to know whether there is an inverse function to the strftime().
Look,
use POSIX qw(strftime);
print strftime("%YT%mT%d TTTT%H:%M:%S", localtime)
I get: 2009T08T14 TTTT00:37:02. How can I do the oposite operation? From "2009T08T14 TTTT00:37:02" string to get 2009-08-14 00:37:02, knowing the formatting string "%YT%mT%d TTTT%H:%M:%S"?
One option is to parse the numbers using a regular expression and then use Time::Local. However, now that I understand your question is how to go from a strftime formatted string to a time in general, that approach is bound to be cumbersome.
You mention in your answer POSIX::strptime which is great if your platform supports it. Alternatively, you can use DateTime::Format::Strptime:
#!/usr/bin/perl
use strict;
use warnings;
use DateTime::Format::Strptime;
use POSIX qw(strftime);
my $f = "%YT%mT%d TTTT%H:%M:%S";
my $s = strftime($f, localtime);
print "$s\n";
my $Strp = DateTime::Format::Strptime->new(
pattern => $f,
locale => 'en_US',
time_zone => 'US/Eastern',
);
my $dt = $Strp->parse_datetime($s);
print $dt->epoch, "\n";
print scalar localtime $dt->epoch, "\n";
$dt is a DateTime object so you can do pretty much whatever you want with it.
I think I have found the solution: strptime($strptime_pattern, $string)
So easyy
use Time::ParseDate;
my $t = '2009T08T14 TTTT00:37:02';
$t =~ s/TTTT//;
$t =~ s/T/-/g;
$seconds_since_jan1_1970 = parsedate($t)