date and time difference

invisiblehand has asked for the wisdom of the Perl Monks concerning the following question:

(perl version 5.8.7)

I have two date strings and and try to calculate date and time difference between two dates and times.

But the difference looks incorrect, could you help me to get the correct value?

notBefore=Nov 23 22:31:12 2019 GMT

notAfter=Mar 19 06:52:23 2020 GMT

#!/usr/bin/perl
use Time::Local;

# FILE READ IN
$log_file = './raw.txt';
open(FH, '<',  $log_file) or die $!;

while (<FH>) {
 if(m/START/) {chomp; $sdname = $_;}
 if(m/notBefore/) {
   chomp; ($notB1, $notB2) = split('=', $_);
   $notB2 =~ tr/:/ /;
   my($mon,$mday,$hour,$minute,$sec,$year)=split(/ /,$notB2);
   #print $mon, $mday, $hour, $minute, $sec, $year;
   $time_1 = timelocal($sec,$minute,$hour,$mday,$mon,$year);
 }
 if(m/notAfter/) {
   chomp; ($notA1, $notA2) = split('=', $_);
   $notA2 =~ tr/:/ /;
   my($mon,$mday,$hour,$minute,$sec,$year)=split(/ /,$notA2);
   $time_2 = timelocal($sec,$minute,$hour,$mday,$mon,$year);
 }
 if(m/END/) {printf("%s %s %s\n", $sdname, $notB2, $notA2);
   print $time_2,"\n",$time_1, "\n";
   $diff_time = $time_2 - $time_1;
   $diff_time1 = ($diff_time/86400);
   print "diff_time :$diff_time:$diff_time1:\n";
 }
}
[download]

===output=====

SD0101START Nov 23 22 31 12 2019 GMT Mar 19 06 52 23 2020 GMT

1579384343

1548250272

diff_time :31134071:360.348043981481:

========rax.txt===========

SD0101START

notBefore=Nov 23 22:31:12 2019 GMT

notAfter=Mar 19 06:52:23 2020 GMT

SD0101END

SD0201START

notBefore=Nov 24 11:11:11 2019 GMT

notAfter=Mar 19 06:52:23 2020 GMT

SD0201END

Comment on date and time difference Download Code

Replies are listed 'Best First'.
Re: date and time difference by haukex (Archbishop) on Jan 08, 2020 at 14:10 UTC
`timelocal` requires the month as a number, you're giving it a string, which is being interpreted as `0` (January). You can see this with a `print gmtime($time_1)."\n";`. You'd need to convert it from string to number first. Also, since your times are in GMT, you should use `timegm` instead. Note that the Time::Local docs strongly recommend to use `timegm_modern` instead. And personally I'd strongly recommend you switch to a better module, such as Time::Piece, which has a `strptime` method to parse strings directly, or DateTime with DateTime::Format::Strptime. Also, your version of Perl if about 15 years old, I would strongly recommend looking into upgrading.	[reply] [d/l] [select]
Re^2: date and time difference by invisiblehand (Initiate) on Jan 08, 2020 at 15:19 UTC
Oh, thanks a lot, it worked well after change the Nov to 11 as you recommended. And thanks for your concern for using old version, but I can't not upgrade. It is not my authority. Please I have another question more. 1. My time zone is KST(South Korea republic), but when I executed following command in my system(openbsd),I got GMT time. In this case, Can I change the output GMT to KST?	[reply]
Re^3: date and time difference by haukex (Archbishop) on Jan 08, 2020 at 15:23 UTC
My time zone is KST(South Korea republic), but when I executed following command in my system(openbsd),I got GMT time. Which command do you mean? If you mean Perl's output, gmtime will give you GMT, and localtime will give you whatever the current time zone setting on that machine is. If you want more advanced functionality than that, then you need to switch to DateTime. And thanks for your concern for using old version, but I can't not upgrade. It is not my authority. Similar advice as in Yes, even you can use CPAN applies.	[reply]
Re^4: date and time difference by invisiblehand (Initiate) on Jan 08, 2020 at 17:55 UTC
Re^5: date and time difference by haukex (Archbishop) on Jan 08, 2020 at 19:20 UTC
Some notes below your chosen depth have not been shown here
Re^3: date and time difference by ikegami (Patriarch) on Jan 08, 2020 at 16:51 UTC
Nov is 10, actually. The month number is 0-based (for consistency with `localtime`).	[reply] [d/l]
Re: date and time difference by 1nickt (Canon) on Jan 08, 2020 at 15:10 UTC
Hi, your technique is ancient, unreliable and unnecessarily complicated. DateTime::Format::Strptime is the right tool as haukex has noted. Read the documentation about date math carefully. Here's an example using `subtract_datetime()`: `$ perl -Mstrict -MData::Dumper -MDateTime::Format::Strptime -wE 'my $p + = DateTime::Format::Strptime->new(pattern => "%b %d %T %Y %Z", on_er +ror => "croak"); my ($dt1, $dt2) = map { $p->parse_datetime($_) } ("N +ov 23 22:31:12 2019 GMT", "Mar 19 06:52:23 2020 GMT"); say for ($dt2, + $dt1); say sprintf("%s : %s", $_, $dt2->subtract_datetime($dt1)->{$_ +}) for qw/months days minutes seconds/'` [download] `2020-03-19T06:52:23 2019-11-23T22:31:12 months : 3 days : 25 minutes : 501 seconds : 11` [download] You can of course express the delta however you choose, using the correct method calls. Hope this helps! The way forward always starts with a minimal test.	[reply] [d/l] [select]
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