Time::Piece and localtime?

slugger415 has asked for the wisdom of the Perl Monks concerning the following question:

Hello, I have a script using Time::Piece that compares dates/times to localtime. I am getting some unexpected behavior which I've tracked to a 7 hour difference in time zones (I'm on the U.S. west coast).

My snippet:

use Time::Piece;
use Time::Seconds;
use strict;

my $dateformat = "%H:%M:%S, %m/%d/%Y";

my $date1 = "11:56:00, 09/17/2022";
my $date2 = "14:31:00, 09/16/2022";
my $date3 = "11:20:00, 09/13/2022";

my $t = localtime;
print "Current time: \n", $t, $/,$/;

$date1 = Time::Piece->strptime($date1, $dateformat);
$date2 = Time::Piece->strptime($date2, $dateformat);
$date3 = Time::Piece->strptime($date3, $dateformat);

my(@ds) = ($date1,$date2,$date3);

foreach my $dt (@ds){
    print $dt, $/;
    if($dt < $t){
        print " in the past...\n";
    }
    else{
        print " in the future...\n";
    }
}
[download]

This results in:

Current time:
Fri Sep 16 07:39:44 2022

Sat Sep 17 11:56:00 2022
 in the future...
Fri Sep 16 14:31:00 2022
 in the past...
Tue Sep 13 11:20:00 2022
 in the past...
[download]

As you can see the 2nd date for Fri Sep 16 should be "in the future...". If I change $t to gmtime I get the behavior I want, but I don't want to use gmtime for comparison. Is there a way to do this with localtime? Thank you.

Comment on Time::Piece and localtime? Select or Download Code

Replies are listed 'Best First'.
Re: Time::Piece and localtime? by choroba (Cardinal) on Sep 16, 2022 at 16:07 UTC
If you don't supply the timezone to `strptime`, it uses UTC. `localtime` always knows its timezone, though. One of the ways how to construct the object in the current zone is to use `localtime` to construct the object instead of the class: `$date1 = localtime->strptime($date1, $dateformat);` [download] `map{substr$_->[0],$_->[1]\|\|0,1}[\\|\|{},3],[[]],[ref qr-1,-,-1],[{}],[sub{}^ARGV,3]`	[reply] [d/l] [select]
Re^2: Time::Piece and localtime? by slugger415 (Monk) on Sep 16, 2022 at 17:30 UTC
that worked, thank you!	[reply]
Re: Time::Piece and localtime? by Corion (Patriarch) on Sep 16, 2022 at 15:42 UTC
Time::Piece has no idea what timezone your parsed times are in. Maybe you can supply a time zone offset using the `->tzoffset` method? Or alternatively, add the appropriate timezone to your parsed string and the format?	[reply] [d/l]
Re^2: Time::Piece and localtime? by slugger415 (Monk) on Sep 16, 2022 at 17:36 UTC
how is `tzoffset` used? I don't see any description of that. Thanks.	[reply] [d/l]