Re: converting dates to epoch seconds and back

2013-01-18 Thread John W. Krahn 

Bill Stephenson wrote:

When converting DMYHMS to Epoch Seconds and back I get cheated out of a day. 
Why?

Bill

--

#!/usr/bin/perl

use strict;
use warnings;
use Time::Local;

my ($time, $month, $day, $year, $seconds, $minutes, $hours, $wday, $yday, 
$isdst);

my $start_date = '11/30/2012';

print "$start_date \n";

($month, $day, $year) = split(/\//, $start_date);

print $time = timegm($seconds, $minutes, $hours, $day, $month-1, $year-1900);

^^
**



print "\n";

($seconds, $minutes, $hours, $day, $month, $year, $wday, $yday, $isdst) = 
localtime($time);


 ^

 *




$month++;

$year = ($year+1900);

print "$month/$day/$year \n";

# output:
# 11/30/2012
# 1354233600
# 11/29/2012


You are using GMT for one conversion and local time for the other.  Best 
to use GMT for both conversions:


$ perl -le'
use strict;
use warnings;
use Time::Local;

my ( $time, $month, $day, $year, $seconds, $minutes, $hours );
my $start_date = q[11/30/2012];
print $start_date;
( $month, $day, $year ) = split /\//, $start_date;
print $time = timegm( $seconds, $minutes, $hours, $day, $month - 1, 
$year - 1900 );

( $seconds, $minutes, $hours, $day, $month, $year ) = gmtime $time;
$month++;
$year += 1900;
print "$month/$day/$year";
'
11/30/2012
1354233600
11/30/2012




John
--
Any intelligent fool can make things bigger and
more complex... It takes a touch of genius -
and a lot of courage to move in the opposite
direction.   -- Albert Einstein

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Re: converting dates to epoch seconds and back

2013-01-18 Thread Dominik Danter 
The output depends on the timezone that you have set on your machine. You can
toy around and try different ones with
$ENV{TZ} = 'Europe/Vienna'; or
$ENV{TZ} = 'America/Los_Angeles';

If you don't want to depend on the timezone use gmtime instead of localtime.

Bill Stephenson  hat am 18. Januar 2013 um 21:13
geschrieben:
> When converting DMYHMS to Epoch Seconds and back I get cheated out of a day.
> Why?
>
> Bill
>
> --
>
> #!/usr/bin/perl
>
> use strict;
> use warnings;
> use Time::Local;
>
> my ($time, $month, $day, $year, $seconds, $minutes, $hours, $wday, $yday,
> $isdst);
>
> my $start_date = '11/30/2012';
>
> print "$start_date \n";
>
> ($month, $day, $year) = split(/\//, $start_date);
>
> print $time = timegm($seconds, $minutes, $hours, $day, $month-1, $year-1900);
>
> print "\n";
>
> ($seconds, $minutes, $hours, $day, $month, $year, $wday, $yday, $isdst) =
> localtime($time);
>
> $month++;
>
> $year = ($year+1900);
>
> print "$month/$day/$year \n";
>
> # output:
> # 11/30/2012
> # 1354233600
> # 11/29/2012
> --
> To unsubscribe, e-mail: beginners-unsubscr...@perl.org
> For additional commands, e-mail: beginners-h...@perl.org
> http://learn.perl.org/
>
>

---

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Dominik Danter

RE: converting dates to epoch seconds and back

2013-01-18 Thread twlewis 
Bill, it appears to have to do with it pick the time not being populated, and 
it picking up the date from yesterday.

I added some lines to test this theory.  Try running the code below without an 
argument, and then with an argument.

Tim


#!/usr/bin/perl

use strict;
use warnings;
use Time::Local;

my ($time, $month, $day, $year, $seconds, $minutes, $hours, $wday, $yday, 
$isdst);

my $start_date = '11/30/2012';

print "$start_date \n";

($month, $day, $year) = split(/\//, $start_date);

#Added this to populate the time
if (defined($ARGV[0])) {
  print "Populating the time\n";
  $seconds = 30;
  $minutes = 30;
  $hours = 11;
}

print $time = timegm($seconds, $minutes, $hours, $day, $month-1, $year-1900);

print "\n";

($seconds, $minutes, $hours, $day, $month, $year, $wday, $yday, $isdst) = 
localtime($time);

$month++;

$year = ($year+1900);

print "$month/$day/$year \n";



-Original Message-
From: "Bill Stephenson" 
Sent: Friday, January 18, 2013 3:13pm
To: "Perl Beginners" 
Subject: converting dates to epoch seconds and back

When converting DMYHMS to Epoch Seconds and back I get cheated out of a day. 
Why?

Bill

--

#!/usr/bin/perl

use strict;
use warnings;
use Time::Local;

my ($time, $month, $day, $year, $seconds, $minutes, $hours, $wday, $yday, 
$isdst);

my $start_date = '11/30/2012';

print "$start_date \n";

($month, $day, $year) = split(/\//, $start_date);

print $time = timegm($seconds, $minutes, $hours, $day, $month-1, $year-1900);

print "\n";

($seconds, $minutes, $hours, $day, $month, $year, $wday, $yday, $isdst) = 
localtime($time);

$month++;

$year = ($year+1900);

print "$month/$day/$year \n";

# output:
# 11/30/2012 
# 1354233600
# 11/29/2012
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converting dates to epoch seconds and back

2013-01-18 Thread Bill Stephenson 
When converting DMYHMS to Epoch Seconds and back I get cheated out of a day. 
Why?

Bill

--

#!/usr/bin/perl

use strict;
use warnings;
use Time::Local;

my ($time, $month, $day, $year, $seconds, $minutes, $hours, $wday, $yday, 
$isdst);

my $start_date = '11/30/2012';

print "$start_date \n";

($month, $day, $year) = split(/\//, $start_date);

print $time = timegm($seconds, $minutes, $hours, $day, $month-1, $year-1900);

print "\n";

($seconds, $minutes, $hours, $day, $month, $year, $wday, $yday, $isdst) = 
localtime($time);

$month++;

$year = ($year+1900);

print "$month/$day/$year \n";

# output:
# 11/30/2012 
# 1354233600
# 11/29/2012
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