I have a paltry, date string conundrum upon which I beseech the wisdom of those who frequent this site. I am doing basic date/string manipulation with the constraint of not using Date::Calc; I am just using Perl "out of the box". The below code snippet demonstrates the core issue. I take an input date and generate a date 6 days later. It works for every date except November 1st and I am not sure why. 
#!/usr/bin/perl -w
use warnings;
use strict;
use Getopt::Long;
use Time::Local;
use POSIX qw(strftime);

# The idea is to take an input date and add 6 days to it.
# It seems to work except when the start date is November 1!
#
# Below is an example:
#

my $input_date;
GetOptions("start_date=s" => \$input_date);
print "\nWe expect a start day and a day 6 days later than that!\n";
my @date_pieces = split('/',$input_date);
  
my $start_day = timelocal(0, 0, 0, $date_pieces[1], $date_pieces[0]-1,
+ $date_pieces[2]);
my $end_day = $start_day + 6*24*60*60;

my $new_start_day = strftime "%m/%d/%Y", (localtime($start_day));
my $new_end_day = strftime "%m/%d/%Y", (localtime($end_day));

print "The start day is $new_start_day and the end day is $new_end_day
+\n";

[download]
Below is a run of various inputs and you see that the only failure seen is Nov 1st: 
$ LIST="09/20/2008 1/1/2009 11/3/2008 06/06/2006 11/1/2008 11/1/2008 1
+0/1/2008"
$ for i in $LIST
> do
> booger -start_date $i
> done

We expect a start day and a day 6 days later than that!
The start day is 09/20/2008 and the end day is 09/26/2008

We expect a start day and a day 6 days later than that!
The start day is 01/01/2009 and the end day is 01/07/2009

We expect a start day and a day 6 days later than that!
The start day is 11/03/2008 and the end day is 11/09/2008

We expect a start day and a day 6 days later than that!
The start day is 06/06/2006 and the end day is 06/12/2006

We expect a start day and a day 6 days later than that!
The start day is 11/01/2008 and the end day is 11/06/2008

We expect a start day and a day 6 days later than that!
The start day is 11/01/2008 and the end day is 11/06/2008

We expect a start day and a day 6 days later than that!
The start day is 10/01/2008 and the end day is 10/07/2008

[download]
Note how both November dates are 5 days apart as opposed to 6. Any help would be greatly appreciated.

In reply to date string conundrum by Anonymous Monk

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