• There are Date and Time modules on CPAN. Some of them are particularly suited to managing date ranges.
• You could play with times by adding seconds to the epoch clock, but you'd need to be aware of many issues the date and time modules handle for you.
• You can use the unary increment operator (++) on a value of 80623 and format the printing how you want, but you'd have to roll over the months and days with a nasty collection of case or if statements. You'd still also need to handle many issues the date and time modules handle for you.
• There are probably even worse ways to handle this, and we could probably have a contest to see how perverse a working solution could be.

If you search the PM site, you'll probably find some great comparisons and advice about date and time modules as well. One should do what you need.

Update: s/data/date/ in the second list item.

I never stated that I was proposing to us this format (yymmdd) over the 8 digits. I am simply trying to use data that has already been formatted by someone else. The format shouldn't be a problem because it is only used to name text files that are less than a year old.

Also, you stated that there are worse ways to do this....……what are some better ways? Why not have a contest to create the best solution?

You want a better way than other people writing more than a dozen modules you can choose from to do your work? What's better than that, other than someone actually writing your code for you?

The dates could be compared alphabetically. For example, '080801' is alphabetically less than '080812'. So, in the code below, the 'ge' and 'le' string comparison operators could be used to filter out the dates contained in the file name.

#!/usr/bin/perl
use strict;
use warnings;

my $path = "/some/path";
my $name = "name";
my $start = "$path/080801_$name";
my $end = "$path/080930_$name";

for my $file (grep {$_ ge $start && $_ le $end} glob "$path/??????_$na
+me") {
    open my $fh, "<", $file or die "unable to open $file";
    while (<$fh>) {
        # process...
    }
    close $fh or die "unable to close $file";
}
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Update: Changed glob "$path/????_$name to glob "$path/??????_$name to correctly let the wildcard operator, '?', match the 6 chars in the date portion of the file name.

my $date_string = sprintf('%02d%02d%02d', $year-1900, $month, $day);
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Of course you meant:

my $date_string = sprintf('%02d%02d%02d', $year%100, $month, $day);
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Which just illustrates why this is such a bad date format to use

#!/usr/bin/perl
use strict;
use warnings;
use Date::Simple 'ymd';

for (my $date=ymd(2008,8,1), my $end=ymd(2008,9,30);$date <= $end; $da
+te++) {
    my $file = $date->format("%y%m%d_name");
    warn("$file: no such file\n"), next unless -e $file;
    open IN, "<", $file or die "Unable to open $file";
    while (<IN>) {
        # ... process
    }
    close IN or die "Unable to close $file";
}
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#!/usr/bin/perl

use strict;
use warnings;

use Date::Manip;

my $start_date_str = '080225';
my $end_date_str   = '080304';

my $std_start_date_str = join( '-', substr($start_date_str, 0,2 ), sub
+str($start_date_str, 2) );
my $std_end_date_str   = join( '-', substr($end_date_str, 0,2 ),   sub
+str($end_date_str, 2) );

my $current_dt = ParseDate( $std_start_date_str);
my $end_dt     = ParseDate( $std_end_date_str);

while( $current_dt le $end_dt) {
    my $display_date_str = UnixDate( $current_dt, '%y%m%d' );
    print "$display_date_str\n";
    $current_dt = DateCalc( $current_dt, '+ 1 day');
}
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