I have come to love the DateTime modules for this kind of work. They're lean, offer a clean interface, and allow you to do just about anything you'd ever want to, without much hassle (so long as you don't mind occasionally reading the docs).

If you want a sledgehammer solution, try Date::Manip — its original intent was to let people enter complex time specifications like "second Wednesday this month" on the commandline and have them work. It's rather heavy and the author himself discourages its use for more narrowly defined scenarios, though.

The DateTime project is supposed to make all other Perl date and time handling modules obsolete and replace them with a consistant set of modules.

To do what you want with the DateTime modules, you'd use DateTime::Format::Strptime like this:

#!/usr/bin/perl

use strict;
use warnings;

use DateTime::Format::Strptime;

my $str = '20031105';

my $parser = DateTime::Format::Strptime->new(pattern => '%Y%m%d');

my $dt = $parser->parse_datetime($str);

$dt->add(months => 3);

# standard date format
print $dt->date, "\n";
# or in your original formay
print $parser->format_datetime($dt), "\n";
[download]