Well, you could use a regex to URL encode all the elements in your URL parameters, then join them together into a single query string.

But, there is a much simpler way, using the CPAN module URI.

Below is an example program using URI that does something similar to what you want:

#!/usr/bin/perl -w

use strict;
use URI;

use constant BASE_URL => 'index.pl';
use constant REFERER  => 'http://search.cpan.org/search?dist=URI';

my $uri = URI->new(BASE_URL);

$uri->query_form(
  location => 'Redirect',
  URL      => REFERER,
  referer  => 'Links',
);

print $uri;
[download]

A well formed URL will be printed out, and any parameters will be URL encoded properly.

A nice bonus is that the code made with URI is easy to read and hides all the potentially messy URL construction/encoding details from you. I almost never work with URL's by hand any longer since I started to use this module.