-- Randal L. Schwartz, Perl hacker

He said (and I think he meant) 5 to 10 FIVE digit zip codes. And I think he was just going to hard code those zip codes in the script. So perhaps something like:

#!/usr/local/bin/perl -l -w

use strict;
use CGI;

my @zips = qw(
    92714
    92715
    92716
);

my %zips;
@zips{@zips} = ();

my $q = CGI->new;

print $q->header;
print $q->start_html;

if (my $zip = $q->param('zip')) {
 print "<br>You entered $zip";
 my $valid = (exists $zips{$zip}) ? 'valid' : 'invalid';
 print "<br>It is $valid";
} else {
 print $q->start_form;
 print $q->textfield(-name=>"zip");
 print $q->submit("Go");
 print $q->end_form;
}

print $q->end_html;
[download]

Update: Ok, so you can get rid of the hash and replace 'exists $zip{$zips}' with 'grep { $_ eq $zip } @zips' (see my benchmarks further down this thread), although if you were to port this to mod_perl or the like I'd stick with a hash (though it'd be defined differently) :-)

Even in this script, there's no point in building the hash. A linear scan over @zips would have been more efficient.

-- Randal L. Schwartz, Perl hacker

Randal has a point...

However, I see a use for a hash in the form of

%hash{$zip$;service}
[download]

foreach $ourzips (@zipcodes) {
     if ($userzip eq $ourzips) {
          $service = %hash{$userzip, service} ;
     } else {
          $service = "No service available. Loooooser!" ;
     }
}
[download]