use CGI::Carp qw/fatalsToBrowser/;
[download]

use Data::Dumper::Simple;
print q(<pre>);
print Dumper(%foo);
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my @params = param();
print q(<pre>);
for (@params) {
    print "$_ :: $params[$_]\n";
}
[download]

Hope this helps,
Darren :)

For development, I even use:

use CGI::Carp qw/fatalsToBrowser warningsToBrowser/;

because it also handles warnings

Update: is wrong, see the posting from reneeb below

Best regards,
perl -e "s>>*F>e=>y)\*martinF)stronat)=>print,print v8.8.8.32.11.32"

To handle warnings, you have to call the warningsToBrowser subroutine with a true argument. See documentation of CGI::Carp.

Just a note:
warningsToBrowser(1) must be explicitly called after printing the page header, and will output all warnings as HTML comments. It's its difference from fatalsToBrowser, which catches all fatal errors (even compile-time!) without any additional actions. The CGI::Carp documentation contains additional info.

UPD: i haven't seen the previous reply while writing this :)

In addition to the excellent advice you've already got from McDarren it's worth pointing out that CGI::Carp is a very useful module for getting nicely formatted error messages out of a CGI program. In particular, I recommend the "carpout" function which allows you to set up an alternative log file that CGI::Carp messages get written to.

You should also be aware that a CGI program really isn't that much different to any other Perl program and you don't need to run it on a web server. As long as the required inputs are set up, you can run a CGI program from the command line. I've debugged many a problematic CGI program using Perl's built-in debugger.