If you're using CGI.pm (and you should be when doing most CGI work), you can retrieve the list of all CGI parameters by using:

my @fields = param;

Or you can access a value individually by using:

my $single_item = param( 'item[123]' );

Or print out all params and their values by using:

print join br, map { "$_ = " . param( $_ ) } param();

If you're not using CGI.pm, you can do so easily by adding use CGI qw/ :standard /; at the top of your program. Documentation for CGI.pm is here.