#!/usr/bin/perl

use warnings;
use strict;
use CGI;

my $q       = CGI->new;
my $num     = $q->param ('num') || 1;
my $button  = $q->param ('go'); 

## increment $num if clicked in "Add"
$num++ if (defined $button and 'Set' ne $button);

print
    $q->header ('text/html'),
    $q->start_html,
    "paragraph 1: num is [$num]",
    $q->start_form,
        $q->popup_menu (-name => 'num', -values => [1 .. 3], -default => $num),
        $q->textfield (-name => 'foo', -value => "num is [$num]"),
        $q->submit (-name => 'go', -value => 'Set'), 
        $q->submit (-name => 'go', -value => 'Add'), 
    $q->end_form,
    "paragraph 2: num is [$num]",
    $q->end_html;