peppiv has asked for the wisdom of the Perl Monks concerning the following question:

Problem: I'm trying to increment the value of a variable with the push of a form button. I would like the value to increment by 10 every time I push the button. I'm apparently brain dead today because I can't figure this simple problem out. Please help!

I think we can do this with only a snippet.

my $limit_3 = param("limit_3");
my $limit = param("limit");
my $add_limit = ($limit_3 + $limit);
my $limit = ($limit_3 + 0);

print qq($limit);

<form method="POST" action="add_to_the_number.pl"><input type="hidden"
+ name="limit_3" value="10"><input type="hidden" name="limit" value="$
+limit"><input type="submit" name="action" value="Next"></form>

[download]

$limit starts at 0 - Perfect!
One push of the button and $limit = 10. - Perfect again!
Another push of the button and $limit = 20. Again Perfect!
Yet another push of the button and $limit still = 20.
Every subsequent push and the value continues to remain at 20. I would like it to increment by 10 EVERY time I push the button. Where am I failing?

peppiv

if ($date = $today) {$brain = $mush}

Replies are listed 'Best First'.
(jeffa) Re: Increment Number with form button push
by jeffa (Bishop) on Jun 13, 2002 at 19:48 UTC
    You are never updating the variable to be carried over. First, $add_limit is unecessary, just do this instead: 
    my $limit_3 = param("limit_3");
my $limit = param("limit");
$limit = ($limit_3 + $limit);

print $limit; # and rest of form

    [download]
    Now, when you write out the hidden field, it will contain the current value. Before, you were writing out $limit to the hidden field without changing it's initial value, which was always 0.

    Here is some more code to meditate upon: 

    use strict;
use CGI qw(:standard);

my $i = param('hidden_i') || 0;
my @view = qw(
   first second third   fourth
   fifth sixth  seventh eighth
);

my $view = $view[$i++];

param('hidden_i',$i % @view);

print header, 
   start_html('hidden fields'),
      h1($view),
      start_form,
         hidden('hidden_i'),
         submit,
      end_form,
   end_html,
;

    [download]

    jeffa

    L-LL-L--L-LL-L--L-LL-L--
-R--R-RR-R--R-RR-R--R-RR
B--B--B--B--B--B--B--B--
H---H---H---H---H---H---
(the triplet paradiddle with high-hat)
[reply]
[d/l]
[select]
      Ah Yes! This works!
      If I wasn't having such a brain fart I'd write something clever.

      Thanx

      peppiv

[reply]
Re: Increment Number with form button push
by SarahM (Monk) on Jun 13, 2002 at 19:43 UTC
    I'm not sure what you are trying to do... you declare $limit twice. And you never use $add_limit, which looks like the variable you would want. Is there more code, or am I just missing something?
[reply]
      Update

      My mistake! I meant:

      print qq($add_limit);

      peppiv
[reply]
[d/l]
        Then you need to change $limit in the form to $add_limit as well!
[reply]

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