variable looping

Anon

I have a form that has variables val1 through val20. I need to get a total based on adding up the variable values.

Originally I had a simple statement:

$svar = val1 + val2 + val3...+ val20;

For a cleaner solution I switched to:

$svar = 0;
for($n=1; $n<=20; $n++) {
$svar += ${"val". $n};
}

Now, what I would like to do is to be able to port this section to other pieces of code, so the number of form fields can be changed without having to touch the script. Something like this:

$svar = 0;
$n = 1;
while (isset(${"val". $n}) {
$svar += ${"val". $n++};
}

Unfortunately this gives me parse errors on the while line, and I am not sure why. Is this heading in the right direction, and what do I need to do to get rid of the parse errors?

Also -- someone suggested that an array might be more efficient, but I am not sure why, would you consider using an array for this process?

Thanks!

techek

You could use variable variables (as you're trying to right now) or you could use arrays. Take a look at www.php.net/array to get more info on it.

That way you could do this which might look and be much more efficient and cleaner to use than variable variables :

<?php

$val = array(
'none' => '23',
'techek' => '27',
'allan' => '25',
);

while(list($index, $value) = each($val)) {
$total += $value;
}

echo "total = $total<br>\n";

Try it out and give me all call if you want more help!

Anon

I don't know if the concept is valid, but you are missing a close-parenthesis:

$svar = 0;
$n = 1;
while (isset(${"val". $n})) {
$svar += ${"val". $n++};
}

[deleted]

"Is this heading in the right direction, and what do I need to do to get rid of the parse errors?"

No. The while loop will stop on the first var it finds that is not set. So if your sequence of vars is interrupted, you will only get the first 'half' of the results.

Arrays are built especially to contain sequences of numbers/values, and they can be processed much much much more efficiently than variables. For one thing, you can send an array to a function, which you can't do with an unknown number of variables.

Anon

Techek,

I think I got it using arrays:

reset ($HTTP_POST_VARS);
while(list ($index, $value) = each($HTTP_POST_VARS)) {
$svar += $value;
}

This seems to work great, and it handles the problem, with the other method, of choking on skipped form fields.

Thanks again for the help.

Anon

btw: If you want to see what you were hepling to create:

http://www.allan.org/castaway/

Anon

I would just name each input field:
var[]

then do:

foreach($var as $loop){
$total = $loop + $total;
}

[deleted]

Whoah there, that is NOT a good solution.

It may work, but this just adds all the variables from the form. If you have a some hidden fields, or a numeric value in another field, your result will be screwed up.

Instead, give all your HTML form fields that contain the values that you want to add the same name: val[]

Then after submitting, there will be an array inside the POST_VARS array, and you can do this trick on that array, then it will work and be safe.

Anon

Which explains why it worked for me...there are no other fields in this form 🙂, just the values I am trying to add.

Thanks for the additional information, and I will post the new code once I get it worked out.