Form with varying no. of fields - how to determine which fields were posted?

[bunner_bob]

I have a script generating a form with a varying number of checkbox fields. This is for an item/category setup, and the number of categories (and their ids) varies depending on various factors.

So the form might have:

<input type="checkbox" name="category12" value="checked" />Category 12<br />
<input type="checkbox" name="category13" value="checked" />Category 13<br />
<input type="checkbox" name="category26" value="checked" />Category 26<br />

and so on - basically any number of checkboxes.

At the moment I'm doing the following clunk:

for ($i=1; $i<=99; $i++) {
    if ($_POST['category' . $i]) {
        $categorylist[] = $i ;
    }
}

which is a ridiculously brute-force way of doing it. What I want to do is say "for every element in the $_POST array whose key starts with "category" followed by a number, do something with the number".

Any ideas?

• Bob

[devinemke]

pass the checkboxes as an array:

<input type="checkbox" name="category[]" value="12" />Category 12<br /> 
<input type="checkbox" name="category[]" value="13" />Category 13<br /> 
<input type="checkbox" name="category[]" value="26" />Category 26<br />

then you will have an array called $_POST['category'] with all of the checked boxes.