question about an declaring array

Hello group,

I'm trying to implement a shopping cart and currently have a problem
as following. First, I will explain. Consider a page as "products.php"

This page has a list of products such as:

product name price button (for each
row)

A 8.00
Add_to_Cart button
B 8.00
Add_to_Cart button
C 12.00
Add_to_Cart button

In this page (product.php) : I have wrapped up the "Add to car" button
in a form where it takes the product id and category id of the product
to a "add2cart.php" using POST method.


<form action="addtocart.php" method="post">
<input type="hidden" name="productid" value="<?php echo
htmlentities($productid); ?>" />
<input type="hidden" name="categoryid" value="<?php echo
htmlentities($selected_category); ?>" />
<input type="submit" value="Add to Cart" />
</form>

In add2car.php I have:

<?php
session_start();

$_SESSION['order'][]= array("order" => array(
'categoryid' => $_POST['categoryid'],
'productid' => $_POST['productid'],
'quantity' => ???? )
);



Ok, the problem is that I don't know how to keep adding added product
into the SESSION array or don't know how to append it to pre-existing
data in $SESSION[]. Currently, If I add the 2nd item the previous
item is replaced.

Sometimes user adds product A and then he/she adds it later on and I
need to keep track of quantity of a specific added item in cart.

1) is the array declared properly base on what I need? how to append
to the array?
2) how to increment the quantify of select product if already exists
in the array?

Thanks.

I think I'd have a quantity field and then do

$_SESSION['order'][]= array(
'categoryid' => $_POST['categoryid'],
'productid' => $_POST['productid'],
'quantity' => $_POST['quantity'] );


--
Geoff Berrow 0110001001101100010000000110
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http://slipperyhill.co.uk