Re: Object Undefinded index

In my view, to keep the object oriented approach cleaner you should use another class for describing your item, like: class Item { var $_product_id; var $_quantity; function Item($productId, $quantity) {

    $this->_product_id = $productId;
    $this->_quantity = $quantity;

} function getProductID() {

    return $this->_product_id;

} function getQuantity() {

    return $this->_quantity;

} } Then your Cart class should be defined as follows: class Cart { var $_items; function Cart() {

    $this->_items = array();

} function addItem($item) {

    $this->_items[] = $item;

} function getItem($id) {

    return $this->_items[$id];

} } To add a new item to the cart first create the new item by calling the items constructor and then call addItem method of the Cart class(object): $MyCart = new Cart(); ... $newItem = new Item("10", 1); $MyCart->addItem($newItem); To iterate items in a Cart you may do something like that: foreach ($MyCart->getItems as $Item) { echo($Item->getProductId(), $Item->getQuantity); } Allex Steve Turner wrote:

I am just learning to use objects. I am messing around with a shopping cart object, but am having confusing problems. I am getting an undefined index error when trying to assign a key value pair to an array variable within an object. I am confused becuase I believe this is how you assign array variables outside an object. It acts like the variable is undefined. Thanks for the help. Steve Turner //-------------------------------------------------- class Cart {

    var $items;  // Items in shopping cart

    // Add $quantity articles of $product_id to the cart

    function add_item ($product_id, $quantity = 1)
    {
        $this->items[$product_id] += $quantity;
    }

    // Take $quantity articles of $product_id out of the cart

    function remove_item ($product_id, $quantity)
    {
        if ($this->items[$product_id] > $quantity)

{

            $this->items[$product_id] -= $quantity;
            return true;
        }

else {

            return false;
        }
    }

} //I am interacting with the object with the following code $cart = new Cart; $cart->add_item("10", 1); foreach ($cart as $product_id => $quantity) { echo $product_id . "<br>" . $quantity; }