Notice: Undefined Index & Undefined Offset

[Accolade]

I am attempting to add a product to my cart using an increment. It works, however, when I add the first of any product, it gives me the following errors:

 

Notice: Undefined index: cart in C:\wamp\www\cart.php on line 36

Notice: Undefined offset: 41 in C:\wamp\www\cart.php on line 36

 

Once the quantity increases above 1, there are no errors. Unsure what is going on.

 

switch($action) {

case "add":
$_SESSION['cart'][$product_id]++;
break;

case "remove":
if (isset($_SESSION['cart'][$product_id])) {
$_SESSION['cart'][$product_id]--;}
if($_SESSION['cart'][$product_id] == 0) unset($_SESSION['cart'][$product_id]);
break;
}

 

Line 36 is:

 

$_SESSION['cart'][$product_id]++;

Edited November 5, 2012 by Accolade

[Accolade]

Dont fret, I worked it out!

[Scott_S]

tag this as "solved" please