php session update product if id already in the session - php

Question

The following function is on carts page, after a user has added product from previous product page. The problem is I need the multidimensional array just to update quantity in cart for same product code being added.
Can someone help me add an if statement so when the same productcode is added quantity increases?
Like this answer however my add to cart is different. PHP Sessions shopping cart: update product if it's already id the session
function AddToCart()
{
$cart = isset($_SESSION['cart']) ? $_SESSION['cart'] : '';
$itemcount = isset($_SESSION
['itemcount']) ? $_SESSION['itemcount'] : 0;
{
$i = array_search($_POST['productcode'], $cart[PRODUCTCODE]);
$cart[PRODUCTCODE] [$itemcount] = $_POST['productcode'];
$cart[PRODUCTNAME] [$itemcount] = $_POST['productname'];
$cart[QUANTITY][$itemcount] = intval($_POST['quantity']);
$cart[PRICE][$itemcount] = $_POST['price'];
$itemcount = $itemcount + 1;
if(strlen($error) == 0) {
$_SESSION['cart'] = $cart;
$_SESSION['itemcount'] = $itemcount;
}
return $error;
}

Answer 1

Try this.
//check for an existing match
$found = FALSE;
if($cart){
$idx = 0;
foreach($cart[PRODUCTCODE] as $idx => $product){
if($product == $_POST['productcode']){
$found = TRUE;
break;
}
}
}
//if we found a match
if($found){
$cart[QUANTITY][$idx] += intval($_POST['quantity']);
}
//otherwise add new item
else{
//your other code here
}