1protected string GetCartString()
2    {
3        HttpCookieCollection hc = new HttpCookieCollection();
4        hc = Request.Cookies;
5        string ItemsQuantity = "";
6        foreach (String sc in hc)
7        {
8            HttpCookie c = hc[sc];
9            ItemsQuantity += c.Value.ToString().Trim() + ",";
10        }
11
12        //trim end comma
13        if (ItemsQuantity.Length > 0)
14            ItemsQuantity = ItemsQuantity.Substring(0, ItemsQuantity.Length - 1);
15
16        return ItemsQuantity;
17    }

The string is in the following format:  "ProductID:Quantity,ProductID:Quantity"