System.Xml.XmlDocument.Save C# (CSharp) Method

        public virtual void Save(Stream outStream)
        {
            XmlDOMTextWriter xw = new XmlDOMTextWriter(outStream, TextEncoding);
            if (_preserveWhitespace == false)
                xw.Formatting = Formatting.Indented;
            WriteTo(xw);
            xw.Flush();
        }

        public void updateCartFile(List<CartObject> newCartObj)
        {
            bool found = false;

            string cartFile = "C:\\Users\\Kiran\\Desktop\\cart.xml";

            if (!File.Exists(cartFile))
            {
                XmlTextWriter xWriter = new XmlTextWriter(cartFile, Encoding.UTF8);
                xWriter.Formatting = Formatting.Indented;
                xWriter.WriteStartElement("carts");
                xWriter.WriteStartElement("cart");
                xWriter.WriteAttributeString("emailId", Session["emailId"].ToString());
                xWriter.Close();
            }

            XmlDocument doc = new XmlDocument();
            doc.Load(cartFile);
            foreach (CartObject cartItem in newCartObj)
            {
                foreach (XmlNode xNode in doc.SelectNodes("carts"))
                {
                    XmlNode cartNode = xNode.SelectSingleNode("cart");
                    if (cartNode.Attributes["emailId"].InnerText == Session["emailId"].ToString())
                    {
                        found = true;
                        XmlNode bookNode = doc.CreateElement("book");
                        XmlNode nameNode = doc.CreateElement("name");
                        nameNode.InnerText = cartItem.itemName;
                        XmlNode priceNode = doc.CreateElement("price");
                        priceNode.InnerText = cartItem.itemPrice.ToString();
                        XmlNode quantityNode = doc.CreateElement("quantity");
                        quantityNode.InnerText = "1";
                        bookNode.AppendChild(nameNode);
                        bookNode.AppendChild(priceNode);
                        bookNode.AppendChild(quantityNode);
                        cartNode.AppendChild(bookNode);
                    }
                }
                if(!found)
                  {
                        XmlNode cartNode = doc.CreateElement("cart");
                        cartNode.Attributes["emailId"].InnerText = Session["emailId"].ToString();
                        XmlNode bookNode = doc.CreateElement("book");
                        XmlNode nameNode = doc.CreateElement("name");
                        nameNode.InnerText = cartItem.itemName;
                        XmlNode priceNode = doc.CreateElement("price");
                        priceNode.InnerText = cartItem.itemPrice.ToString();
                        XmlNode quantityNode = doc.CreateElement("quantity");
                        quantityNode.InnerText = "1";
                        bookNode.AppendChild(nameNode);
                        bookNode.AppendChild(priceNode);
                        bookNode.AppendChild(quantityNode);
                        cartNode.AppendChild(bookNode);
                        doc.DocumentElement.AppendChild(cartNode);

                  }
                }
            doc.Save(cartFile);
        }