Here is the design outut for one of the classes: Invoice.h

(What data members are needed?)

class Invoice
{
public:
  /**
   * Initialize an Invoice for up to maxItems LineItems
   */
  Invoice();
  Invoice(int maxItems);
  Invoice(const Address& addr, int maxItems);

  /**
   * Formats the invoice
   */
  string format();

  /**
   * Adds a line item for a product and quantity to
   * this invoice.
   */
  void add(const Product& p, int quantity);

};