Question

I am doing a homework assignment for my summer OO class and we need to write two classes. One is called Sale and the other is called Register. I’ve written my Sale class; here’s the .h file:

enum ItemType {BOOK, DVD, SOFTWARE, CREDIT};

class Sale
{
public:
    Sale();         // default constructor, 
            // sets numerical member data to 0

    void MakeSale(ItemType x, double amt);  

    ItemType Item();        // Returns the type of item in the sale
    double Price();     // Returns the price of the sale
    double Tax();       // Returns the amount of tax on the sale
    double Total();     // Returns the total price of the sale
    void Display();     // outputs sale info 

private:
    double price;   // price of item or amount of credit
    double tax;     // amount of sales tax 
    double total;   // final price once tax is added in.
    ItemType item;  // transaction type
};

For the Register class we need to include a dynamic array of Sale objects in our member data. We cannot use the vector class. How is this done?

Here’s my ‘Register’ ‘.h’

class Register{
public:

Register(int ident, int amount);
~Register();
int GetID(){return identification;}
int GetAmount(){return amountMoney;}
void RingUpSale(ItemType item, int basePrice);
void ShowLast();
void ShowAll();
void Cancel();
int SalesTax(int n);

private:

int identification;
int amountMoney;

};

Answer 1

All you need in the Register class is an array of Sale objects, and a item counter to remember how many sales were made.

For example if there are 10 items in the register you will need to do this:

int saleCount = 10;
Sale[] saleList = new Sale[saleCount];

To make the array dynamic you will need to create a new Sale array every time the sale count is incremented, and copy all the items in saleList into a new sale list. Finally add the new Sale at the end.

saleCount++;
Sale[] newSaleList = new Sale[saleCount];
//copy all the old sale items into the new list.
for (int i=0; i<saleList.length; i++){
  newSaleList[i] = saleList[i];
}
//add the new sale at the end of the new array
newSaleList[saleCount-1] = newSale;
//set the saleList array as the new array
saleList = newSaleList;