having trouble with my ringupsale, showlast, and cancel function - c++

Question

This program uses inheritance and dynamic arrays
enum ItemType {BOOK, DVD, SOFTWARE, CREDIT};
class Sale
{
public:
Sale();
void MakeSale(ItemType x, double amt);
ItemType Item();
double Price();
double Tax();
double Total();
void Display();
private:
double price;
double tax;
double total;
ItemType item;
}
//****************************SALE.CPP*******************************
#include<iostream>
#include<cmath>
#include "sales.h"
using namespace std;
Sale::Sale()
{
price = 0;
tax = 0;
total = 0;
}
// Credit are suppose to have no tax all other purchases have
void Sale::MakeSale(ItemType x, double amt)
{
item = x;
if(item == CREDIT)
total = amt;
else
total = (amt * tax);
}
ItemType Sale::Item()
{
return item;
}
double Sale::Price()
{
return price;
}
double Sale::Tax()
{
return tax;
}
double Sale::Total()
{
return total;
}
// display function
void Sale::Display()
{
if(item = BOOK)
cout<<"BOOK"<<" "<<'$'<<price<<" ";
cout<<"Tax"<<" "<<'$'<<tax<<" "<<"Total:";
cout<<" "<<'$'<<total<<endl;
if(item = DVD)
cout<<"DVD"<<" "<<'$'<<price<<" ";
cout<<"Tax"<<" "<<'$'<<tax<<" "<<"Total:";
cout<<" "<<'$'<<total<<endl;
if(item = SOFTWARE)
cout<<"SOFTWARE"<<" "<<'$'<<price<<" ";
cout<<"Tax"<<" "<<'$'<<tax<<" "<<"Total:";
cout<<" "<<'$'<<total<<endl;
if(item = CREDIT)
cout<<"CREDIT" <<" "<<'$'<<price<<" ";
cout<<"Tax"<<" "<<'$'<<tax<<" "<<"Total:";
cout<<" "<<'$'<<total<<endl;
}
//****************************Register.h*******************************
#include<iostream>
#include "sales.h"
using namespace std;
const int BLOCKSIZE = 5;
class Register : Sales
{
public:
Register(int id, double start_amount);
~Register();
int GetID();
double GetAmount();
void RingUpSale(enum ItemType Saletype, double amount);
void ShowLast();
void ShowAll();
void Cancel();
double SalesTax(int n);
private:
int Register_ID;
int Current_ArraySize;
int Number_of_Records;
double Register_Amount
Sale *Sales_Array;
Sale *Temp_Array;
void expandlist();
void shrinklist();
}
//******************************Register.cpp*********************************
#include<iostream>
#include "register.h"
using namespace std;
// *******************************************************************
// * Initializing these values for a starting value
// *******************************************************************
int Current_ArraySize = 0;
int Number_of_Records = 0;
// ******************************************************************
// *
// * Function: Constructor for Register
// * Parameters: ID number and starting amount
// *
// * Description: Initializes the ID number and the register amount
// *
// ******************************************************************
Register::Register(int id, double amount)
{
int * Sales_Array;
Sales_Array = new int[BLOCKSIZE];
int Register_ID = id;
double Register_amount = amount;
}
// ******************************************************************
// *
// * Function: Destructor for Register
// * Parameters:
// *
// * Description: Deletes Sales Array
// *
// ******************************************************************
Register::~Register()
{
delete[] Sales_Array;
}
// ******************************************************************
// *
// * Function: GetID
// * Parameters:
// *
// * Description: returns ID
// *
// ******************************************************************
int Register::GetID()
{
return Register_ID;
}
// ******************************************************************
// *
// * Function: GetAmount
// * Parameters:
// *
// * Description: returns amount
// *
// ******************************************************************
double Register::GetAmount()
{
return Register_Amount;
}
// ******************************************************************
// *
// * Function: RingUpSale
// * Parameters: enum ItemType amd amount
// *
// * Description: Takes in items sold and amount then adds them
// * to the previous list.
// *
// ******************************************************************
Not sure why ringupsale is not working!
void Register::RingUpSale(enum ItemType Saletype, double amount)
{
Current_ArraySize++;
newSale_Array = new Sales_Array[Current_ArraySize];
//copy all the old sale items into the new list.
for (int i=0; i<Current_ArraySize; i++)
{
newSale_Array[i] = Sales_Array[i];
}
//add the new sale at the end of the new array
newSale_Array[Current_ArraySize-1] = newSale;
//set the sale array as the new array
Sales_Array = newSale_Array;
Number_of_Records++;
}
// ******************************************************************
// *
// * Function: ShowAll
// * Parameters:
// *
// * Description: Lists the contents of the register
// *
// ******************************************************************
I am trying to show all the contents of the sales array
void Register::ShowAll()
{
int i;
cout << "the elements int the array are:" <<endl;
// for(i=0; i<Current_ArraySize; i++)
// cout << Sales_Array(Sales_Array+i) << endl;
}
// ******************************************************************
// *
// * Function: ShowLast
// * Parameters:
// *
// * Description: Show the last transaction made
// *
// ******************************************************************
I am just trying to show the last content of the sales array
void Register::ShowLast()
{
cout << "The last sale was:" << endl;
// cout << Sale[Current_ArraySize - 1] << endl;
}
// ******************************************************************
// *
// * Function: Salestax
// * Parameters:
// *
// * Description: returns the amount of salestax
// *
// ******************************************************************
double Register::SalesTax(int n)
{
double RunTotal=0;
if (n<0)
{
cout<<"Invalid entry.";
return 0;
}
else if (n>Number_of_Records)
{
for(int i=0; i<=Number_of_Records; i++)
{
RunTotal=RunTotal+Sales_Array[i].Tax();
return RunTotal;
}
}
else
{
for(int i=0; i<=n; i++)
{
RunTotal=RunTotal+Sales_Array[i].Tax();
return RunTotal;
}
}
}

Answer 1

This is a problem:
Register::Register(int id, double amount)
{
int * Sales_Array;
Sales_Array = new int[BLOCKSIZE];
int Register_ID = id;
double Register_amount = amount;
}
as the local variable Sales_Array in the constructor of Register hides the member variable Register::Sales_Array, meaning Register::Sales_Array is an unintialised pointer. Register::Sales_Array is then used, causing undefined behaviour and will be the reason that Register::RingUpSale() is not working. Remove the declarations in the constructor and use an initializer list instead:
Register::Register(int id, double amount) :
Current_ArraySize(0),
Number_of_Records(0),
Sales_Array(0),
Register_ID(id),
Register_Amount(amount)
{}
Note that these lines introduced two new variables, unrelated to the class:
int Current_ArraySize = 0;
int Number_of_Records = 0;
Have also added these to the initializer list above.
Finally, you are violating the Rule of Three as you have dynamically allocated members but have not defined a copy constructor and assignment operator, or at least declared them private to make Register uncopyable.
As this is C++, use a std::vector<Sale> instead of explicitly managing dynamic memory.