Help with C++ project

[prestonprice57]

Hey I have a project for school where I have to make a bank class program using classes. I have to make a base class named Account and then 3 derived classes, Checking, Savings, and Loan. The problem I have is this program is read from a file our teacher created, so in main I have a while loop going through the file and if it reads an s it makes a savings object, if it is l it makes a loan object, etc. This is working fine but this objects also take in an account number, so transactions can be processed later. Here is the code for main:

main()
{

   ifstream in;
   char transactionType;
   int accountNumber;
   string accountName;
   double initialBalance;
   double theInterestRate;
   double theCheckFee;
   double theTransactionAmount;
   string theAccountType;

   in.open("hello.txt");

   if (in.fail())
      cout << "Error reading file";

   Account account[5];

   while (!in.eof())
   {
      in >> transactionType;

      if (transactionType == 's')
      {
         in >> accountNumber;
         in >> accountName;
         in >> initialBalance;
         in >> theInterestRate;
         Savings savingAccount(accountNumber, accountName, initialBalance,
                               theInterestRate);
   cout << "new account..." << endl << accountName << " (savings)";
         cout << savingAccount;

         account[accountNumber] = savingAccount;
      }

      else if (transactionType == 'c')
      {
         in >> accountNumber;
         in >> accountName;
         in >> initialBalance;
         in >> theCheckFee;
         Checkings checkingAccount(accountNumber, accountName, initialBalance,
                                   theCheckFee);
         cout << "new account..." << endl << accountName << " (checking)";
         cout << checkingAccount;

         account[accountNumber] = checkingAccount;
      }

      else if (transactionType == 'l')
      {
         theAccountType = "loan";
         in >> accountNumber;
         in >> accountName;
         in >> initialBalance;
         in >> theInterestRate;
         initialBalance = -(initialBalance);
         Loan loanAccount(accountNumber, accountName, initialBalance,
                          theInterestRate, theAccountType);
         cout << "new account..." << endl << accountName << " (loan)";
         cout << loanAccount;

         account[accountNumber] = loanAccount;
      }
 else if (transactionType == 't')
      {
         in >> accountNumber;
         in >> theTransactionAmount;

         account[accountNumber].addTransaction(theTransactionAmount);

         cout << account[accountNumber];
      }

      else if (transactionType == 'u')
      {
         in >> accountNumber;

      }

      else
         cout << "Invalid Transaction Type";
   }

So I save the loan, savings, or checking objects back into an account array so I can sort through the accounts in the transaction part of the function. But then I am changing the Account object and the loan, checkings, or savings, aren't even taken in at all. And since transactions are different depending on if it is a loan, savings, or checking, it doesn't work. So how would I make this work? Virtual functions? Or is there a way to point to my loan, savings, or checking account with an account number without actually changing the values. Idk. I am confused so I'm sure I'm not making any sense.

[GCDEF]

You're experiencing what is called object slicing. Since your array is of type Account, it isn't capable of storing the different account types. You need to store an array, or better a vector or Account pointers, then create the sub account objects using new, instead of using local variables inside your if statements.

You'd have something like

Account* account[5];
account[accountNumber] = new Savings;

[prestonprice57]

Thanks that actually makes sense! Except when I set account[accountNumber] to new Savings how do I initialize Savings.

[Lindley]

Either give Savings a constructor taking the necessary arguments, or else you can initially hold it in a local Savings* and then assign that into the account array once you're done setting it up.

Don't forget that ever "new" must eventually have a corresponding "delete"!

[prestonprice57]

Alright I'll try giving that a shot!

[prestonprice57]

Alright so that whole deal worked. But I came across another problem. In my transaction if statement it says,

else if (transactionType == 't')
      {
         in >> accountNumber;
         in >> theTransactionAmount;

         account[accountNumber].addTransaction(theTransactionAmount);

         cout << account[accountNumber];
      }

And when I try to compile it I get an error that says "error: request for member âaddTransactionâ in âaccount[accountNumber]â, which is of non-class type âAccount*â"

Why is this? Oh and addTransaction is of type Account.

[Lindley]

With pointers, you use "->" rather than ".".

[prestonprice57]

Alright Awesome that worked! Now just one more problem (hopefully).
When I use cout in my transaction if statement, it outputs a bunch of hexadecimal numbers. Why does it do this? And I have the << operator overloaded and it works in my other if statements. It is

ostream& operator << (ostream &out, const Account &account1)
{
   cout.setf(ios::fixed);
   cout.precision(2);

   out << ": balance is $" << account1.initialBalance << endl << endl;

   return out;
}

[Lindley]

Well, for starters, you're calling setf and setprecision on cout, but actually operating on out---not necessarily the same stream. Fix that.

I don't know why the output would look like hex though, from what you've shown.

[prestonprice57]

Alright I have virtual functions that look like this:

double Account::addTransaction(double theTransactionAmount)
{
   initialBalance += theTransactionAmount;

   return initialBalance;
}

double Loan::addTransaction(double theTransactionAmount)
{
   initialBalance -= theTransactionAmount;

   return initialBalance;
}

double Checkings::addTransaction(double theTransactionAmount)
{
   initialBalance += theTransactionAmount;

   return initialBalance;
}

double Savings::addTransaction(double theTransactionAmount)
{
   initialBalance += theTransactionAmount;

   return initialBalance;
}

If that has anything to do with it. Thanks for helping by the way.

[prestonprice57]

It works when I output a normal object but when I output the pointer it gets messed up. Is there a reason for this? Do I need to set the pointer object to something?

[Paul McKenzie]

It works when I output a normal object but when I output the pointer it gets messed up.

Of course, because you're doing as you stated -- you're outputting a pointer. A pointer is just an integral value.

Do I need to set the pointer object to something?

Pointers must always point to something before you use them.

Dereference the pointer, and you get the object you want to output:

#include <iostream>

int main()
{
   int i = 10;
   int *pi = &i;  // pi is pointing to the i variable
   std::cout << *pi;
}

You see that 10 is printed.

Regards,

Paul McKenzie

[prestonprice57]

Alright so I think it's just that my overloaded extraction operator isn't working with the pointer object. Is there a way I can get it to work?

[prestonprice57]

Alright that makes sense. But how do I dereference a pointer to an object? Cause right now I have,

  account[accountNumber] = new Loan(accountNumber, accountName,
                                           initialBalance, theInterestRate);

[Lindley]

All pointers are dereferenced the same way.