Can someone explain this to me?

[abc456]

In class we have a prompt to write a code for a bank account. http://www.cs.indiana.edu/classes/a290-gamebryo/examples/ch09.pdf <- this link goes through it in steps but i don't understand where things go. Like where do I put the constructors, member functions, etc. If you could explain it to me better than they do I'd appreciate it. Keep in mind that I only started to learn programming a few months ago. Thanks in advance!

[TarikNeaj]

You've been programming for a few months but dont even know where to put functions?

class BankAccount
{
public:
 BankAccount();
 BankAccount(double initial_balance);
 void deposit(double amount);
 void withdraw(double amount);
 void add_interest(double rate);
 double get_balance() const;
private:
 ...
};

That code is in the example. This is called a class. [code]BankAccount();

is the constructor. the voids are member functions. etc.
[/code]

If you want to learn how classes works. Try googling it, or watch some tutorials on youtube. always helps.

[tipaye]

You have several choices, but I'll only mention the 2 most appropriate here. I've organised the code into 3 blocks below and you could have:
1. each block in it's own file, one header and 2 implementation files
2. all 3 blocks in one implementation file.

See the comments I've added to the code:

// This is the class declaration. It could be in it's own file, e.g. BankAccount.h
// use header guards if it's in a separate file, like so:

// #ifndef BANK_ACCOUNT_H
// #define BANK_ACCOUNT_H

/**
 A bank account whose balance can be changed by deposits and withdrawals.
*/
class BankAccount
{
public:
	/**
	Constructs a bank account with zero balance.
	*/
	BankAccount();
	/**
	Constructs a bank account with a given balance.
	@param initial_balance the initial balance
	*/
	BankAccount(double initial_balance);
	/**
	Makes a deposit into this account.
	@param amount the amount of the deposit
	*/
	void deposit(double amount);
	/**
	Makes a withdrawal from this account, or charges a penalty if
	sufficient funds are not available.
	@param amount the amount of the withdrawal
	*/
	void withdraw(double amount);
	/**
	Adds interest to this account.
	@param rate the interest rate in percent
	*/
	void add_interest(double rate);
	/**
	Gets the current balance of this bank account.
	@return the current balance
	*/
	double get_balance() const;
private:
	double balance;
};

// use header guards if in a separate file, like so:
// #endif //BANK_ACCOUNT_H



*******************************************************************


// This is the implementation of the class declared above
// If the class is declared in a separate file, e.g. BankAccount.h,
// then this should also be in its own file, e.g. BankAccount.cpp
// it then follows that the header file must be included here like so:

// #include "BankAccount.h"

double BankAccount::get_balance() const
{
	return balance;
}

void BankAccount::deposit(double amount)
{
	balance = balance + amount;
}

void BankAccount::withdraw(double amount)
{
	const double PENALTY = 10;
	if (amount > balance)
	{
		balance = balance - PENALTY;
	}
	else
	{
		balance = balance - amount;
	}
}

void BankAccount::add_interest(double rate)
{
	double amount = balance * rate / 100;
	deposit(amount);
}

BankAccount::BankAccount()
{
	balance = 0;
}

BankAccount::BankAccount(double initial_balance)
{
	balance = initial_balance;
}  



*******************************************************************


// This is the test program, again this could be in a separate file, 
// or all 3 could be in one .cpp file. notice the standard library 
// headers included, for cout, endl, fixed and setprecision
// If it's in a file by itself, the BankAccount class must be declared, 
// by including the header like so:

// #include "BankAccount.h"

#include <iostream>
#include <iomanip>

int main()
{
	BankAccount harrys_account(1000);
	harrys_account.deposit(500); // Balance is now $1500
	harrys_account.withdraw(2000); // Balance is now $1490
	harrys_account.add_interest(1); // Balance is now $1490 + 14.90
	std::cout << std::fixed << std::setprecision(2)
	<< harrys_account.get_balance() << std::endl;
	return 0;
}

[abc456]

tipaye: thanks for helping me out with that. it keeps saying balance is undefined and undeclared. do you know how to fix that?

[LB]

Make sure line 44 exists and that you're implementing your member functions instead of creating identically-named global functions.

[tipaye]

If you're still having problems, post your whole code. I also think LB's guess is the likely, problem. Otherwise, happy coding.