Recap - Bank Account Manager

Part of the Object Oriented Programming section of Coddy's C++ journey — lesson 33 of 104.

Challenge

Easy

Let's build a complete Bank Account Manager that brings together all the class property concepts you've learned in this chapter: private members with getters and setters, const member functions, mutable members, static variables and methods, and friend functions.

You'll create two files to organize your code:

BankAccount.h: Define a BankAccount class that manages account data with proper encapsulation. Your class should have:
- Private members: accountNumber (string), ownerName (string), balance (double), and a mutable int queryCount to track how many times the balance has been checked
- A private static member totalAccounts to track how many accounts exist
- A constructor that takes the account number, owner name, and initial balance. It should initialize queryCount to 0 and increment totalAccounts
- Const getters: getAccountNumber(), getOwnerName(), and getBalance() — the balance getter should increment queryCount each time it's called
- A const getter getQueryCount() that returns how many times the balance was checked
- A deposit(double amount) method that adds to the balance only if the amount is positive
- A withdraw(double amount) method that subtracts from the balance only if the amount is positive and doesn't exceed the current balance
- A static method getTotalAccounts() that returns the total number of accounts created
- Declare a friend function transfer(BankAccount& from, BankAccount& to, double amount) that moves money between accounts — it should only transfer if the amount is positive and the source has sufficient funds
Define the static member and the friend function after the class definition.
main.cpp: Demonstrate all these features working together. Read two owner names and two initial balances from input (four lines total: name1, balance1, name2, balance2), then:
- Create two BankAccount objects with account numbers "ACC001" and "ACC002"
- Print "Total accounts: <count>"
- Print "<name>: "<name>: $<balance>"lt;balance>" for the first account
- Print "<name>: "<name>: $<balance>"lt;balance>" for the second account
- Deposit 500.0 into the first account
- Print "After deposit - <name>: "After deposit - <name>: $<balance>"lt;balance>" for the first account
- Transfer 300.0 from the first account to the second using the friend function
- Print "After transfer:"
- Print " <name>: " <name>: $<balance>"lt;balance>" for the first account
- Print " <name>: " <name>: $<balance>"lt;balance>" for the second account
- Print "Query count for <name>: <count>" for the first account

Format all balance values with two decimal places using std::fixed and std::setprecision(2) from <iomanip>. Convert balance inputs from strings to doubles using std::stod().

Don't forget header guards in your header file and to include <string> and <iostream> where needed.

Try it yourself

#include <iostream>
#include <string>
#include <iomanip>
#include "BankAccount.h"

int main() {
    // Read input
    std::string name1, name2;
    std::string balance1Str, balance2Str;
    
    std::getline(std::cin, name1);
    std::getline(std::cin, balance1Str);
    std::getline(std::cin, name2);
    std::getline(std::cin, balance2Str);
    
    double balance1 = std::stod(balance1Str);
    double balance2 = std::stod(balance2Str);
    
    // Set output formatting for 2 decimal places
    std::cout << std::fixed << std::setprecision(2);
    
    // TODO: Create two BankAccount objects with account numbers "ACC001" and "ACC002"
    
    // TODO: Print "Total accounts: <count>"
    
    // TODO: Print "<name>: $<balance>" for the first account
    
    // TODO: Print "<name>: $<balance>" for the second account
    
    // TODO: Deposit 500.0 into the first account
    
    // TODO: Print "After deposit - <name>: $<balance>" for the first account
    
    // TODO: Transfer 300.0 from the first account to the second using the friend function
    
    // TODO: Print "After transfer:"
    
    // TODO: Print "  <name>: $<balance>" for the first account (note the 2-space indent)
    
    // TODO: Print "  <name>: $<balance>" for the second account (note the 2-space indent)
    
    // TODO: Print "Query count for <name>: <count>" for the first account
    
    return 0;
}

All lessons in Object Oriented Programming

1Fundamentals of OOP

External Files C++ Build & Compilation Header Files & Source Files Namespaces & Scope Introduction to OOP in C++Classes vs Objects The 'this' Pointer Methods (Member Functions)Attributes (Data Members)Ctors & Dtors Basics Recap - Simple Calculator

4Class Properties

Instance vs Static Members Getters and Setters Const Member Functions Mutable Keyword Static Methods and Variables Friend Functions & ClassesRecap - Bank Account Manager

7Inheritance

Basic Inheritance Inheritance Access Levels Ctor & Dtor Call Order Method Overriding Virtual Functions & VTable Multiple Inheritance Virtual Inheritance Recap - Employee Hierarchy

10STL Overview

STL Overview & Philosophy STL Containers Iterators STL Algorithms Functors & Lambda Expressions Recap - Word Frequency

13Design Patterns Part 1

Intro to Design Patterns Singleton Pattern Factory & Abstract Factory Builder Pattern Observer Pattern Strategy Pattern