Advanced Object-Oriented Programming Concepts

Introduction

In this exercise, we’ll delve into advanced OOP concepts by designing a complex system. Our system will involve abstract classes, interfaces, and multiple interacting classes to demonstrate the power and flexibility of these concepts.

System Design: Online Banking System

Let’s design an Online Banking System that includes various entities such as accounts, transactions, and user authentication.

Advanced OOP Concepts Utilized:

1. Abstract Classes: Represented by an Account abstract class, providing a common interface for different types of accounts.

2. Interfaces: Used to define contracts for behaviors. An Authentication interface is created for user authentication.

3. Inheritance and Polymorphism: Demonstrated through various account types (e.g., SavingsAccount, CheckingAccount) inheriting from the Account class.

4. Composition: Different components (e.g., Transaction class) are composed within the system to encapsulate related functionalities. ### C++ Code Implementation:

#include
#include

// Abstract class representing an account
class Account {
public:
    virtual void deposit(double amount) = 0;
    virtual void withdraw(double amount) = 0;
    virtual void display

Balance() const = 0;
    virtual ~Account() {}
};

// Interface for user authentication
class Authentication {
public:
    virtual bool authenticate

User(const std::string& username, const std::string& password) const = 0;
    virtual ~Authentication() {}
};

// Concrete class representing a savings account
class Savings

Account : public Account {
private:
    double balance;

public:
    Savings

Account() : balance(0) {}

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

    void withdraw(double amount) override {
        if (amount <= balance) {
            balance -= amount;
        } else {
        std::cout << "Insufficient funds\n";
        }
    }

    void display

Balance() const override {
        std::cout << "Savings Account Balance: $" << balance << "\n";
    }
};

// Concrete class representing a checking account
class Checking

Account : public Account {
private:
    double balance;

public:
    Checking

Account() : balance(0) {}

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

    void withdraw(double amount) override {
        if (amount <= balance) {
            balance -= amount;
        } else {
        std::cout << "Insufficient funds\n";
        }
    }

    void display

Balance() const override {
        std::cout << "Checking Account Balance: $" << balance << "\n";
    }
};

// Transaction class representing a banking transaction
class Transaction {
public:
    void execute(Account& account, double amount) {
        account.withdraw(amount);
    }
};

// User class implementing authentication
class User : public Authentication {
public:
    bool authenticate

User(const std::string& username, const std::string& password) const override {
        // Simplified authentication logic for demonstration
        return username == "user" && password == "password";
    }
};

int main() {
    // Sample usage of the Online Banking System
    Savings

Account savings

Account;
    Checking

Account checking

Account;
    Transaction transaction;
    User user;

    // Authentication
    if (user.authenticate

User("user", "password")) {
        // Transactions
        savings

Account.deposit(1000);
        savings

Account.display

Balance();

        transaction.execute(savings

Account, 200);
        savings

Account.display

Balance();

        checking

Account.deposit(500);
        checking

Account.display

Balance();
    } else {
        std::cout << "Authentication failed\n";
        }

    return 0;
}

### Explanation: - `Account` is an abstract class representing the common interface for different account types (`Savings

Account`, `Checking

Account`).- `Authentication` is an interface for user authentication implemented by the `User` class.- `Transaction` is a class representing a banking transaction, showcasing composition within the system.- The `main` function demonstrates sample usage of the Online Banking System, including authentication, deposits, withdrawals, and displaying account balances.

## Conclusion

Feel free to expand upon this design, add more features, or modify the code to explore additional aspects of advanced OOP concepts. By mastering advanced OOP concepts, you've gained the ability to create modular, scalable, and maintainable designs. As you continue your architectural endeavors, apply these principles to craft software systems that stand the test of complexity and change. Happy designing!