using System;

​

// BankAccount class

public class BankAccount

{

    // 1. Properties

    protected string AccountID { get; set; }

    public string OwnerName { get; set; }

    public double Balance { get; set; }

    private int OpeningYear { get; set; }

    // Default constructor

    public BankAccount() { }

    // 2. Second constructor with 4 parameters

    public BankAccount(string accountID, string ownerName, double balance, int openingYear)

    {

        AccountID = accountID;

        OwnerName = ownerName;

        Balance = balance;

        OpeningYear = openingYear;

    }

    // 3. PrintOwnerName function

    public void PrintOwnerName()

    {

        Console.WriteLine("Owner Name: " + OwnerName);

    }

    // 4. ShowBalance function

    public virtual void ShowBalance()

    {

        Console.WriteLine("Balance: " + Balance);

    }

}

​

// CheckingAccount class

public class CheckingAccount : BankAccount

{

    // Properties

    public int WithdrawLimit { get; set; }

    // Default constructor

    public CheckingAccount() { }

    // 5. Second constructor with 5 parameters

    public CheckingAccount(string accountID, string ownerName, double balance, int openingYear, int withdrawLimit)

        : base(accountID, ownerName, balance, openingYear)

    {

        WithdrawLimit = withdrawLimit;

    }

    // 6. PrintOwnerName function (Method Hiding)

    public new void PrintOwnerName()

    {

        Console.WriteLine("CheckingAccount OwnerName: " + OwnerName);

    }

    // 7. ShowBalance function (Method Overriding)

    public override void ShowBalance()

    {

        Console.WriteLine("CheckingAccount Balance: " + Balance);

    }

    public void Function()

    {   

        // 8. Question

        // Can you print out AccountID? Why or why not?

        // Console.WriteLine(AccountID);

        // [Answer] No, because AccountID is protected, and can only be accessed within the class itself and derived classes.

​

        // Can you print out OpeningYear? Why or why not?

        // Console.WriteLine(OpeningYear);

        // [Answer] No, because OpeningYear is private and only accessible within the BankAccount class itself.

    }

}

​

public class Program

{

    public static void Main()

    {

        // 9. Uncommented to test functionality

        CheckingAccount ca = new CheckingAccount("A12345", "Mary", 5000, 12, 6);

        ca.PrintOwnerName(); 

        // What is this technique? (a) method hiding, (b) method overriding

        // [Answer] This is method hiding. ca.PrintOwnerName() calls the "new" method on the derived class.

        BankAccount ba = new CheckingAccount("B6789", "John", 3000, 22, 6);

        // This is called "polymorphism", where an instance of a derived class is used as an instance of the base class.

        ba.PrintOwnerName(); // This calls the method of the base class.

        ba.ShowBalance();    // This calls the overridden method on the derived class.

        // What is this technique? (a) method hiding, (b) method overriding

        // [Answer] This is method overriding, as ShowBalance() was overridden in the derived class.

    }

}

​