Question

I have a method inside my derived class that I don’t have in my base class, is there any way to use the derived class method on an object with the base class type? I know that I can move the method to my base class but I don’t think I am supposed to do that..

Here is the code:

I want to use CalculateInterest() on my accounts in my loop, but the accounts are all of type Account, not SavingsAccount.

Method in SavingsAccount class:

 public decimal CalculateInterest()
        {
            return AcctBalance * interestRate;
        }

Loop in Main:

List<Account> accounts = new List<Account>();

            Account sAcct1 = new SavingsAccount(200, 0.10M);
            Account sAcct2 = new SavingsAccount(300, 0.12M);
            Account cAcct1 = new CheckingAccount(500, 2.00M);
            Account cAcct2 = new CheckingAccount(400, 1.50M);

            accounts.Add(sAcct1);
            accounts.Add(sAcct2);
            accounts.Add(cAcct1);
            accounts.Add(cAcct2);
foreach (Account account in accounts)
            {
                account.Debit(decimal.Parse(Console.ReadLine()));
                account.Credit(decimal.Parse(Console.ReadLine()));
                if (account.GetType().ToString().Contains("SavingsAccount"))
                {
                    //calculate interest if object is a savings account
                }
            }

Answer 1

In this case, probably best to have a default implementation of calculateInterest() in the base class that does nothing.

Subclasses would override to provide account-type-specific interest calculations.