Question

I am doing homework in C# in which I am implementing the abstract class of Account then I derived two classes form Account named as Saving Account and Checking Account and override some methods in derived classes. Now my problem statement says

Only Instantiate SavingAccount and CheckingAccount Through a reference of Account

Now I am unable to write the code of this because I know the simple object creation but I don’t know how to create an object through the reference of an object. Please tell me some syntax. Thanx

Answer 1

The idea is that an identifier can be the base type:

SomeBaseType identifier;

But when you instantiate it (or new up an instance), you can use any derived type

e.g.

Account account = new SavingsAccount();

EDIT I wanted to add that this is where OOP comes to life (read: “gets really fun!”). Now you can design an interface or contract (such as with an Account class) – and program to the one design. But you may have different account types actually used. With the example I gave, account will continue to look like an Account. Any ‘new’ methods or features in SavingsAccount will not be immediately visiable to code using your account variable. But that’s okay! You don’t want your code to be specifically tailored to SavingsAccount (in MOST cases), you want to instead design a flexible Account that can represent the basic and common features of any Account.