Professional C# 2012 and .NET 4.5

Chapter 4

Inheritance

WHAT’S IN THIS CHAPTER?

• Types of inheritance
• Implementing inheritance
• Access modifiers
• Interfaces

WROX.COM CODE DOWNLOADS FOR THIS CHAPTER

The wrox.com code downloads for this chapter are found at http://www.wrox.com/remtitle.cgi?isbn=1118314425 on the Download Code tab. The code for this chapter is divided into the following major examples:

• BankAccounts.cs
• CurrentAccounts.cs
• MortimerPhones.cs

INHERITANCE

Chapter 3, “Objects and Types,” examined how to use individual classes in C#. The focus in that chapter was how to define methods, properties, constructors, and other members of a single class (or a single struct). Although you learned that all classes are ultimately derived from the class System.Object, you have not yet learned how to create a hierarchy of inherited classes. Inheritance is the subject of this chapter, which explains how C# and the .NET Framework handle inheritance.

TYPES OF INHERITANCE

Let’s start by reviewing exactly what C# does and does not support as far as inheritance is concerned.

Implementation Versus Interface Inheritance

In object-oriented programming, there are two distinct types of inheritance — implementation inheritance and interface inheritance:

• Implementation inheritance means that a type derives from a base type, taking all the base type’s member fields and functions. With implementation inheritance, a derived type adopts the base type’s implementation of each function, unless the definition of the derived type indicates ...