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// Define the application object as static.

static class Program

{

static void Main(string[] args)

{

...

}

}

At this point in the chapter you hopefully feel comfortable defining simple class types contain-

ing constructors, fields, and various static (and nonstatic) members. Now that you have the basics

under your belt, we can formally investigate the three pillars of object-oriented programming.

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Source Code

The StaticData project is located under the Chapter 5 subdirectory.

Defining the Pillars of OOP

All object-based languages must contend with three core principals of object-oriented program-

ming, often called the “pillars of object-oriented programming (OOP)”:

C H A P T E R   5  

■

D E F I N I N G   E N C A P S U L AT E D   C L A S S  T Y P E S

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• Encapsulation: How does this language hide an object’s internal implementation details and

preserve data integrity?

•

Inheritance: How does this language promote code reuse?

•

Polymorphism: How does this language let you treat related objects in a similar way?

Before digging into the syntactic details of each pillar, it is important that you understand the

basic role of each. Here is an overview of each pillar, which will be examined in full detail over the

remainder of this chapter and the next.