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// The abstract base class of the hierarchy.

abstract class Shape

{

protected string shapeName;

public Shape()

{ shapeName = "NoName"; }

public Shape(string s)

{ shapeName = s; }

// A single virtual method.

public virtual void Draw()

{

Console.WriteLine("Inside Shape.Draw()");

}

public string PetName

{

get { return shapeName; }

set { shapeName = value; }

}

}

Notice that the virtual Draw() method provides a default implementation that simply prints out

a message that informs us we are calling the Draw() method within the Shape base class. Now recall

that when a method is marked with the virtual keyword, the method provides a default implemen-

tation that all derived types automatically inherit. If a child class so chooses, it may override the

method but does not 

have to. Given this, consider the following implementation of the Circle and

Hexagon types:

C H A P T E R   6  

■

U N D E R S TA N D I N G   I N H E R I TA N C E  A N D   P O LY M O R P H I S M

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