Visual Basic.NET How to Program (PDF)

368 Object-Oriented Programming: Inheritance Chapter 9
14 ' get CCircle3's initial x-y coordinates and radius
15 output = "X coordinate is " & circle.X & vbCrLf & _
16 "Y coordinate is " & circle.Y & vbCrLf & "Radius is " & _
17 circle.Radius
18
19 ' set CCircle3's x-y coordinates and radius to new values
20 circle.X = 2
21 circle.Y = 2
22 circle.Radius = 4.25
23
24 ' display CCircle3's String representation
25 output &= vbCrLf & vbCrLf & _
26 "The new location and radius of circle are " & _
27 vbCrLf & circle.ToString() & vbCrLf
28
29 ' display CCircle3's diameter
30 output &= "Diameter is " & _
31 String.Format("{0:F}", circle.Diameter()) & vbCrLf
32
33 ' display CCircle3's circumference
34 output &= "Circumference is " & _
35 String.Format("{0:F}", circle.Circumference()) & vbCrLf
36
37 ' display CCircle3's area
38 output &= "Area is " & String.Format("{0:F}", circle.Area())
39
40 MessageBox.Show(output, "Demonstrating Class CCircle3")
41 End Sub ' Main
42
43 End Module ' modCircleTest3
Fig. 9.11 modCircleTest3 demonstrates class CCircle3 functionality
(part 2 of 2).
Software Engineering Observation 9.6
Declaring base-class instance variables Private (as opposed to declaring them Protected)
helps programmers change base-class implementation without having to change
derived-class implementation. 9.6