[2005] Class Inheritance

[DekaFlash]

I have the following class definition

Public Class Car
    Public ReadOnly MaxSpeed As Integer
    Private CurrSpeed As Integer

    Public Sub New()

    End Sub
    Public Sub New(ByVal max As Integer)
        MaxSpeed = 55
    End Sub

    Public Property Speed() As Integer
        Get
            Return CurrSpeed
        End Get
        Set(ByVal value As Integer)
            CurrSpeed += value
            If CurrSpeed > MaxSpeed Then
                CurrSpeed = MaxSpeed
            End If
        End Set
    End Property
End Class

Public Class MiniVan
    Inherits Car

End Class

In the main code I access it as follows

Module Module1

    Sub Main()
        Dim myCar As New Car(80)
        myCar.Speed = 50
        Console.WriteLine("My car is going {0} MPH", myCar.Speed)
        Console.WriteLine()

        Dim myVan As New MiniVan()
        myVan.Speed = 10
        Console.WriteLine("My van is going {0} MPH", myVan.Speed)
        Console.WriteLine()
        Console.ReadLine()
    End Sub

End Module

When I run the Console App, I get the following output but I believe I should be getting - My van is going 10 mph.

My car is going 50 MPH

My van is going 0 MPH

Can somebody please explain, where I am going wrong?

Thanks
Edit/Delete Message

[keystone_paul]

At a glance...

When you declare myVan you aren't passing in a maximum speed unlike when you declare myCar, so it is defaulting max speed to zero.

[jmcilhinney]

If you had used the debugger you'd have seen exactly what keystone_paul said. If you'd placed a breakpoint on the Set method of the Speed property you'd have seen that execution enters the If block, because CurrSpeed is greater than MaxSpeed, and sets CurrSpeed to the value of MaxSpeed, which is zero.

The debugger exists so you can debug your code, so you should make use of it. The first tools you need to use are breakpoints (F9), which halt execution at a specific line of code, and then Step Over (F10) and Step Into (F11), which let you step through your code one line at a time. At each step you can mouse over variables and properties to determine their value, use the Autos, Locals, Watch and Immediate windows to evaluate variables, properties, methods and expressions and use the Command window to execute code.