Visual Basic

Public MustInherit Class Quadrilateral
    Public Function getName() As String
        Return "Shape"
    End Function
    Public Function Area() As Double
        Return 0
    End Function
End Class
Public MustInherit Class Twodimensional
    Inherits Quadrilateral

    Private Mx As Integer
    Private y As Integer
    Public Sub New(ByVal xValue As Integer, ByVal yValue As Integer)
        Mx = xValue
        y = yValue
    End Sub
    Public Property xpoint() As Integer
        Get
            Return Mx
        End Get
        Set(ByVal value As Integer)
            Mx = value
        End Set
    End Property
    Public Property Ypoint() As Integer
        Get
            Return y
        End Get
        Set(ByVal value As Integer)
            y = value
        End Set
    End Property
End Class

Public Class Square
    Inherits Twodimensional


    Public sd As Double

    Public Sub New()
        MyBase.New(0, 0)
        Side = 0
    End Sub

    Public Sub New(ByVal xValue As Integer, ByVal yValue As Integer, ByVal side As Double)
        MyBase.New(xValue, yValue)
        sd = side
    End Sub

    Public Property Side() As Double
        Get
            Return sd
        End Get
        Set(ByVal Value As Double)
            If Value <= 0 Then
                sd = 0
            Else
                sd = Value
            End If
        End Set
    End Property
    Public Overloads Function Area() As Double
        Return sd * sd
    End Function

    Public Overloads Function getName() As String

        Return "Square"

    End Function
End Class
Public Class Rectangle
    Inherits Twodimensional


    Public height As Double
    Public wdith As Double

    Public Sub New()
        MyBase.New(0, 0)
        height = 0
        wdith = 0
    End Sub

    Public Sub New(ByVal xValue As Integer, ByVal yValue As Integer, ByVal height As Double, ByVal wdith As Double)
        MyBase.New(xValue, yValue)
        height = height
        wdith = wdith
    End Sub

    Public Property h() As Double
        Get
            Return height
        End Get
        Set(ByVal Value As Double)
            If Value <= 0 Then
                height = 0
            Else
                height = Value
            End If
        End Set
    End Property
    Public Property W() As Double
        Get
            Return wdith
        End Get
        Set(ByVal Value As Double)
            If Value <= 0 Then
                wdith = 0
            Else
                wdith = Value
            End If
        End Set
    End Property
    Public Overloads Function Area() As Double
        Return 2 * (height * wdith)
    End Function

    Public Overloads Function getName() As String

        Return "Rec"

    End Function
End Class



Module Module1
    Sub main()
        Dim i As Integer
        Dim shapes(1) As Quadrilateral

        shapes(0) = New Square(0, 0, 5)
        shapes(1) = New Rectangle(1, 1, 2, 10)
        For i = 0 To shapes.GetUpperBound(0)
            If TypeOf shapes(i) Is Twodimensional Then
                Dim shape As Twodimensional = _
                CType(shapes(i), Twodimensional)
                Console.WriteLine("Two:" & vbCrLf & "Name: " & vbTab & _
                                  "{0}" & vbCrLf & "Values: " & vbTab & _
                                  "{1}" & vbCrLf & "Area: " & vbTab & _
                                  "{2}" & vbCrLf, shape.getName(), shape.Area())
            Else
                Console.WriteLine("No such shape")
            End If

        Next
    End Sub

End Module