Option Strict On
Public Class Form1
    Inherits System.Windows.Forms.Form

#Region " Windows Form Designer generated code "

    Public Sub New()
        MyBase.New()

        'This call is required by the Windows Form Designer.
        InitializeComponent()

        'Add any initialization after the InitializeComponent() call

    End Sub

    'Form overrides dispose to clean up the component list.
    Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean)
        If disposing Then
            If Not (components Is Nothing) Then
                components.Dispose()
            End If
        End If
        MyBase.Dispose(disposing)
    End Sub
    Friend WithEvents Button1 As System.Windows.Forms.Button
    Friend WithEvents Button2 As System.Windows.Forms.Button

    'Required by the Windows Form Designer
    Private components As System.ComponentModel.Container

    'NOTE: The following procedure is required by the Windows Form Designer
    'It can be modified using the Windows Form Designer.  
    'Do not modify it using the code editor.
    <System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()
        Me.Button1 = New System.Windows.Forms.Button()
        Me.Button2 = New System.Windows.Forms.Button()
        Me.SuspendLayout()
        '
        'Button1
        '
        Me.Button1.Font = New System.Drawing.Font("Verdana", 9.75!, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, CType(0, Byte))
        Me.Button1.Location = New System.Drawing.Point(32, 24)
        Me.Button1.Name = "Button1"
        Me.Button1.Size = New System.Drawing.Size(232, 32)
        Me.Button1.TabIndex = 0
        Me.Button1.Text = "Set up Individual Shapes"
        '
        'Button2
        '
        Me.Button2.Font = New System.Drawing.Font("Verdana", 9.75!, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, CType(0, Byte))
        Me.Button2.Location = New System.Drawing.Point(32, 80)
        Me.Button2.Name = "Button2"
        Me.Button2.Size = New System.Drawing.Size(232, 32)
        Me.Button2.TabIndex = 0
        Me.Button2.Text = "Set up Array of Shapes"
        '
        'Form1
        '
        Me.AutoScaleBaseSize = New System.Drawing.Size(5, 13)
        Me.ClientSize = New System.Drawing.Size(292, 141)
        Me.Controls.AddRange(New System.Windows.Forms.Control() {Me.Button2, Me.Button1})
        Me.Name = "Form1"
        Me.Text = "Shapes Class Test Form"
        Me.ResumeLayout(False)

    End Sub

#End Region

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

        Dim shape1 As New Triangle()
        Dim shape2 As New Circle(4)
        Dim shape3 As New Square(10.01)

        ' SET UP TRIANGLE
        shape1.SideA = 3
        shape1.SideB = 3.2
        shape1.SideC = 0.94

        Dim msg As String
        msg = "The triangle’s area is " & shape1.Area
        msg = msg & vbCrLf & "The circle’s area is " & shape2.Area
        msg = msg & vbCrLf & "The square’s area is " & shape3.Area
        MsgBox(msg)
    End Sub

    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
        Dim aList As New ArrayList()
        aList.Add(New Triangle(3, 3.2, 0.94))
        aList.Add(New Square(10.01))
        aList.Add(New Circle(4))
        Dim shapeEnum As IEnumerator
        Dim totalArea As Double
        shapeEnum = aList.GetEnumerator
        While shapeEnum.MoveNext
            ' If OPTION STRICT = OFF, then the following statement can be written
            ' without explicit casting:
            '        totalArea = totalArea + shapeEnum.Current.Area
            totalArea = totalArea + CType(shapeEnum.Current, Shape).Area
        End While
        MsgBox("The total area of the three shapes is " & totalArea)
    End Sub
End Class