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

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

    '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.
    Friend WithEvents Label1 As System.Windows.Forms.Label
    Friend WithEvents TxtSize As System.Windows.Forms.TextBox
    Friend WithEvents txtArea As System.Windows.Forms.TextBox
    Friend WithEvents Label2 As System.Windows.Forms.Label
    Friend WithEvents TxtPerim As System.Windows.Forms.TextBox
    Friend WithEvents Label3 As System.Windows.Forms.Label
    Friend WithEvents BtnCalc As System.Windows.Forms.Button
    <System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()
        Me.Label1 = New System.Windows.Forms.Label
        Me.TxtSize = New System.Windows.Forms.TextBox
        Me.txtArea = New System.Windows.Forms.TextBox
        Me.Label2 = New System.Windows.Forms.Label
        Me.TxtPerim = New System.Windows.Forms.TextBox
        Me.Label3 = New System.Windows.Forms.Label
        Me.BtnCalc = New System.Windows.Forms.Button
        Me.SuspendLayout()
        '
        'Label1
        '
        Me.Label1.Font = New System.Drawing.Font("Microsoft Sans Serif", 9.75!, System.Drawing.FontStyle.Bold, System.Drawing.GraphicsUnit.Point, CType(0, Byte))
        Me.Label1.Location = New System.Drawing.Point(24, 24)
        Me.Label1.Name = "Label1"
        Me.Label1.Size = New System.Drawing.Size(48, 32)
        Me.Label1.TabIndex = 0
        Me.Label1.Text = "Size"
        '
        'TxtSize
        '
        Me.TxtSize.Location = New System.Drawing.Point(80, 24)
        Me.TxtSize.Name = "TxtSize"
        Me.TxtSize.Size = New System.Drawing.Size(96, 20)
        Me.TxtSize.TabIndex = 1
        Me.TxtSize.Text = ""
        '
        'txtArea
        '
        Me.txtArea.Location = New System.Drawing.Point(88, 72)
        Me.txtArea.Name = "txtArea"
        Me.txtArea.ReadOnly = True
        Me.txtArea.Size = New System.Drawing.Size(96, 20)
        Me.txtArea.TabIndex = 3
        Me.txtArea.Text = ""
        '
        'Label2
        '
        Me.Label2.Font = New System.Drawing.Font("Microsoft Sans Serif", 9.75!, System.Drawing.FontStyle.Bold, System.Drawing.GraphicsUnit.Point, CType(0, Byte))
        Me.Label2.Location = New System.Drawing.Point(32, 72)
        Me.Label2.Name = "Label2"
        Me.Label2.Size = New System.Drawing.Size(48, 32)
        Me.Label2.TabIndex = 2
        Me.Label2.Text = "Area"
        '
        'TxtPerim
        '
        Me.TxtPerim.Location = New System.Drawing.Point(80, 112)
        Me.TxtPerim.Name = "TxtPerim"
        Me.TxtPerim.ReadOnly = True
        Me.TxtPerim.Size = New System.Drawing.Size(96, 20)
        Me.TxtPerim.TabIndex = 5
        Me.TxtPerim.Text = ""
        '
        'Label3
        '
        Me.Label3.Font = New System.Drawing.Font("Microsoft Sans Serif", 9.75!, System.Drawing.FontStyle.Bold, System.Drawing.GraphicsUnit.Point, CType(0, Byte))
        Me.Label3.Location = New System.Drawing.Point(0, 112)
        Me.Label3.Name = "Label3"
        Me.Label3.Size = New System.Drawing.Size(72, 32)
        Me.Label3.TabIndex = 4
        Me.Label3.Text = "Perimeter"
        '
        'BtnCalc
        '
        Me.BtnCalc.Location = New System.Drawing.Point(200, 24)
        Me.BtnCalc.Name = "BtnCalc"
        Me.BtnCalc.Size = New System.Drawing.Size(64, 32)
        Me.BtnCalc.TabIndex = 6
        Me.BtnCalc.Text = "Calculate"
        '
        'Form1
        '
        Me.AutoScaleBaseSize = New System.Drawing.Size(5, 13)
        Me.ClientSize = New System.Drawing.Size(292, 273)
        Me.Controls.Add(Me.BtnCalc)
        Me.Controls.Add(Me.TxtPerim)
        Me.Controls.Add(Me.Label3)
        Me.Controls.Add(Me.txtArea)
        Me.Controls.Add(Me.Label2)
        Me.Controls.Add(Me.TxtSize)
        Me.Controls.Add(Me.Label1)
        Me.Name = "Form1"
        Me.Text = "Form1"
        Me.ResumeLayout(False)

    End Sub

#End Region

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

        Dim square1 As square
        square1 = New square(5) ' create a square (instantiate)
        MsgBox(square1.Length)
        square1.Length = 17
        MsgBox(square1.Length)
        square1.Length = -17
        MsgBox(square1.Length)
        Dim area As Double
        area = square1.calcArea()
        MsgBox("area: " & area)
        Dim square2 As square
        square2 = New square(-5)
        MsgBox(square2.Length)
    End Sub

    Private Sub BtnCalc_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles BtnCalc.Click
        Dim square1 As square
        If IsNumeric(TxtSize.Text) Then
            Dim size = Convert.ToDouble(TxtSize.Text)
            If size > 0 Then
                square1 = New square(size)
                Dim area As Double = square1.calcArea()
                txtArea.Text = area.ToString("n1")
                Dim perim As Double
                perim = square1.calcPerimeter()
                TxtPerim.Text = perim.ToString("n1")

            End If
        End If
    End Sub
End Class