Option Strict On
Public Class Form1
    Inherits System.Windows.Forms.Form
 
    Const pi As Double = 3.14159265
 
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles MyBase.Load
        GroupBox1.Top = 100       'Abstand nach oben
        GroupBox1.Left = 39       'Abstand nach links
        GroupBox2.Top = 100
        GroupBox2.Left = 39
 
        Me.Height = 150           'Größe des Hauptfensters beim Start
        Me.Width = 400
    End Sub
 
    Private Sub Zylinder()
        Static r1, h1 As Integer, a1, v1 As Double
 
        r1 = System.Convert.ToInt32(TextBox1.Text)
        h1 = System.Convert.ToInt32(TextBox2.Text)
 
        a1 = 2 * pi * r1 * (r1 + h1)
        v1 = pi * r1 * r1 * h1
 
        TextBox3.Text = CStr(Math.Round(a1, 2))
        TextBox4.Text = CStr(Math.Round(v1, 2))
    End Sub
 
    Private Sub Kreis()
        Dim r2 As Integer, a2, u As Double
 
        r2 = System.Convert.ToInt32(TextBox5.Text)
 
        a2 = pi * r2 * r2
        u = 2 * pi * r2
 
        TextBox6.Text = CStr(Math.Round(u, 2))
        TextBox7.Text = CStr(Math.Round(a2, 2))
    End Sub
 
    Private Sub ComboBox1_SelectedIndexChanged(ByVal sender As System.Object, _
      ByVal e As System.EventArgs) Handles ComboBox1.SelectedIndexChanged
        Select Case ComboBox1.SelectedIndex
            Case 0
                Me.Height = 568
                Me.Width = 400
                GroupBox1.Visible = True
                GroupBox2.Visible = False
                Zylinder()
            Case 1
                Me.Height = 568
                Me.Width = 400
                GroupBox1.Visible = False
                GroupBox2.Visible = True
                Kreis()
        End Select
    End Sub
 
    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles Button2.Click
        End
    End Sub
End Class