Public Class Form1
    Private Function getMax()
        On Error GoTo getMax_Error
        getMax = TextBox2.Text - 1
        Exit Function

getMax_Error:
        MsgBox("Bitte eine Zahl eingeben!")
    End Function
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs)
        TextBox1.Clear()
        Dim Rnd As New Random
        For i As Integer = 0 To (getMax())
            TextBox1.Text &= Chr(65 + Rnd.Next(0, 9))
        Next
    End Sub

    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs)
        TextBox1.Clear()
        Dim Rnd As New Random
        For i As Integer = 0 To (getMax())
            TextBox1.Text &= Rnd.Next(0, 9)
        Next
    End Sub

    Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs)
        TextBox1.Clear()
        Dim Rnd As New Random
        For i As Integer = 0 To (getMax())
            If Rnd.Next(-5, 5) > 0 Then
                TextBox1.Text &= Chr(65 + Rnd.Next(0, 9))
            Else
                TextBox1.Text &= Rnd.Next(0, 9)
            End If
        Next
    End Sub

    Private Sub Button4_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button4.Click
        If ComboBox1.Text = "Buchstabe" Then
            TextBox1.Clear()
            Dim Rnd As New Random
            For i As Integer = 0 To (getMax())
                If Gerade(i) Then
                    TextBox1.Text &= Chr(Vokale()(Rnd.Next(0, 4)))
                Else
                    TextBox1.Text &= Chr(Konsonanten()(Rnd.Next(0, 20)))

                End If

            Next
        ElseIf ComboBox1.Text = "Zahl" Then
            TextBox1.Clear()
            Dim Rnd As New Random
            For i As Integer = 0 To (getMax())
                TextBox1.Text &= Rnd.Next(0, 9)
            Next
        ElseIf ComboBox1.Text = "Gemischt" Then
            TextBox1.Clear()
            Dim Rnd As New Random
            For i As Integer = 0 To (getMax())
                If Rnd.Next(-300, 300) > 0 Then
                    TextBox1.Text &= Chr(97 + Rnd.Next(0, 25))
                Else
                    TextBox1.Text &= Rnd.Next(0, 9)
                End If
            Next
        ElseIf ComboBox1.Text = "Produktkey-Style" Then
            TextBox1.Clear()
            Dim Rnd As New Random
            For i As Integer = 0 To 15
                If i = 4 Or i = 8 Or i = 12 Then
                    TextBox1.Text &= "-"
                End If
                TextBox1.Text &= Rnd.Next(0, 9)
            Next
        End If
    End Sub
    Function Vokale()
        Dim arr_vok As Integer() = New Integer(4) {97, 101, 105, 111, 117}
        Vokale = arr_vok

    End Function
    Function Konsonanten()
        Dim arr_kon As Integer() = New Integer(20) {98, 99, 100, 102, 103, 104, 106, 107, 108, 109, 110, 112, 113, 114, 115, 116, 118, 119, 120, 121, 122}
        Konsonanten = arr_kon
    End Function
    Function Gerade(ByVal zahl As Integer)
        Gerade = (zahl Mod 2) = 0
    End Function


    Private Sub ComboBox1_SelectedIndexChanged_1(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ComboBox1.SelectedIndexChanged
        If ComboBox1.Text = "Produktkey-Style" Then
            Label1.Hide()
            TextBox2.Hide()
            Label4.Show()
        Else
            Label1.Show()
            TextBox2.Show()
            Label4.Hide()
        End If
    End Sub

    Private Sub Label4_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Label4.Click

    End Sub

    Private Sub TextBox1_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles TextBox1.TextChanged

    End Sub
End Class