Need help with radio buttons within a select case.

[Bucsfan78]

I have to write a program that uses radio buttons to apply a discount to the subtotal. This has to be done with select case. Also, all the discount amounts have to be constants. I have tried many different ways, but after 2 days i give up.

Public Class Form1

Private Sub btnExit_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnExit.Click
Me.Close()
End Sub

Private Sub btnClear_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnClear.Click
txtCoffee.Text = "0"
txtEspresso.Text = "0"
rad0.Checked = True
rad10.Checked = False
rad25.Checked = False
rad50.Checked = False
lblSubtotal.Text = ""
lblTax.Text = ""
lblTotal.Text = ""
End Sub

Private Sub btnCheckout_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnCheckout.Click
Const CONSTCOFFEE As Decimal = CDec(1.95)
Const CONSTESPRESSO As Decimal = CDec(3.95)
Const CONSTTAX As Decimal = CDec(0.07)
Const CONSTDISC0 As Decimal = CDec(0)
Const CONSTDISC10 As Decimal = CDec(0.1)
Const CONSTDISC25 As Decimal = CDec(0.25)
Const CONSTDISC50 As Decimal = CDec(0.5)
Dim intCoffee As Integer = 0
Dim intEspresso As Integer = 0
intCoffee = CInt(txtCoffee.Text)
intEspresso = CInt(txtEspresso.Text)
Dim decSubtotal As Decimal = 0
Dim decTax As Decimal = 0
Dim decTotal As Decimal = 0
Dim decDiscount As Decimal = 0
Dim decPreSubDisc As Decimal = 0

Dim decCalculation As Decimal = 0
Dim decCoffee As Decimal
Dim decEspresso As Decimal
If Decimal.TryParse(txtCoffee.Text, decCoffee) Then
If Decimal.TryParse(txtEspresso.Text, decEspresso) Then
MessageBox.Show("You have ordered " & txtCoffee.Text & " coffee(s)" & ControlChars.CrLf & txtEspresso.Text & " espresso(s).")

Select Case CDec(decDiscount)
Case 1
If rad0.Checked = True Then
decDiscount = CONSTDISC0
End If

Case 2
If rad10.Checked = True Then
decDiscount = CONSTDISC10
End If

Case 3
If rad10.Checked = True Then
decDiscount = CONSTDISC25
End If

Case 4
If rad10.Checked = True Then
decDiscount = CONSTDISC50
End If
End Select




decPreSubDisc = CDec((CONSTCOFFEE * intCoffee) + (CONSTESPRESSO * intEspresso))
decSubtotal = CDec(decPreSubDisc - (((CONSTCOFFEE * intCoffee) + (CONSTESPRESSO * intEspresso)) * decDiscount))
lblSubtotal.Text = decSubtotal.ToString("c")
decTax = CDec(decSubtotal * CONSTTAX)
lblTax.Text = decTax.ToString("c")
decTotal = CDec(decSubtotal + decTax)
lblTotal.Text = decTotal.ToString("c")

End If

Else : MessageBox.Show("Please enter numbers only")
txtCoffee.Text = "0"
txtEspresso.Text = "0"
End If

End Sub
End Class

[norman_bates]

I would replace your current Select Case with

              Select Case Rad0.Checked
                    Case True
                        decDiscount = CONSTDISC0
                    Case Else
                        Select Case Rad10.Checked
                            Case True
                                decDiscount = CONSTDISC10
                            Case Else
                                Select Case Rad25.Checked
                                    Case True
                                        decDiscount = CONSTDISC25
                                    Case Else
                                        Select Case Rad50.Checked
                                            Case True
                                                decDiscount = CONSTDISC50
                                        End Select
                                End Select
                        End Select
                End Select

[Españolita]

The example from norman_bates above solves the problem but it leaves me with a bigger problem. Select Case is not designed to check values of different variables or objects. As you have already realised, it checks a SINGLE variable for different values and deals with each case accordingly, therefore it is not an appropriate solution to the problem you have identified. If .... Then ... ElseIf is much better in this situation.
The situation you described is contrived and, I'm sorry, to me pretty ridiculous.
I would go back and check again exactly what the assignment requires.

oh no! I'm starting to sound like DataMiser now

[Inferrd]

Select Case True ?

[Españolita]

Select Case True ?

OH yes! I never even thought of that!. Feel pretty daft now for the rant But I still think it's convoluted.

[dbasnett]

@OP

'

        'instead of
        Const CONSTCOFFEE As Decimal = CDec(1.95)

        'do this and save some typing
        Const CONSTCOFFEE As Decimal = 1.95D
        '

[Bucsfan78]

Select Case True ?

That it, I knew I was overlooking something simple. This worked perfect.

Select Case True
Case rad0.Checked
decDiscount = CONSTDISC_0
Case rad10.Checked
decDiscount = CONSTDISC_10
Case rad25.Checked
decDiscount = CONSTDISC_25
Case rad50.Checked
decDiscount = CONSTDISC_50
End Select

Thanks so much.

[dbasnett]

Another approach would be to put the discount associated with each RadioButton(RB) into the .Tag property of the RB. Then set up one .CheckedChanged event handler to set the discount based on the Tag. Here is what it might look like. Note that I only did two buttons.

    Dim decDiscount As Decimal
    Private Sub RadioButton_CheckedChanged(sender As Object, _
                                           e As EventArgs) _
                                       Handles rad10.CheckedChanged, rad25.CheckedChanged
        Dim rb As RadioButton = DirectCast(sender, RadioButton) 'get the radio button affected
        If rb.Checked Then 'is it checked
            'yes, get the discount from the tag
            decDiscount = Decimal.Parse(DirectCast(rb.Tag, String))
        End If
    End Sub

Add the other radio.CheckedChanged and you will be done.