I'm attempting to figure volumes for a box,cylinder, cone and sphere.  I have set up a combo box with all four shapes in the combo box.  I name named this combo box, "cbshape".  Can someone help or advise how to write code for:  when a shape is selected from combo box to perform the volume formula for that shape, and post the volume in a read-only text box names"txtvolume".  

I have setup this program and reading through the text I'm not exactly sure where to start or evern how to start the real coding to figure the volume per shape selected.  I know that I have to use a if, the, else and nest a few if's inside the first if to complete this program.  Like I said I'm just not sure to code to get the program to read from the combo box, to perform the corrort volume formula.   ANY HELP WOULD BE GREAT!!!
thanks  

Instead of "If"s I might use a "Select Case" because this can make  for easier reading, especially if things get nested...which I am not sure why it would in this case, but anyways here's a bit to get you started...

In the code that initiates the computation (like a Command Button click event, or the Combo Box Selection Changed event) Dim theValue As Double MsgBox(ComputeVolume(cbshape.SelectedItem)) Then, then code a "ComputeVolume" Function to do the work... Function ComputeVolume(ByVal pShape As String) As Double Dim retVal As Double = 0 Select Case cbshape.SelectedItem Case "cube"     retval = some formula... Case "cylinder"    retval = some formula... Case "cone"    retval = some formula... Case "sphere"    retval = some formula... Case Else    End Select Return retVal End Function

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I will be doing this tonight, thank you very very much for the help.  I knew I had to do something with the ".selecteditem", but like i said.. I wasn't sure where and what to do..
thanks again, and I will let you know how it goes!!


[Edited by echoes915 on 27-10-2006 at 04:53 PM GMT]

I can't write a function...I'm not advanced and the book no where talks about functions yet..however this is what i put together, and i'm not getting any output to the txtvolume box...can someone tell me my errors?

  Dim txtheight As Integer
        Dim txtlegnth As Integer
        Dim txtwidth As Integer
        Dim txtradius As Integer
        Dim strvolumebox As Integer
        Dim strvolumecone As Integer
        Dim strvolumecylinder As Integer
        Dim strvolumesphere As Integer
        If cbShape.Text = "" Then
            MessageBox.Show("Please select a shape from the options!", "No shape selected", MessageBoxButtons.OK, MessageBoxIcon.Exclamation)
            cbShape.Focus()
        End If
      
        Select Case cbShape.SelectedIndex
            Case "box"
                strvolumebox = txtlegnth * txtwidth * txtheight"
            Case "Cone"
                strvolumecone = (3.14 * txtradius * txtradius * txtheight) / 3
            Case "Cylinder"
                strvolumecylinder = 3.14 * txtradius * txtradius * txtheight
            Case "Sphere"
                strvolumesphere = 4 * 3.14 * txtradius * txtradius * txtradius / 3
        End Select
        If cbShape.SelectedIndex = "box" Then
            txtvolume.Text = strvolumebox
        Else
            If cbShape.SelectedIndex = "cone" Then
                txtvolume.Text = strvolumecone
            Else
                If cbShape.SelectedIndex = "Cylinder" Then
                    txtvolume.Text = strvolumecylinder
                Else
                    If cbShape.SelectedIndex = "Sphere" Then
                        txtvolume.Text = strvolumesphere
                    End If
                End If
            End If

        End If
    End Sub


that is where i'm at.... just let me know what i'm doing wrong, or where i have done wrong!
thanks again tons

Hey im surprised that you didnt get any errors i think your option strict is turned off

Anyways you cant compare "SelectedIndex" to your criterias because its a number (int32). (try using the index of your items on your list)

for example if you added the following to the items property on your combo box:

0 box
1 cone
2 cylinder
3 sphere

then you should use 0 as a criteria for your box,1 for cone, and so on...



If you still would want to compare strings on combo box...follow these steps


'----Create a structure (and declare it)

Public Structure YourStructure
  Private HiddenName as system.string
  Private HiddenValue as System.string

Public Property DisplayName as System.string
Get
return HiddenName
End Get
Set (Byval sval as system.string)
HiddenName = sval
End Set
End Property

Public Property ValueName as System.string
Get
return HiddenValue
End Get
Set (Byval sval as system.string)
HiddenValue = sval
End Set
End Property
End Structure

Private MyShapeSelections(3) as YourStructure


'----------------write these to any intialization event


MyShapeSelections(0).DisplayName  = "Box"
MyShapeSelections(0).ValueName  = "box"

MyShapeSelections(1).DisplayName  = "Cone"
MyShapeSelections(1).ValueName  = "cone"

MyShapeSelections(2).DisplayName  = "Cylinder"
MyShapeSelections(2).ValueName  = "cylinder""

MyShapeSelections(3).DisplayName  = "Sphere"
MyShapeSelections(3).ValueName  = "sphere"

'----- bind these to your combobox

yourcombobox.datasource=MyShapeSelections
yourcombobox.displayvalue="DisplayName"
yourcombobox.valuemember="ValueName"



'-------Reminder
in this case you cant use the "selectedindexchanged" event...use the "selectedvaluechanged" event.
From here you can use the selectedValue for your criteria

Select Case yourcombobox.selectedvalue
Case "box"
'run your formula
Case "cone"
'run your formula
case "cylinder"
'run your formula
case "sphere"
'run your formula
case else
'go for launch
end select


nice huh? thats called databinding

or you can just follow the instructions of "bean"... its alot easier

[Edited by Nick2k3 on 02-11-2006 at 08:53 PM GMT]

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