listbox and checkboxes

[Eena]

Hello...

The user is shopping for a computer...
After having several items in the listbox, user decided not to include the Zip Drive.

Form1: Has all the combo boxes; listboxes and checkboxes

Form2: is the receipt where it shows all the selected items and the prices for each selection, except for the
lstComponents (a listbox populated from checkbox selection) which will only show a subtotal for all the addidtional components (zipDrive, DVD, modem, cdrom,etc...)

I tried using the code below for deleting a previously selected item (checked from the checkbox and was then
additem into the listbox).

Here's my code in Form1:

Private Sub chkZipDrive_Click()
If frmComputerSales.chkZipDrive.Value = 1 Then
frmReceipt.lstComponents.AddItem "Zip Drive"
booZipDrive = True
intzipdrive = consZipDrive
Else
booZipDrive = False
intzipdrive = 0
frmReceipt.lstComponents.clear 'tried this one and it obviously cleared the whole listbox... I only wanted to clear the "Zip Drive" if it is unchecked by user...

End If
End Sub


Thanks,

[mattbrown]

When you call the addItem method of the list box there is a second parameter you can pass to it. This index parameter marks that item and you can then call the removeItem method of the list box passing it the index of the item you want to remove.

ie.

Dim zipIndex as integer
zipIndex = 0 'or any other unique integer
Private Sub chkZipDrive_Click()
    If chkZipDrive.Value = vbChecked Then
        frmReceipt.lstComponents.AddItem "Zip Drive", zipIndex
    Else
        frmReceipt.lstComponents.RemoveItem zipIndex
    End If
End Sub

The only requirement is that each item in the list box has a unique id. So it would be a good idea to assign each component that may possibly feature in the list box a number to use as it's index and then go off that.

[Eena]

Hi Matt..

The code below gave me an error..."Invalid procedure call or argument"...

Private Sub chkZipDrive_Click()
Dim zipindex As Integer
zipindex = 2
If frmComputerSales.chkZipDrive.Value = 1 Then
frmReceipt.lstComponents.AddItem "Zip Drive", 2
intZipDrive = consZipDrive
Else

frmReceipt.lstComponents.RemoveItem zipindex
intZipDrive = 0

End If
End Sub


Also, when checkbox is unchecked... it deleted the wrong item... that happen to be in that index parameter...

We have to consider that the user is clicking randomly...and will be checking and unchecking (back and forth)until they decide the final selection and
an affordable total...

Is there any other code that will work with this scenario??

Thanks,

[mattbrown]

Sorry just remembered an important detail that I left out before.

When assigning index numbers to the items in a list they MUST follow the 0, 1, 2, 3 .... sequence

You cannot have and item 3 then 2, 7, 0 etc. You must have them numbered from 0 up.

That will be the cause of the "Invalid procedure call or argument" error as you are trying to make it no 2.

You could store the items list index number in the controls tag property. eg.

Private Sub chkZipDrive_Click() 
  Dim zipindex As Integer 
  zipindex = frmReceipt.lstComponents.listCount - 1
  If frmComputerSales.chkZipDrive.Value = 1 Then 
    frmReceipt.lstComponents.AddItem "Zip Drive", zipIndex
    chkZipDrive.tag = zipIndex
  Else 
    If chkZipDrive.tag <> - 1 Then 
      frmReceipt.lstComponents.RemoveItem chkZipDrive.tag
      chkZipDrive.tag = -1
    End If
  End If 
End Sub

Haven't tested the above code as I don't have VB with me but it should work.

You'll see that I have also added a check to stop it removing the item if it has already been removed.

[Eena]

Hi Matt...

Copied and pasted the code you typed and it still gave me the same call argument error...

Any other suggestions?

Thanks,

[mattbrown]

Not really

Just ensure that the item you are adding is next in numerical order.

If that doesn't work step through the code, line by line and tell me the exact line that it crashes on.