Remove duplicate from ListBox

Hi All,

I'm sure this is easy to answer but I can not figureit out.

I am getting an OutOfBoundException when I run this loop that loops
through the listbox in question and looks for duplicate values. Could
anyone shed any light on this?


For intListCountF As integer = 0 to frmPlayer.Listbox1.ListCount -1
For intListCountB As Integer = frmPlayer.Listbox1.Listcount -1 to 0
Step -1
if frmplayer.Listbox1.List(intListCountB) =
frmPlayer.Listbox1.List(intListCountF) Then
frmplayer.Listbox1.RemoveRow(intListCountB)
end if
Next
Next

Cheers,
Liam.

Liam Whan <liam.whan@gmail.com> wrote in news:4fc21f6f$0$1762$c3e8da3
$92d0a893@news.astraweb.com:

> Hi All,
>
> I'm sure this is easy to answer but I can not figureit out.
>
> I am getting an OutOfBoundException when I run this loop that loops
> through the listbox in question and looks for duplicate values. Could
> anyone shed any light on this?
>
>
> For intListCountF As integer = 0 to frmPlayer.Listbox1.ListCount -1
> For intListCountB As Integer = frmPlayer.Listbox1.Listcount -1 to
0
> Step -1
> if frmplayer.Listbox1.List(intListCountB) =
> frmPlayer.Listbox1.List(intListCountF) Then
> frmplayer.Listbox1.RemoveRow(intListCountB)
> end if
> Next
> Next
>
> Cheers,
> Liam.
>

Because you're reducing the number of rows in the listbox while still
indexing on the original number of rows. At some point you will try to
access a row number that no longer exists in the listbox.


--
Dale M. Arends
dalearends@sbcglobal.net

Liam Whan wrote:

> I'm sure this is easy to answer but I can not figureit out.
>
> I am getting an OutOfBoundException when I run this loop that loops
> through the listbox in question and looks for duplicate values. Could
> anyone shed any light on this?
>
>
> For intListCountF As integer = 0 to frmPlayer.Listbox1.ListCount -1
> For intListCountB As Integer = frmPlayer.Listbox1.Listcount -1 to 0
> Step -1
> if frmplayer.Listbox1.List(intListCountB) =
> frmPlayer.Listbox1.List(intListCountF) Then
> frmplayer.Listbox1.RemoveRow(intListCountB)
> end if
> Next
> Next

You're clearing your list. When intListCountF has the same value as
intListCountB, you're removing the item. Since you will get to *every* value
in the list in both For loops, you will remove *everything*. Eventually
you're left with a list containing zero items.

Try something like this (untested air code):

For intListCountF As Integer = 0 To frmPlayer.Listbox1.ListCount - 2
For intListCountB As Integer = frmPlayer.Listbox1.ListCount - 1 To _
intListCountF + 1 Step -1
If frmplayer.Listbox1.List(intListCountB) = _
frmPlayer.Listbox1.List(intListCountF) Then
frmplayer.Listbox1.RemoveRow(intListCountB)
End If
Next
Next

--
- Can we talk about this next week?
- Just one more thing...
- Is it next week already?!

On 28/05/2012 7:41 AM, Auric__ wrote:
> Liam Whan wrote:
>
>> I'm sure this is easy to answer but I can not figureit out.
>>
>> I am getting an OutOfBoundException when I run this loop that loops
>> through the listbox in question and looks for duplicate values. Could
>> anyone shed any light on this?
>>
>>
>> For intListCountF As integer = 0 to frmPlayer.Listbox1.ListCount -1
>> For intListCountB As Integer = frmPlayer.Listbox1.Listcount -1 to 0
>> Step -1
>> if frmplayer.Listbox1.List(intListCountB) =
>> frmPlayer.Listbox1.List(intListCountF) Then
>> frmplayer.Listbox1.RemoveRow(intListCountB)
>> end if
>> Next
>> Next
> You're clearing your list. When intListCountF has the same value as
> intListCountB, you're removing the item. Since you will get to *every* value
> in the list in both For loops, you will remove *everything*. Eventually
> you're left with a list containing zero items.
>
> Try something like this (untested air code):
>
> For intListCountF As Integer = 0 To frmPlayer.Listbox1.ListCount - 2
> For intListCountB As Integer = frmPlayer.Listbox1.ListCount - 1 To _
> intListCountF + 1 Step -1
> If frmplayer.Listbox1.List(intListCountB) = _
> frmPlayer.Listbox1.List(intListCountF) Then
> frmplayer.Listbox1.RemoveRow(intListCountB)
> End If
> Next
> Next
>
Of Course!

I'm an idiot! Thanks so much guys.

what I eventually went with was an algorithim that -1 off the row count
every time it removed a row.

Thanks again!

Liam