Remove Duplicates From A Listbox?

Hi,

Here's an example listbox:

Quote:

---

Hello World
Hi World
Hello World

---

How would I go about removing just one of the "Hello World" entries?

And this also needs to work with multiple duplicated text and without me specifying the duplicates.

Basically I need some code to check through a long listbox, find duplicates and remove them. (if there's 2 duplicates, remove 1, if theres 3 duplicates, remove 2 etc. etc.) I hope I've explained that enough for you to understand.

Code:

---

Private Sub Command1_Click()
Dim i As Long
Dim j As Long
    With List1
        For i = 0 To .ListCount - 1
            For j = .ListCount To (i + 1) Step -1
                If .List(j) = .List(i) Then
                    .RemoveItem j
                End If
            Next
        Next
    End With

End Sub

---

Doing a forum search for "listbox+remove+duplicates" would've given you all these threads.

http://www.vbforums.com/showthread.p...ove+duplicates
http://www.vbforums.com/showthread.p...ove+duplicates
http://www.vbforums.com/showthread.p...ove+duplicates
http://www.vbforums.com/showthread.p...ove+duplicates
http://www.vbforums.com/showthread.p...ove+duplicates
http://www.vbforums.com/showthread.p...ove+duplicates
http://www.vbforums.com/showthread.p...ove+duplicates
http://www.vbforums.com/showthread.p...ove+duplicates
http://www.vbforums.com/showthread.p...ove+duplicates
http://www.vbforums.com/showthread.p...ove+duplicates
http://www.vbforums.com/showthread.p...ove+duplicates
http://www.vbforums.com/showthread.p...ove+duplicates
http://www.vbforums.com/showthread.p...ove+duplicates

The best logic is to prevent the duplicates before they get added to the listbox.

Quote:

---

Originally Posted by RobDog888

The best logic is to prevent the duplicates before they get added to the listbox.

---

Agreed. And, along those lines, this should do the trick.

Code:

---

Option Explicit

Private Declare Function SendMessage Lib "user32" Alias "SendMessageA" _
(ByVal hwnd As Long, _
ByVal wMsg As Long, _
ByVal wParam As Long, _
lParam As Any) As Long

Private Const LB_FINDSTRINGEXACT = &H1A2

Private Sub AddToListbox(strListBItem As String, LB As ListBox)

    Dim lngListIndex As Long
   
    ' lngListIndex is the ListIndex if the item is found
    lngListIndex = SendMessage(LB.hwnd, LB_FINDSTRINGEXACT, -1, ByVal strListBItem)
    If lngListIndex = -1 Then
        LB.AddItem strListBItem
    Else
        MsgBox strListBItem & " is already in the Listbox"
        Exit Sub
    End If
End Sub

Private Sub Command1_Click()
AddToListBox Text1.Text, List1
End Sub

---

No thats not what I meant. If you are populating the listbox with duplicates then change your logic/code to filter and prevent the source from containing any duplictes at all. Like if its a query you can use the SELECT DISTINCT function in your sql depending upon the complexity of your query it will be as simply as that.

vb Code:

Public Sub DeDupeList(ByVal List As ListBox)
    On Error Resume Next
    Dim lstCollection As New Collection
    Dim i As Long
        For i = 0 To List.ListCount - 1
            lstCollection.Add List.List(i), List.List(i)
        Next i
        List.Clear
        For i = 1 To lstCollection.Count
            List.AddItem lstCollection.Item(i)
        Next i
End Sub

Man am I gonna hear it for using On Error Resume Next :lol:

Dont use "On Error Resume Next! Its bad programming practice!!!" :D

Or just use Error Handling for "speed"...Collections are good...if you add a duplicate item (key) to a collection, you get an error.

But, for looping through it, Hack's method using API is the fastest I know of...