Deleting duplicate entries within an list

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I have a problem,

I need to delete duplicate entries in an List that I created.
The list is classed as an object and each line has multiple entries.

Can anyone give me any guidance or tutorials to try, because everything that I have tried so far hasn't worked?
(I have searched on Google, and no success)

I know I can't use For Each...Next because you cannot delete entries in an IEnumerable list, however using a For Next loop brings up an error. i.e:

VB

For i As Integer = 0 To mylist.Items.Count - 1 Step 1

Posted 14-Sep-12 4:24am

Willtwinny

Updated 14-Sep-12 4:25am

v3

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Kenneth Haugland · Answer 1 · 2012-09-14T04:26:00

Solution 1

The list remove was created for this purpose, however it deletes the first simular item in the list:
http://msdn.microsoft.com/en-us/library/cd666k3e.aspx[^]

Posted 14-Sep-12 4:26am

Kenneth Haugland

Huseyin Atasoy · Answer 2 · 2012-09-15T05:06:00

I couldn't understand what you mean by "List". "List(Of T)" or "ListBox" or something else...
So I will give a general answer.
When you remove an item from a list, item count of this list decreases. This is why fixed loops don't work as expected. I wrote a method below that removes duplicated items in a ListBox object. You can adapt this method to your purpose...

VB

Private Sub RemoveDupItems(ByRef ListBoxObj As ListBox)
    Dim ItemCount As Integer = ListBoxObj.Items.Count
    Dim Position1 As Integer = 0

    While (Position1 < ItemCount)
        Dim Position2 As Integer = 0
        While (Position2 < ItemCount)
            If Position1 <> Position2 Then
                If ListBoxObj.Items(Position1) = ListBoxObj.Items(Position2) Then
                    ListBoxObj.Items.RemoveAt(Position2)
                    ItemCount -= 1
                    Exit While
                End If
            End If
            Position2 += 1
        End While
        Position1 += 1
    End While
End Sub

Usage example:

VB

RemoveDupItems(ListBox1)