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ArrayListMerge – Merging two ArrayList avoiding duplicate values

ArrayListMerge – Merging two ArrayList avoiding duplicate values

' Merge two ArrayList, avoiding duplicate values (if there are already ' duplicate values in same input ArrayList however, they are not discarded)' ' Example:'   Dim al1 As New ArrayList'   al1.Add("John")'   al1.Add("Ann")'   al1.Add("Frank")''   Dim al2 As New ArrayList'   al2.Add("Ann")'   al2.Add("Tony")'   al2.Add("Mark")'   al2.Add("John")''   Dim al3 As ArrayList = ArrayListMerge(al1, al2)'   Dim o As Object'   Debug.WriteLine("Number of elements in the ArrayList returned from ' ArrayListMerge: " & al3.Count)'   For Each o In al3'       Debug.WriteLine(o)'   NextFunction ArrayListMerge(ByVal al1 As ArrayList, ByVal al2 As ArrayList) As _    ArrayList    ' initialize the capacity to the total count of elements from both array     ' lists    Dim res As New ArrayList(al1.Count + al2.Count)    ' append the items in the first ArrayList    res.AddRange(al1)    Dim o As Object    For Each o In al2        ' add all the al2's elements that are not contained in al1        If Not al1.Contains(o) Then            res.Add(o)        End If    Next    ' trim the ArrayList to the number of actually used slots    res.TrimToSize()    Return resEnd Function

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