Excel VBA Create a list and add only unique terms - arrays

Question

I am trying to pull strings from column A and move them to column B only if they don't already exist in column B. To do this, I wanted to make a list and scan all of column A with it, however, I'm not sure how to do that in VBA. In python I recall using something along the lines of
[If (x) not in (List)]
but that same approach isnt working for me in Excel.
Currently, I have the following
Sub GatherAll()
GL = List()
rwcnt = WorksheetFunction.CountA(Range("A:A"))
lastc = Cells(1, Columns.Count).End(xlToLeft).Column
Dim i As Long
For i = 2 To rwcnt
Cells(i, 1).Value = n
and I want to say something like
if n not in GL, GL.append(n)
continue
End Sub
If anyone could help me out, I would really appreciate it.

Answer 1

Try adapting the following code to your exact needs and see if it helps. If you need help, let us know.
Sub MoveUniqueEntries()
Dim oDict As Object
Dim rToMove As Range
Dim rDest As Range
Dim rLoop As Range
Set oDict = CreateObject("Scripting.Dictionary")
Set rToMove = Intersect(Sheet1.Range("A1").CurrentRegion, Sheet1.Columns(1))
Set rDest = Sheet1.Range("B1")
For Each rLoop In rToMove
If oDict.exists(rLoop.Value) Then
'Do nothing
Else
oDict.Add rLoop.Value, 0
rDest.Value = rLoop.Value
Set rDest = rDest.Offset(1)
End If
Next rLoop
End Sub

Answer 2

In your VBA IDE you will have to add a reference. On the tools pulldown menu select references. Then select "Microsoft ActiveX Data Objects 2.8 Library".
Dim rs As New ADODB.Recordset
Dim ws As Excel.Worksheet
Dim lRow As Long
Set ws = Application.ActiveSheet
'Add fields to your recordset for storing data. You can store sums here.
With rs
.Fields.Append "Row", adInteger
.Fields.Append "Value", adInteger
.Open
End With
lRow = 1
'Loop through and record what is in the first column
Do While lRow <= ws.UsedRange.Rows.count
rs.AddNew
rs.Fields("Row").Value = lRow
rs.Fields("Value").Value = ws.Range("A" & lRow).Value
rs.Update
lRow = lRow + 1
ws.Range("A" & lRow).Activate
Loop
'Now go through and list out the unique values in columnB.
lRow = 1
rs.Sort = "value"
Do While lRow <= ws.UsedRange.Rows.count
if rs.Fields("value").Value <> strLast then
ws.Range("B" & lRow).Value = rs.Fields("value").Value
lRow = lRow + 1
End if
strLast = rs.Fields("value").Value
Loop

Answer 3

Cross-platform version (but will be slow for large numbers of values):
Sub UniquesTester()
Dim v, u(), i As Long, n As Long
n = 0
v = Range(Range("A1"), Cells(Rows.Count, 1).End(xlUp)).Value
ReDim u(1 To UBound(v, 1))
For i = 1 To UBound(v, 1)
If IsError(Application.Match(v(i, 1), u, 0)) Then
n = n + 1
u(n) = v(i, 1)
End If
Next i
ReDim Preserve u(1 To n)
Range("c1").Resize(n, 1).Value = Application.Transpose(u)
End Sub