Remove duplicates from array using VBA

Question

Assume I have a block of data in Excel 2010, 100 rows by 3 columns.

Column C contains some duplicates, say it starts off as

1, 1, 1, 2, 3, 4,

Answer 1

Dictionaries have a max of 255 items, so if you have more values you need to use a Collection. Unfortunately, the Collection object does not have a .Contains(a) or .Exists(a) method, but this function handles (fakes it) it nicely by using the Error numbers:

CORRECTION: Dictionaries do not have such a limit (thanks Zairja). I may have been using an Integer to iterate through my Dictionary. In any event, this function allows you to check Collections for item existence, so I'll leave it here if it's useful to anyone:

CollContainsItem(col As Collection, val As Variant) As Boolean

Dim itm As Variant
On Error Resume Next

    itm = col.Item(val)
    CollContainsItem = Not (Err.Number = 5 Or Err.Number = 9)

On Error GoTo 0

End Function

So if you do need a Collection, you could likely just replace

dict.Exists(strVal)

with

CollContainsItem(coll, strVal)

and replace

Set dict = CreateObject("Scripting.Dictionary")

with

Set coll = CreateObject("Scripting.Collection")

And use the rest of Zairja's code. (I didn't actually try it but it should be close)