Function to count distinct values in a column range

Question

I am attempting to create a function in VBA that, when given a range of values, will return a Count Distinct of those values. For example:

| Column A | |-----

Answer 1

Way late to the party, but I thought I would put in another VBA option that does not require adding a reference.

In addition this touches on a neat function of excel VBA that I wish I had learn much earlier.

My solution to this uses the Collection object in order to find distinct values.

Option Explicit
'^ As SeanC said, adding Option Explicit is a great way to prevent writing errors when starting out.
Public Function CountDistinct(r As Range) As Long
'' DIM = declare in memory

Dim col As Collection
Dim arr As Variant
Dim x As Long
Dim y As Long

Set col = New Collection
'' setting a Variant = Range will fill the Variant with a 2 dimensional array of the values of the range!
arr = r
'' skip the errors that are raised
On Error Resume Next
'' loop over all of the elements.
'' UBound is a built in VBA Function that gives you the largest value of an array.
    For x = 1 To UBound(arr, 1)
        For y = 1 To UBound(arr, 2)
            '' try to add the value in arr to the collection
            col.Add 0, CStr(arr(x, y))

            '' every time the collection runs into a value it has already added,
            '' it will raise an error.
            'uncomment the below to see why we are turning off errors
            'Debug.Print Err.Number, Err.Description

        Next
    Next
'' turn errors back on.
On Error GoTo 0
''set the function name to the value you want the formula to return
CountDistinct = col.Count
'' The next parts should be handled by VBA automatically but it is good practise to explicitly clean up.
Set col = Nothing
Set arr = Nothing
Set r = Nothing
End Function

I hope this helps someone down the line.