How to pass in a Range parameter for VLookup function?

Question

I have the two functions below in VBA. The abb00 works fine but the abb11 does not.

My question is how to pass in a Range variable as a parameter for VLookup function?

Function abb00() 'demo func
    abb00 = Application.WorksheetFunction.VLookup("a", _ 
        Worksheets("SheetCache").Range("A:B"), 2, False)
End Function

Function abb11() 'demo func
    rangeVar = Worksheets("SheetCache").Range("A:B")
    abb11 = Application.WorksheetFunction.VLookup("a", rangeVar, 2, False)
End Function

Answer 1

You can do this in two ways

Fixing your Function
Your current Function is not setting a range variable. It will work like this

Function abb11()
    Dim rangeVar as Range
    Set rangeVar = Worksheets("SheetCache").Range("A:B")
    abb11 = Application.WorksheetFunction.VLookup("a", rangeVar, 2, False)
End Function

Passing a Range to your Function
Alternatively you can pass a range to the Function like this

Sub GetRange()
    Dim rangeVar As Range
    Set rangeVar = Worksheets("SheetCache").Range("A:B")
    MsgBox abb2(rangeVar)
End Sub
Function abb2(ByVal rangeVar)
       abb2 = Application.WorksheetFunction.VLookup("a", rangeVar, 2, False)
End Function

Answer 2

To pass a range, you first need to get a reference to a range.

You currently have this:

rangeVar = Worksheets("SheetCache").Range("A:B")

This doesn't get a range; it reads the entire range A:B into a Variant array. If you want to get a range reference, you need to use the Set keyword.

Set rangeVar = Worksheets("SheetCache").Range("A:B")

Ironically this doesn't impact the output of your abb11 function (EDIT: in Excel 2003), because VLookup can be applied to a Variant array as well as to a Range. However, reading two whole columns into an array is rather inefficient, so I would stick to getting a range reference (Set rangeVar = ...). EDIT In Excel 2007/2010, reading two entire columns into a Variant array will probably cause your function to die, because there are a million rows to load as opposed to 65536 in Excel 2003, which is what I was testing.