Question

I want to return true if some strings = ‘XXXXX’

Where every X is a number 0 through 9

I know there must be a dozen ways to do this but I would like to know the best way.

Answer 1

If you want the simplest way, you can go with this:

Function MyFunction(myString As String) As Boolean
    MyFunction = ((Len(myString) = 5) And (IsNumeric(myString)))
End Function

If you want the more efficient way, you’d have to run some tests for the different methods people suggested.

Edit: The previous solution doesn’t work well (see the first 2 comments) but I’m letting it there since it’s what has been accepted. Here is what I would do :

Function MyFunction(myString As String) As Boolean
    Dim myDouble As Double
    Dim myLong As Long
    myDouble = Val(myString)
    myLong = Int(myDouble / 10000)
    MyFunction = ((Len(myString) = 5) And (myLong > 0) And (myLong < 10))
End Function

There is no error “protection” in that function, so if you try to check a too large number like 22222222222222, it will not work.