Question

Looking for the best way to do this in VB6. Typically, I would use this approach…

   ' count spaces
    For i = 1 To Len(text)
        If Mid$(text, i, 1) = " " Then count = count + 1 
    Next

Answer 1

I would use a modified bucket sort:

Dim i as Integer
Dim index As Integer
Dim count as Integer
Dim FoundByAscii(0 To 255) As Boolean
For i = 1 To Len(text)
    index = Asc(Mid$(text, i, 1))
    FoundByAscii(index) = True
Next i
count = 0
For i = 0 To 255
    If FoundByAscii(i) Then
        count = count + 1
    End If
Next i

…and your result is in count. The performance is O(N) – if Mid$ is O(1).

Edit:

Based on your clarification, do this:

   ' count spaces
    Dim asciiToSearchFor As Integer
    asciiToSearchFor = Asc(" ")
    For i = 1 To Len(text)
        If Asc(Mid$(text, i, 1)) = asciiToSearchFor Then count = count + 1 
    Next

As ascii compares have to be faster that string comparison. I’d profile it just in case, but I’m pretty sure.