Custom Excel Functions to compare two strings

Excel Comparison.txt

Public Function countDifferences(str1 As String, str2 As String) As Integer
    Dim i As Integer
    If Len(str1) <> Len(str2) Then
        countDifferences = -1
        Exit Function
    End If
    
    countDifferences = 0
    For i = 1 To Len(str1)
        If Mid(str1, i, 1) <> Mid(str2, i, 1) Then
            countDifferences = countDifferences + 1
        End If
    Next i
    
End Function


Public Function findDifferences(str1 As String, str2 As String) As String
    Dim i As Integer
    If Len(str1) <> Len(str2) Then
        findDifferences = "error"
        Exit Function
    End If
    
    findDifferences = ""
    For i = 1 To Len(str1)
        If Mid(str1, i, 1) <> Mid(str2, i, 1) Then
            If Len(findDifferences) > 0 Then
                findDifferences = findDifferences & ","
            End If
            findDifferences = findDifferences & Str(i)
        End If
    Next i
    
End Function