Question mark in spreadsheet causes problems in Excel VBA - excel

Question

When I compare the value of a cell that contains ? to a variable, it always returns true. Is there any way I can prevent this? Here is my current code:
'Option Explicit
Dim hws As Worksheet
Set hws = ActiveSheet
Dim rng As Range, rng2 As Range
Dim letters(2, 2)
alpha = Range("CipherTable").Value
For x = 1 To 7
For y = 1 To 7
If alpha(x, y) = rng.Cells(i, j + 1).Value Then
letters(2, 1) = x
letters(2, 2) = y
End If
Next y
Next x
alpha, by the way, looks like this:
A B C D E F G
H I J K L M N
O P Q R S T U
V W X Y Z 1 2
3 4 5 6 7 8 9
0 ; : ' " . ,
( ) _ - + ? !
This always returns A, which is in alpha(1,1). Come to think of it, since they each go to seven, I don't know why it don't come back with !. How can I get around this and make it return true only when it actually matches?

Answer 1

As far as I understand you want to create a substitution algorithm. If there is no specific reason to use a two dimensional cipher table I would rather use a one dimensional approach like the following:
Function Cipher(Argument As String) As String
Dim Model As String
Dim Subst As String
Dim Idx As Integer
Dim MyPos As Integer
Cipher = ""
' note double quotation mark within string
Model = "ABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890;:'"".,()_-+?!"
Subst = "ABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890;:'"".,()_-+?!"
For Idx = 1 To Len(Argument)
' get position from Model
MyPos = InStr(1, Model, UCase(Mid(Argument, Idx, 1)))
' return character from substitution pattern
If MyPos <> 0 Then Cipher = Cipher & Mid(Subst, MyPos, 1)
Next Idx
End Function
calling this function with
Sub Test()
Debug.Print Cipher("The quick brown (?) fox 123 +-")
End Sub
results in THEQUICKBROWN(?)FOX123+- (because we don't allow blanks in Model or Subst)
Now change Subst to
Subst = "!?+-_)(,.""':;0987654321ZYXWVUTSRQPONMLKJIHGFEDCBA"
result is 4,_73.+'?6910GBF)9ZWVUCD
if you feed the above into the cipher function, you end up again with THEQUICKBROWN(?)FOX123+- as you would expect from a symetrical substitution.

Answer 2

I tried the following, and got the expected result (it was able to find the question mark):
(1) Created CipherTable range in worksheet, as above;
(2) Created a function QM similar to code above;
(3) Entered a formula in the style of =QM(cell-ref).
It worked fine. Function QM:
Public Function QM(theChar)
Dim CipherTable
Dim x As Integer
Dim y As Integer
CipherTable = Range("CipherTable").Value
For x = 1 To 7
For y = 1 To 7
If CipherTable(x, y) = theChar Then
QM = "X" & x & "Y" & y
Exit Function
End If
Next y
Next x
QM = ""
End Function
====
I also tried something more direct, and got the response expected:
Public Sub QM2()
Dim questMark As Range
Dim someChar As String
Set questMark = Range("CipherTable").Cells(7, 6)
someChar = "A"
Debug.Print questMark = someChar
End Sub