[RESOLVED] Overlap through array?

[Disyne]

Hi.

I have a string array with the contents of the alphabet:
MyString(0) = "a"
MyString(1) = "b"
etc


I have a function that takes a letter and an integer and returns the letter.
For example:
GetAlpha("c",2) would return "e" because 2 placements ahead of c is e.

For the function above if I get a number that exceeds the upper bound I use the mod operator to 'overlap?' again. This works fine from what I have tested.

But the problem is if I use a negative number that exceeds the lower bound, how do I overlap from the end?
Like if I do GetAlpha("a",-2) if would return "y".

[Merri]

You simply add the count, ie:

NewIndex = (Count + OldIndex - 2) Mod Count

[Merri]

In the other hand: why have an array?

Option Explicit

Public Function GetAlpha(ByRef Character As String, ByVal Jump As Integer) As String
    Dim lngChar As Long
    ' get the character code
    lngChar = AscW(Character) - 97
    ' must be a - z
    If lngChar >= 0 And lngChar <= 25 Then
        ' validate jump
        If Jump >= 0 Then
            Jump = Jump Mod 26
        Else
            Jump = -(-Jump Mod 26)
        End If
        ' now generate the character
        GetAlpha = ChrW$((26 + lngChar + Jump) Mod 26 + 97)
    End If
End Function

Private Sub Form_Load()
    Debug.Print GetAlpha("a", 28)
    Debug.Print GetAlpha("a", -28)
End Sub