In my program everything is working except when you reach Z it counts up to the characters instead of counting back from the start at A.
EDIT: Question is now solved. I had to convert the ascii value to alphabetical, use modulo on the alphabetical, then convert back to ascii. I used modulo on ascii right away and so it wasn't working before, but now it is.
Also, my question has nothing to do with the "array index" question that this was marked as duplicate of.