VBA Finding the next column based on an input value - excel

Question

In a program that I'm trying to write now I take two columns of numbers and perform calculations on them. I don't know where these two columns are located until the user tells me (they input the column value in a cell in the workbook that my code is located in).
For example, if the user inputted "A" and "B" as the columns where all the information is in I can perform calculations based on those values. Likewise if they wanted to analyze another worksheet (or workbook) and the columns are in "F" and "G" they could input those. The problem is that I'm asking the user to input those two columns as well as four others (the last four are the result columns). I did this in hopes that I would be able to make this flexible, but now inflexibility is acceptable.
My question is, if I'm given a value of where some information will be (let's say "F") how can I figure out what the column will be after or before that inputted value. So if I'm only given "F" I'll be able to create a variable to hold the "G" column.
Below are examples of how the variables worked before I needed to do this new problem:
Dim first_Column As String
Dim second_Column As String
Dim third_Column As String
first_Column = Range("B2").Text
second_Column = Range("B3").Text
third_Column = Range("B4").Text
Here the cells B2 - B4 are where the user inputs the values. Generally I want to be able to not have the B3 and B4 anymore. I feel like the Offset(0,1) might be able to help somehow but so far I've been unable to implement it correctly.
Thank you,
Jesse Smothermon

Answer 1

Here are two functions that will help you dealing with columns > "Z". They convert the textual form of a column to a column index (as a Long value) and vice versa:
Function ColTextToInt(ByVal col As String) As Long
Dim c1 As String, c2 As String
col = UCase(col) 'Make sure we are dealing with "A", not with "a"
If Len(col) = 1 Then 'if "A" to "Z" is given, there is just one letter to decode
ColTextToInt = Asc(col) - Asc("A") + 1
ElseIf Len(col) = 2 Then
c1 = Left(col, 1) ' two letter columns: split to left and right letter
c2 = Right(col, 1)
' calculate the column indexes from both letters
ColTextToInt = (Asc(c1) - Asc("A") + 1) * 26 + (Asc(c2) - Asc("A") + 1)
Else
ColTextToInt = 0
End If
End Function
Function ColIntToText(ByVal col As Long) As String
Dim i1 As Long, i2 As Long
i1 = (col - 1) \ 26 ' col - 1 =i1*26+i2 : this calculates i1 and i2 from col
i2 = (col - 1) Mod 26
ColIntToText = Chr(Asc("A") + i2) ' if i1 is 0, this is the column from "A" to "Z"
If i1 > 0 Then 'in this case, i1 represents the first letter of the two-letter columns
ColIntToText = Chr(Asc("A") + i1 - 1) & ColIntToText ' add the first letter to the result
End If
End Function
Now your problem can be solved easily, for example
newColumn = ColIntToText(ColTextToInt(oldColumn)+1)
EDITED accordingly to the remark of mwolfe02:
Of course, if you are not interested in the column names, but just want to get a range object of a specific cell in a given row right beneath a column given by the user, this code is "overkill". In this case, a simple
Dim r as Range
Dim row as long, oldColumn as String
' ... init row and oldColumn here ...
Set r = mysheet.Range(oldColumn & row).Offset(0,1)
' now use r to manipulate the cell right to the original cell
will do it.

Answer 2

You were on the right track with Offset. Here is a test function that shows a couple different approaches to take with it:
Sub test()
Dim first_Column As String
Dim second_Column As String
Dim third_Column As String
Dim r As Range
first_Column = Range("B2").Text
second_Column = Range("B2").Offset(1, 0).Text
third_Column = Range("B2").Offset(2, 0).Text
Debug.Print first_Column, second_Column, third_Column
Set r = Range("B2")
first_Column = r.Text
Set r = r.Offset(1, 0)
second_Column = r.Text
Set r = r.Offset(1, 0)
third_Column = r.Text
Debug.Print first_Column, second_Column, third_Column
End Sub
UPDATE: After re-reading your question I realize you were trying to do offsets based on a user-entered column letter. #rskar's answer will shift the column letter, but it will be a lot easier to work with the column number in code. For example:
Sub test()
Dim first_Col As Integer, second_Col As Integer
first_Col = Cells(, Range("B2").Text).Column
second_Col = first_Col + 1
Cells.Columns(first_Col).Font.Bold = True
Cells.Columns(second_Col).Font.Italic = True
End Sub

Answer 3

There are a few syntactical problems with #rskar's answer. However, it was helpful in producing a function that grabs a column "letter", based on an input column "letter" and a desired offset to the right:
Public Function GetNextCol(TheCol As String, OffsetRight As Integer) As String
Dim TempCol1 As String
Dim TempCol2 As String
TempCol1 = Range(TheCol & "1").Address
TempCol2 = Range(TempCol1).Offset(0, OffsetRight).Address(0, 0, xlA1)
GetNextCol = Left(TempCol2, Len(TempCol2) - 1)
End Function

Answer 4

In light of the comments of others (and they all raised valid points), here is a much better solution to the problem, using Offset and Address:
Dim first_Column As String
Dim second_Column As String
Dim p As Integer
first_Column = Range("B2").Text
second_Column = _
Range(first_Column + ":" + first_Column).Offset(0, 1).Address(0, 0, xlA1)
p = InStr(second_Column, ":")
second_Column = Left(second_Column, p - 1)
The above should work for any valid column name, "Z" and "AA" etc. included.

Answer 5

Make use of the Asc() and Chr() functions in VBA, like so:
Dim first_Column As String
Dim second_Column As String
first_Column = Range("B2").Text
second_Column = Chr(Asc(first_Column) + 1)
The Asc(s) function returns the ASCII code (in integer, usually between 0 and 255) of the first character of a string "s".
The Chr(c) function returns a string containing the character which corresponds to the given code "c".
Upper case letters (A thru Z) are ASCII codes 65 thru 90. Just google ASCII for more detail.
NOTE: The above code will be fine so long as the first_Column is between "A" and "Y"; for columns "AA" etc., it will take a little more work, but Asc() and Chr() will still be the ticket to coding for that.