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Accessing Global Variables in VBA (Excel)

Posted by: admin May 14, 2020 Leave a comment

Questions:

I’ve never used global variables in VBA, but I understand global variables are instantiated outside of function/sub declarations?

I have a global (public) variable declared at the top of a module which is then given a value of 0 by a subroutine within the same module.

Option Explicit
Public NumNodes As Integer

Sub Inst_Glob_Vars()
NumNodes = 0
End Sub

This subroutine is called whenever the workbook is opened (sub is called in the “ThisWorkbook” object) which will also instantiate the global variable and set the 0 value.

Option Explicit

Private Sub Workbook_Open()
Call Inst_Glob_Vars
End Sub

I have a button in the excel sheet which, when clicked, will increment this global variable. The definition for this button is in the Sheet1 object.

Private Sub CommandButton2_Click()
'NumNodes = NumNodes + 1
Debug.Print "NumNodes = " & NumNodes 'Debug
End Sub

Do I need to declare the global/public variables in every module/object the variable is used? Every time I click the button, the variable is not incrementing but giving a Null/Blank value when debugging. I am for sure not declaring my global variable correctly but not sure where I’m making mistakes.

Update: Here is the updated command button sub. If I comment out second sub call (Node_Button_Duplication), everything works fine. Chances are it might be that sub which is causing problems…

Private Sub CommandButton2_Click()
Call Channel_Selection_Duplication
Call Node_Button_Duplication
NumNodes = NumNodes + 1
Debug.Print "NumNodes = " & NumNodes 'Debug
End Sub

Both Channel_Selection_Duplication and Node_Button_Duplication are both defined in the same seperate module:

Option Explicit

Public Sub Channel_Selection_Duplication()
'
' Description: Macro which duplicates the 'Channel Usage Selection' columns at a specific cell reference

    Range("Q8:S8").Select
    With Selection
        .HorizontalAlignment = xlCenter
        .VerticalAlignment = xlBottom
        .WrapText = False
        .Orientation = 0
        .AddIndent = False
        .IndentLevel = 0
        .ShrinkToFit = False
        .ReadingOrder = xlContext
        .MergeCells = False
    End With
    Selection.Merge
    Range("Q8:S8").Select
    ActiveCell.FormulaR1C1 = "Channel Usage Selection"
    Range("Q8:S52").Select
    Range("Q52").Activate
    Selection.Borders(xlDiagonalDown).LineStyle = xlNone
    Selection.Borders(xlDiagonalUp).LineStyle = xlNone
    With Selection.Borders(xlEdgeLeft)
        .LineStyle = xlContinuous
        .Weight = xlThin
        .ColorIndex = xlAutomatic
    End With
    With Selection.Borders(xlEdgeTop)
        .LineStyle = xlContinuous
        .Weight = xlThin
        .ColorIndex = xlAutomatic
    End With
    With Selection.Borders(xlEdgeBottom)
        .LineStyle = xlContinuous
        .Weight = xlThin
        .ColorIndex = xlAutomatic
    End With
    With Selection.Borders(xlEdgeRight)
        .LineStyle = xlContinuous
        .Weight = xlThin
        .ColorIndex = xlAutomatic
    End With
    With Selection.Borders(xlInsideVertical)
        .LineStyle = xlContinuous
        .Weight = xlThin
        .ColorIndex = xlAutomatic
    End With
    With Selection.Borders(xlInsideHorizontal)
        .LineStyle = xlContinuous
        .Weight = xlThin
        .ColorIndex = xlAutomatic
    End With
    Range("Q8:S8").Select
    Selection.Interior.ColorIndex = 36

'NumNodes = NumNodes + 1
'Debug.Print NumNodes
End Sub

Public Sub Node_Button_Duplication()

    ActiveSheet.Shapes("CommandButton1").Select
    Selection.Copy
    Range("Q5").Select
    ActiveSheet.Paste
    Selection.ShapeRange.IncrementTop -14.25
End Sub
How to&Answers:

Paste this in a module

Option Explicit

Public myVar As Long

Paste this in the command button click event in sheet1

Option Explicit

Private Sub CommandButton1_Click()
    myVar = myVar + 1
    MsgBox myVar
End Sub

Now try it.

Also you don’t need to set the value to 0 in Workbook_Open event 🙂 It takes the value 0 by default when you open the workbook.

FOLLOWUP

I have a feeling copying and pasting a control element in the spreadsheet somehow resets the variable. I’m currently trying to find a solution… – user1373525 6 mins ago

Yes 🙂 Adding the button recompiles the VBA code and hence the global variables get reset. Use a Temp Sheet to hold the variables. You could also use registry to store that information 🙂 – Siddharth Rout just now

This behaviour is only observed if you click the button twice but not when you execute it in one go. For example

Private Sub CommandButton2_Click()
    NumNodes = NumNodes + 1
    MsgBox NumNodes, vbInformation, "1"

    Node_Button_Duplication

    NumNodes = NumNodes + 1
    MsgBox NumNodes, vbInformation, "2"

    Node_Button_Duplication

    NumNodes = NumNodes + 1
    MsgBox NumNodes, vbInformation, "3"
End Sub

In such a case it will always increment the value. However, the next time you click on the button, you will notice that the variable has been reset.