Memory leak when opening Excel - resulting in a crash - excel

Question

I have a matrix with i.e dimensions 300x300 (x & y,size vary from project to project).
The names/numbers of the individual rows are transposed to the columns.
The matrix is divided diagonally, and I use it to tag relations between different "systems".
The tag have to be a unique number. See image:
I do not want duplicated relations, so I just want to use the white cells to add the tag.
(The black ones are there to show that the system cant have a relation with itself.)
I have tried to make a range, that I apply a Validation to later which shows me the next number in line for the tag:
Public MatrixRange as Range
Private Sub Worksheet_Activate()
Dim n As Integer
Dim NextRange As Range
Dim OldRange As Range
Dim LastRow As Long
With shMatrix
LastRow = .Range("A" & .Rows.Count).End(xlUp).row
Set MatrixRange = .Range("C11")
If LastRow <= 1 Then Exit Sub
For n = 2 To .Range(.Range("A9").Offset(1, 0).Address, "A" & LastRow).Rows.Count
Set OldRange = MatrixRange
Set NextRange = .Range(.Range("B9").Offset(n, 1), .Range("B9").Offset(n, -1 + n))
Set MatrixRange = Union(OldRange, NextRange)
Next n
End With
End Sub
This code give me the correct range that I want, but it sometimes hogs a whole lot of memory when I open the workbook or try to save. The RAM just goes up and up when I start it, before the workbook just crashes without any error message.
Rewriting the code to select the whole matrix, not just the one half, seems to fix the issue.
My question is this: is it possible to rewrite the code so I get the correct range, with a different method or are there any flaws in my code that will create a memory leak?
I call the above sub also when applying the Validation, if MatrixRange is not created:
Private Sub Worksheet_SelectionChange(ByVal Target As Range)
Dim ValMax As Integer
If MatrixRange Is Nothing Then
Call CreateMatrixRange
End If
ValMax = Application.WorksheetFunction.Max(MatrixRange)
With MatrixRange.Validation
.Delete
.Add Type:=xlValidateWholeNumber, AlertStyle:=xlValidAlertStop, _
Operator:=xlEqual, Formula1:=ValMax + 1
.IgnoreBlank = True
.InCellDropdown = False
.InputTitle = "Next number"
.ErrorTitle = "Error"
.InputMessage = ValMax + 1
.ErrorMessage = "Next number is: " & ValMax + 1
.ShowInput = True
.ShowError = True
End With
End Sub
Thank you for your answers!

Answer 1

Try the following:
Option Explicit
Private prMatrix As Range
'* plLastRow is used to check if the matrix range changes after it had been set
Private plLastRow As Long
Private Function GetMatrixRange() As Range
Dim lStartCol As Long: lStartCol = 3
Dim lStartRow As Long: lStartRow = 11
Dim lLastRow As Long
Dim i As Long
With shMatrix
lLastRow = .Cells(Rows.Count, "A").End(xlUp).Row
If lLastRow < lStartRow Then lLastRow = lStartRow
If prMatrix Is Nothing Or lLastRow <> plLastRow Then
plLastRow = lLastRow
Set prMatrix = .Cells(lStartRow, lStartCol)
'* Row Number -> Number of Columns mapping
'* Row 11 -> 1 column
'* Row 12 -> 2 columns
'* Row 13 -> 3 columns , ...etc
'* Therefore, Number Of Columns = Row Number - lStartRow + 1
For i = lStartRow + 1 To lLastRow
Set prMatrix = Union(prMatrix, .Cells(i, lStartCol).Resize(1, i - lStartRow + 1))
Next i
End If
End With
Set GetMatrixRange = prMatrix
End Function
Private Function GetNextValue() As Long
GetNextValue = WorksheetFunction.Max(GetMatrixRange) + 1
End Function
'Private Sub SetValidation()
' Dim lNextValue As Long
' lNextValue = GetNextValue
'
' With GetMatrixRange.Validation
' .Delete
' .Add Type:=xlValidateWholeNumber, _
' AlertStyle:=xlValidAlertStop, _
' Operator:=xlEqual, _
' Formula1:=lNextValue
' .IgnoreBlank = True
' .InCellDropdown = False
' .InputTitle = "Next number"
' .ErrorTitle = "Error"
' .InputMessage = lNextValue
' .ErrorMessage = "Next number is: " & lNextValue
' .ShowInput = True
' .ShowError = True
' End With
'End Sub
'
'Private Sub Worksheet_SelectionChange(ByVal Target As Range)
' SetValidation
'End Sub
Private Sub Worksheet_BeforeDoubleClick(ByVal Target As Range, Cancel As Boolean)
On Error GoTo ErrorHandler
Application.EnableEvents = False
If Not Intersect(Target, GetMatrixRange) Is Nothing Then
If Target = Empty Then Target.Value = GetNextValue
Cancel = True
End If
ErrorHandler:
Application.EnableEvents = True
End Sub
Private Sub Worksheet_Change(ByVal Target As Range)
On Error GoTo ErrorHandler
Application.EnableEvents = False
Dim rWatched As Range: Set rWatched = Intersect(Target, GetMatrixRange)
Dim lNextValue As Long
Dim lEnteredValue As Long
If Not rWatched Is Nothing Then
Target.Select
If rWatched.Cells.Count > 1 Then
rWatched.ClearContents
MsgBox "You cannot change more than 1 matrix cell at a time"
ElseIf Not IsNumeric(rWatched.Value) Then
rWatched.ClearContents
MsgBox "Only numeric values allowed"
Else
If rWatched.Value <> Empty Then
lEnteredValue = rWatched.Value
rWatched.ClearContents
lNextValue = GetNextValue
If lEnteredValue <> lNextValue Then
If MsgBox("The next allowed value is: " & lNextValue & ". Do you want to accept it?", vbYesNo) = vbYes Then
rWatched.Value = lNextValue
End If
Else
rWatched.Value = lEnteredValue
End If
End If
End If
End If
ErrorHandler:
Application.EnableEvents = True
End Sub
I replaced the validation code with double-click and change event handlers. Feel free to remove these handlers and uncomment the validation and selection change code if you need to.
This code will do the following:
If you change any cell in the matrix, it will validate it and give
you the choice to accept the allowed value. Otherwise, it will delete
what you had entered.
If you double-click a cell in the matrix, it will be populated with the next value