Excel VBA - HOW to get cell formula.txt

Option Explicit

Public Function seekFormula(rowIDX As Integer, colIDX As Integer) As String

    Dim txtstr As String
    
    Dim colnum As String
    Dim colTxt As String
    
    Dim isFOR   As Boolean
    
    Cells(rowIDX, colIDX).Select
    
    txtstr = ActiveCell.FormulaR1C1
    txtstr = ActiveCell.Formula
    
    isFOR = (Left(Trim(txtstr), 1) = "=")
    
'   Debug.Print "first letter = >>>" + Left(Trim(txtstr), 1) + "<<<"
    
    colnum = Asc("A") + colIDX - 1
    
    colTxt = Chr(colnum)
    
    txtstr = colTxt + Str(rowIDX) + " ===  " + txtstr
    
    If Not isFOR Then txtstr = ""

    seekFormula = txtstr
    
End Function


Public Sub showFOR()

    Dim idxR As Integer
    Dim idxC As Integer
    
    Dim linstr As String
    Dim allstr As String
    
    allstr = "" + Chr(13) + Chr(10)
    
    For idxR = 1 To 100
    
        For idxC = 1 To 20
        
            linstr = seekFormula(idxR, idxC)
            
            If Len(linstr) > 0 Then
                
                allstr = allstr + linstr + Chr(13) + Chr(10)
            End If
            
        
        Next idxC
    
        allstr = allstr + Chr(13) + Chr(10)
        
    Next idxR
    
    Open "d:\\xls-formula.txt" For Output As #1
    Write #1, allstr
    Close #1
    
    MsgBox "Alles in Ordnung!!!"

End Sub