If towrite Then
      'Zeile danach schreiben (falls bedingung erfüllt und Zeile vorhanden)
      Print #ak, zeilep
      Print #ak, ""
   End If

Private Function CheckLines2(ByVal infile As String, ByVal outfile As String, _
               ByVal PrüfSpalte As Integer) As Boolean
 
On Error GoTo fehler
Dim lines() As String, ak%, i%, k%, fieldsv$(), fieldsp$()
 
'Zeilen lesen
If Not ReadLines(infile, lines) Then CheckLines2 = False: Exit Function
 
ak = FreeFile
Open outfile For Output As #ak
For i = 1 To UBound(lines)
   fieldsv = Split(lines(i - 1), ",")
   fieldsp = Split(lines(i), ",")
 
   If CInt(Trim(fieldsv(PrüfSpalte))) <> _
       CInt(Trim(fieldsp(PrüfSpalte))) Then
       Print #ak, lines(i - 1)
       Print #ak, lines(i)
       If i < UBound(lines) Then
          Print #ak, lines(i + 1)
          Print #ak, ""
       End If
   End If
Next i
Close #ak
CheckLines2 = True
Exit Function
 
fehler:
Close #ak
CheckLines2 = False
End Function
 
 
Private Function ReadLines _
   (ByVal infile As String, ByRef lines() As String) As Boolean
 
On Error GoTo fehler
ReDim lines(100)
Dim z As Integer: z = -1
Dim ik As Integer
ik = FreeFile
Open infile For Input As #ik
While Not EOF(ik)
   z = z + 1
   If UBound(lines) < z Then
      ReDim Preserve lines(z + 100)
   End If
   Line Input #ik, lines(z)
Wend
ReDim Preserve lines(z)
Close #ik
ReadLines = True
Exit Function
 
fehler:
ReadLines = False
End Function