Option Explicit
Dim myArray() As String
 
Private Sub cmdSave_Click()
Dim j As Integer
Dim i As Integer
Dim iCount As Integer
Dim bFound As Boolean
 
Open App.Path & "\Data.dat" For Input As #1
 
    Do Until EOF(1)
    iCount = iCount + 1
ReDim Preserve myArray(iCount)
Input #1, myArray(iCount - 1)
 
Debug.Print myArray(0)
Debug.Print myArray(1)
 
    Loop
Close #1
'----------------------------------------------------
Open App.Path & "\Data.dat" For Append As #1
 
        For i = 0 To UBound(myArray)
            bFound = False
            For j = 0 To List1.ListCount - 1
                If myArray(i) = List1.List(j) Then
                    bFound = True
                    Exit For
                End If
            Next j
            If bFound = False Then
                ' Zeile wurde in der Liste nicht gefunden also an Textdatei 
                ' anhängen:
                 Print #1, List1.List(j)
            End If
        Next i
Close #1
End Sub