在vb中开txt file 把内容写入 listbox中， 在listbox中选取内容，按下button写入另一个txtfile中

如果list需要多项选择的话，应该是这样：
Private Sub Command1_Click()
Dim n As Integer
Dim s As String
n = FreeFile
Open "d:\1.TXT" For Input As n
Do Until EOF(n)
Line Input #n, s
List1.AddItem s
Loop
Close
End Sub

Private Sub Command2_Click()
Dim n As Integer
n = FreeFile
Open "d:\2.TXT" For Append As n
For I = 0 To List1.ListCount - 1'写入选择的内容
If List1.Selected(I) Then
Print #n, List1.List(I)
End If
Next I
Close
End Sub

Private Sub Command1_Click()
'读入List1
Dim n As Integer
Dim s As String
n = FreeFile
Open "e:\1.TXT" For Input As n
Do Until EOF(n)
Line Input #n, s
List1.AddItem s
Loop
Close
End Sub

Private Sub Command2_Click()
'写入文件
If List1.Text <> "" Then
Dim n As Integer: n = FreeFile
Open "e:\2.TXT" For Append As n
Print #n, List1.Text
Close
End If
End Sub