如何在外部的txt的第二行输入值?

实现不了吗？

55555555555555 是不是想让我自己回完啊？

关于调用 看你读取文件了

帮你找到一个获取文本行数的函数
如果要再任意行插入估计还要利用到其他API函数了!
Const WM_USER = &H400
Const EM_GETLINECOUNT = WM_USER + 10

#If Win32 Then

Private Declare Function SendMessage Lib "user32" _
Alias "SendMessageA" _
(ByVal hWnd As Long, _
ByVal wMsg As Long, _
ByVal wParam As Integer, _
lParam As Any) As Long
#Else

Private Declare Function SendMessage Lib "user" _
(ByVal hWnd As Integer, _
ByVal wMsg As Integer, _
ByVal wParam As Integer, _
lParam As Any) As Long
#End If

Function TextLineCount(txtObj As TextBox) As Long
If txtObj.MultiLine = True Then
TextLineCount = SendMessage(txtObj.hWnd, EM_GETLINECOUNT, 0, 0&)
Else
TextLineCount = 1
End If
End Function

如果out5.txt是已存在的文件，用output就会把第一行覆盖!
用append则只能在最后添加
对于顺序文件，我看你只能读出文件所有内容，然后修改第二行(你想改的行数)，再写入