Open Statement

打开一个数据通道。

Open pathname For mode [Access io] [locking] As [#]filenum [Len=recLen]

pathname: Path and name of the file to open. If you try to read a file that does not exist (Access = Read), an error message appears. If you try to write to a file that does not exist (Access = Write), a new file is created.

mode: Keyword that specifies the file mode. Valid values: Append (append to sequential file), Binary (data can be accessed by bytes using Get and Put), Input (opens data channel for reading), Output (opens data channel for writing), and Random (edits relative files).

io: Keyword that defines the access type. Valid values: Read (read-only), Write (write-only), Read Write (both).

locking: Keyword that defines the security status of a file after opening. Valid values: Shared (file may be opened by other applications), Lock Read (file is protected against reading), Lock Write (file is protected against writing), Lock Read Write (denies file access).

filenum: Any integer expression from 0 to 511 to indicate the number of a free data channel. You can then pass commands through the data channel to access the file. The file number must be determined by the FreeFile function immediately before the Open statement.

recLen: For Random access files, set the length of the records.

您只能修改通过 Open 语句打开的文件的内容。如果您尝试打开一个已经打开的文件，则会显示一个错误信息。

Sub ExampleWorkWithAFile
Dim iNumber As Integer
Dim sLine As String
Dim aFile As String
Dim sMsg As String
    aFile = "c:\data.txt"
    iNumber = Freefile
    Open aFile For Output As #iNumber
    Print #iNumber, "This is a line of text"
    Print #iNumber, "This is another line of text"
    Close #iNumber
    iNumber = Freefile
    Open aFile For Input As iNumber
    While Not eof(iNumber)
        Line Input #iNumber, sLine
        If sLine <>"" Then
            sMsg = sMsg & sLine & chr(13)
        End If
    Wend
    Close #iNumber
    MsgBox sMsg
End Sub