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Lock File Method

The Lock File method controls access to an open file. It does not return a value.

Format

Lock [#]filenumber[, [start] [To end]]

The following table describes the arguments that you can use with this method.

Specifying the Start Argument and End Argument

The Lock File method locks the file according to the following modes:

• Binary mode. The start argument and the end argument identify byte offsets.
• Random mode. The start argument and the end argument identify record numbers:
  • If you include the start but not the end, then it locks only the record or byte that the start argument identifies.
  • If you include the end but not the start, then it locks records or bytes from the record number or offset 1 to the end.
• Input mode, output mode, or append mode. It locks the entire file. It ignores the start argument and the end argument.

Removing Locks

You must use the Lock File method and the Unlock File method in pairs to remove a lock, and the arguments that you use with these methods must be identical. For more information, see Unlock File Method.

You must configure Siebel VB to remove a lock on an open file before it closes the file. If you do not do this, then unpredictable results might occur.

Example

In the following example, if the file is already in use, then this code locks the file that other users on a network share. The CreateFile subroutine creates the file that the main subroutine uses:

(general) (declarations)
Option Explicit
Declare Sub CreateFile

Sub CreateFile
   ' Put the letters A-J into the file
   Dim x as Integer
   Open "c:\temp001" for Output as #1
   For x = 1 to 10
      Write #1, Chr(x + 64)
   Next x
   Close #1
End Sub

Sub Button_Click
   Dim btngrp, icongrp
   Dim defgrp
   Dim answer
   Dim noaccess as Integer
   Dim msgabort
   Dim msgstop as Integer
   Dim acctname as String
   noaccess = 70
   msgstop = 16
   Call CreateFile
   On Error Resume Next
   btngrp = 1
   icongrp = 64
   defgrp = 0
   answer = 1
   If answer = 1 then
      Open "c:\temp001" for Input as #1
      If Err = noaccess then
            'File Locked -Aborted
      Else
         Lock #1
         Line Input #1, acctname
         Unlock #1
      End If
      Close #1
   End If
      Kill "C:\TEMP001"
End Sub