BrianBeck
asked on
VB6 - Making sure that a file is closed
Dear Gurus
I've been encountering a situation where a text file channel, according to VB, is already open. It occurs about 10% of the time the routine is called. This has given me a rather puzzling problem. How is it that a 'File already open' error can occur at line #112, given that the file channel would have just been closed??
The size of the files saved is rather small, about 1,000 characters. I've carefully checked through the code in my app:
(i) all references to files make use of the 'intfnum = FreeFile' method, ie, no fixed channel assignments
(ii) files are closed prior to the end of each subroutine
I searched EE and found a suggestion to introduce a small delay, hence the loop below. I'm not sure if this has made a difference.
Your help in advance is most appreciated.
Private Function DO_THE_FILE_SAVE(ByVal FilePath As String, ByVal s As String)
'11-oct-07, bring it here
Dim intfnum As Integer, FileChannelNumber As Integer
Dim Result As Long, j As Long
Const procname As String = "DO_THE_FILE_SAVE"
On Error GoTo Err
100 If IsFileAlreadyOpen(FilePath
Close #FileChannelNumber 'if the file happens to still be open from a previous operation, close it
End If
104 For j = 1 To 40000 'delay, typically a few hundred milliseconds, so we can try again
DoEvents
Next
110 intfnum = FreeFile 'a new file handle
112 Open FilePath For Output As #intfnum
114 Print #intfnum, s
116 Close #intfnum
120 Exit Function
Err:
200 MsgBox "ErrCode: " & Erl & vbCrLf & "Error: " & Err.Description 'File already open' error
End Function
Private Function IsFileAlreadyOpen(ByVal FilePath As String, ByVal s As String, ByRef FileChannelNumber As Integer)
'11-oct-07
Dim intfnum As Integer
Const procname As String = "IsFileAlreadyOpen"
On Error GoTo Err
100 intfnum = FreeFile
Open FilePath For Input As #intfnum
Close #intfnum
IsFileAlreadyOpen = 0 'ie, ok
Exit Function
Err:
Select Case Err.number
Case 55 'thanks EE
IsFileAlreadyOpen = -1 'error
FileChannelNumber = intfnum
End Select
End Function
I've been encountering a situation where a text file channel, according to VB, is already open. It occurs about 10% of the time the routine is called. This has given me a rather puzzling problem. How is it that a 'File already open' error can occur at line #112, given that the file channel would have just been closed??
The size of the files saved is rather small, about 1,000 characters. I've carefully checked through the code in my app:
(i) all references to files make use of the 'intfnum = FreeFile' method, ie, no fixed channel assignments
(ii) files are closed prior to the end of each subroutine
I searched EE and found a suggestion to introduce a small delay, hence the loop below. I'm not sure if this has made a difference.
Your help in advance is most appreciated.
Private Function DO_THE_FILE_SAVE(ByVal FilePath As String, ByVal s As String)
'11-oct-07, bring it here
Dim intfnum As Integer, FileChannelNumber As Integer
Dim Result As Long, j As Long
Const procname As String = "DO_THE_FILE_SAVE"
On Error GoTo Err
100 If IsFileAlreadyOpen(FilePath
Close #FileChannelNumber 'if the file happens to still be open from a previous operation, close it
End If
104 For j = 1 To 40000 'delay, typically a few hundred milliseconds, so we can try again
DoEvents
Next
110 intfnum = FreeFile 'a new file handle
112 Open FilePath For Output As #intfnum
114 Print #intfnum, s
116 Close #intfnum
120 Exit Function
Err:
200 MsgBox "ErrCode: " & Erl & vbCrLf & "Error: " & Err.Description 'File already open' error
End Function
Private Function IsFileAlreadyOpen(ByVal FilePath As String, ByVal s As String, ByRef FileChannelNumber As Integer)
'11-oct-07
Dim intfnum As Integer
Const procname As String = "IsFileAlreadyOpen"
On Error GoTo Err
100 intfnum = FreeFile
Open FilePath For Input As #intfnum
Close #intfnum
IsFileAlreadyOpen = 0 'ie, ok
Exit Function
Err:
Select Case Err.number
Case 55 'thanks EE
IsFileAlreadyOpen = -1 'error
FileChannelNumber = intfnum
End Select
End Function
ASKER
Hi jaiganeshsrinivasan:
Thanks, will do. Would be happen to know of an answer to the underlying file open problem?
Thanks, will do. Would be happen to know of an answer to the underlying file open problem?
Private Function DO_THE_FILE_SAVE(ByVal FilePath As String, ByVal s As String)
'11-oct-07, bring it here
Dim intfnum As Integer
Dim Result As Long, j As Long
Const procname As String = "DO_THE_FILE_SAVE"
On Error GoTo Err
100 while (IsFileAlreadyOpen(FilePat
doevents
Sleep(millisecs) instead ' suggested by jaiganeshsrinivasan
Wend
110 intfnum = FreeFile 'a new file handle
112 Open FilePath For Output As #intfnum
114 Print #intfnum, s
116 Close #intfnum
120 Exit Function
Err:
200 MsgBox "ErrCode: " & Erl & vbCrLf & "Error: " & Err.Description 'File already open' error
End Function
Private Function IsFileAlreadyOpen(ByVal FilePath As String)
'11-oct-07
Dim intfnum As Integer
Const procname As String = "IsFileAlreadyOpen"
On Error GoTo Err
100 intfnum = FreeFile
Open FilePath For Input As #intfnum
Close #intfnum
IsFileAlreadyOpen = 0 'ie, ok
Exit Function
Err:
Select Case Err.number
Case 55 'thanks EE
IsFileAlreadyOpen = -1 'error
End Select
End Function
'11-oct-07, bring it here
Dim intfnum As Integer
Dim Result As Long, j As Long
Const procname As String = "DO_THE_FILE_SAVE"
On Error GoTo Err
100 while (IsFileAlreadyOpen(FilePat
doevents
Sleep(millisecs) instead ' suggested by jaiganeshsrinivasan
Wend
110 intfnum = FreeFile 'a new file handle
112 Open FilePath For Output As #intfnum
114 Print #intfnum, s
116 Close #intfnum
120 Exit Function
Err:
200 MsgBox "ErrCode: " & Erl & vbCrLf & "Error: " & Err.Description 'File already open' error
End Function
Private Function IsFileAlreadyOpen(ByVal FilePath As String)
'11-oct-07
Dim intfnum As Integer
Const procname As String = "IsFileAlreadyOpen"
On Error GoTo Err
100 intfnum = FreeFile
Open FilePath For Input As #intfnum
Close #intfnum
IsFileAlreadyOpen = 0 'ie, ok
Exit Function
Err:
Select Case Err.number
Case 55 'thanks EE
IsFileAlreadyOpen = -1 'error
End Select
End Function
ASKER
Hi EDDYKT:
Thanks, but from what I've seen 'sleeping' or 'waiting' doesnt seem to solve the underlying problem.
Is there some way in which I can brute force delete the existing file (I've already saved the new contents in a string, so once the file is deleted, I'd simply create a new text file with the same name as the original one).
In other words, is there a way to bypass VB's built in open file check, and simply request Windows to delete the file? I realise that this may be unorthodox, but can it be done?
Brian
Thanks, but from what I've seen 'sleeping' or 'waiting' doesnt seem to solve the underlying problem.
Is there some way in which I can brute force delete the existing file (I've already saved the new contents in a string, so once the file is deleted, I'd simply create a new text file with the same name as the original one).
In other words, is there a way to bypass VB's built in open file check, and simply request Windows to delete the file? I realise that this may be unorthodox, but can it be done?
Brian
ASKER CERTIFIED SOLUTION
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ASKER
Hi EddyKT
Thanks for your suggestions, though as I need an automated, reliable approach, the registry method seems promising. I'm unsure as to why the file remains open.
Is there a limit to the number of characters in can have in a string? Can the string have CRLF delimeters?
Thanks for your suggestions, though as I need an automated, reliable approach, the registry method seems promising. I'm unsure as to why the file remains open.
Is there a limit to the number of characters in can have in a string? Can the string have CRLF delimeters?
if you use string value in registry 8192 is max number of char (if i remember correctly)
if you have more than the above number, use expanable string
if you have more than the above number, use expanable string
use
Sleep(millisecs) instead
and call DoEvents
Sleep(your integer value)
DoEvents