I'm working with text files. Actually one file, where I have to copy information to it. I'm using streamReader and streamWriter. But I'm having an error whenver I close the file and try to open it again. I can't open it again to start writing from where I stopped, and if I use the same IO writer in any other sub method, I get a run-time error message saying that file is being used. Is there any way that I can close and open the text file separately at anytime?
Dim ioFile As New StreamWriter(filename, False)
'code
iofile.close()
There is no problem in how many times I read or Write in between , but whenever I close it, can't open it.
Wrap the streamwriter in a using clause, and set AutoFlush to True:
Using ioFile As New StreamWriter(filename, True)
ioFile.AutoFlush = True
'Code
End Using
Related
So I want to do this:
Open file "this.txt"
Write a line to this file (replacing anything else written to this file)
[Other stuff, irrelevant to the file]
Write a line to this file (replacing anything else written to this file)
Close the file
I thought it would be easy, but I was wrong. I tried many ways, but they all failed. Either they wouldn't let me write in an open file, or they would open the file and immediately close it (WriteAllText).
I ended up using FileOpen(), PrintLine() and FileClose() which lets me write in an open file but PrintLine only writes a new line, it doesn't replace everything in the file. Any help? Either with the printline or the whole thing
It is crucial that the file stays open until the very last moment I want it closed, (cause I have another program checking to see when this file is not open/used).
If this is about VB.NET, then you can use File.Open() with mode = FileMode.Truncate. This clears the file on opening. This assumes that the file exists.
You can also use SetLength() to truncate:
Dim f As FileStream
' FileMode.Truncate also works, but the file needs to exist from before
f = File.Open("test.txt", FileMode.OpenOrCreate, FileAccess.Write)
f.SetLength(0) ' truncate to zero size
Dim line As String = "hello2"
Dim w = New StreamWriter(f)
w.WriteLine(line)
w.Flush()
w.Close()
f.Close()
If this is about VB6, check out this question. One solution there is to import and use a native Windows function that does truncation.
In VB.Net OpenTextFileWriter does exactly what you need (docs):
Dim file As System.IO.StreamWriter
file = My.Computer.FileSystem.OpenTextFileWriter("c:\test.txt", False)
file.WriteLine("Here is the first string.")
file.Close()
i have an application that create a txt file and write in it a log.
I create the txt file with the following code:
If System.IO.File.Exists(sFileName) = True Then
System.IO.File.Delete(sFileName)
End If
'System.IO.File.Create(sFileName) '.dispose
Dim objWriter As New System.IO.StreamWriter(sFileName, True)
When i finish to write the log (using objWriter.WriteLine) and close it (objwriter.close and objwriter.dispose), send it by mail and need to delete it.
In order to delete the file i use this code:
For i = 0 To 10
Try
'System.IO.File.Delete(sFileName)
'My.Computer.FileSystem.DeleteFile(sFileName, FileIO.UIOption.OnlyErrorDialogs, FileIO.RecycleOption.DeletePermanently)
My.Computer.FileSystem.DeleteFile(sFileName)
Exit For
Catch ex As Exception
If i = 10 Then
invioMailTest(ex.ToString)
End If
Threading.Thread.Sleep(1000)
End Try
Next
The code works well in local, but when i run it on the server (as administrator) it gives me the following error:
System.IO.IOException: The process cannot access the file 'C:\Log_Eventi\Export log 2016-04-13.txt' because it is being used by another process.
i don't know how to delete it and i'm losing too much time on it....
When you create your file I'm guessing you are using
System.IO.File.Create(sFileName)
You can overcome that problem by using this code:
Using File.Create(sFileName)
End Using
put all code that deals with sFileName within Using.
other solutions:
use Close when you create it
System.IO.File.Create(sFileName).Close()
use filestream
Dim fs As FileStream = File.Create(sFileName)
do your work here
fs.Close()
You mention "send it by mail", so the problem is likely that the attachment is still being held by the server's email system.
I'm sure this is really simple, but has had me stumped for a while!
I need to show the user a text file, with lines being written to it as my program executes. Stuff like "Working on this file - Successful!". Another forum thread has helped me to allow the text file to be accessed by multiple processes, but now when I open the text file using Process.Start, it doesn't show the lines that are being written using the StreamWriter. Any help very much appreciated.
Code:
Dim ExportLog As String = "C:\ExportLog.txt"
If System.IO.File.Exists(ExportLog) Then
System.IO.File.Delete(ExportLog)
End If
Using writeStream = System.IO.File.Open(ExportLog,
FileMode.OpenOrCreate, FileAccess.ReadWrite,
FileShare.ReadWrite), Write As New StreamWriter(writeStream)
Write.WriteLine("Starting")
End Using
Dim MyLog As Process = Process.Start(ExportLog)
After some great arguments made by other users in this question: How to write to a text file inside of the application, I decided to not use a resource file, instead create a file in a folder & then read/write from there.
Although, for some reason, I can't seem to write to the file in question, it keeps throwing an exception telling me the file is already in use by another process.
Here's the code which I use for writing to this file.
If System.IO.File.Exists(credentials) Then
Dim objWriter As New System.IO.StreamWriter(credentials, False)
objWriter.WriteLine(remember)
objWriter.Close()
Else
System.IO.Directory.CreateDirectory(Mid(My.Application.Info.DirectoryPath, 1, 1) & ":\ProgramData\DayZAdminPanel")
System.IO.File.Create(credentials)
Dim objWriter As New System.IO.StreamWriter(credentials, False)
objWriter.WriteLine(remember)
objWriter.Close()
End If
Any ideas on how I can write to the text file in question?
There's a good chance that a previous iteration of your application failed to properly close access to the file in the StreamWriter. Since your constructor is set to overwrite (and not append) to the file, this could be the source.
Try setting up your application with a "Using" statement to properly open/close the file:
If System.IO.File.Exists(credentials) Then
Using objWriter As StreamWriter = New StreamWriter(credentials, False)
objWriter.WriteLine(remember)
objWriter.Close()
End Using
Else
System.IO.Directory.CreateDirectory(Mid(My.Application.Info.DirectoryPath, 1, 1) & ":\ProgramData\DayZAdminPanel")
System.IO.File.Create(credentials)
Using objWriter As StreamWriter = New StreamWriter(credentials, False)
objWriter.WriteLine(remember)
objWriter.Close()
End Using
End If
It does look rather redundant to have a Using block and a close statement, but this ensures access to your file even if an exception occurs.
You are trying to create a directory in the common application data directory. This directory should be found using the Environment class methods and enums because is different between operating systems. However you use the value credentials for the filename. I suppose that you want to store your datafile in the common application directory and not in a place where there is no permission to write data files (Like C:\program files (x86)).
Then, to avoid problems with file stream not correctly closed try to use the Using statement that assures a correct closure and disposal of your file resource (No need to call close inside a Using).
Also, notice that StreamWriter is perfectly capable to create the file if it doesn't exists or if you wish to overwrite the previous contents (passing false for the Append flag).
So your code could be reduced to these lines.
' Get the common application data directory (could be different from Win7 and XP)
Dim workDir = Environment.GetFolderPath(Environment.SpecialFolder.CommonApplicationData)
' Combine with your own working data directory
workDir = Path.Combine(workdir, "DayZAdminPanel")
' Create if not exists
If Not Directory.Exists(workDir) Then
Directory.CreateDirectory(workDir)
End If
' Create/Overwrite your data file in a subfolder of the common application data folder
Dim saveFile = Path.Combine(workDir, Path.GetFileName(credentials))
Using objWriter = New System.IO.StreamWriter(saveFile, False)
objWriter.WriteLine(remember)
End Using
File.Create returns an opened FileStream that you should be passing into the StreamWriter constructor on the subsequent, rather than passing the filename again, or you can just omit the File.Create call altogether.
You might want to look into a Using block for the StreamWriter so it gets predictably closed.
I have written a vb program a few years ago and now as I get started with vb again i am hitting a "snag". With sequential files. I am trying to load a file in to the vb program with the file dialog box.
NOTE:I am using structures
Dim FileDialog as new openFileDialog
Dim MyStream as Stream = nothing
Dim FileLocation as string 'this is to save the file location
if( FileDialog.ShowDialog() = DialogResults.OK)Then
FS = new FileStream(FileLocation, FileMode.open, fileaccess.Read)
BF = new BinaryFromatter
While FS.Position < FS.Length
Dim temp as unit
...'Please note that this is where the file reads the structures data.It is to much code to write in.
When I run the program I can create a file and save it with the data in and I can load it with the Dialog box, The problem is when I run the program again and try to load it. It just wont run the file or load it(Remember I created the file with this program and saved)
How do I get this to work?
Make sure you have closed the file after writing and reading the data the first time, and make sure you are using the correct path (FileLocation).
Exit Visual Studio between the first and second times you run the program. If it works then, then you know you are not closing the file properly.
Set a breakpoint at the new FileStream assignment and check the value of FileLocation. Is it the same as it was when the file was written?
Check the error message, if there is one, and see if that tells you anything.