I had created and text file using (AFL SCRIPTING LANGUAGE) this script will update (write) to a text file every 5 seconds. I will try to read file using vb.net, when I run the vb.net code form visual studio, everything works fine but (AFL script not able to update the text file), here is my vb.net code:
Dim FILE_NAME As New FileStream("C:\myreport\myfile.TXT", FileMode.Open, FileAccess.Read, FileShare.Read)
REM Dim FILE_NAME As String = "C:\myreport\myfile.TXT"
REM Dim TextLine As String
REM If System.IO.File.Exists(FILE_NAME) = True Then
Dim objReader As New System.IO.StreamReader(FILE_NAME)
Do While objReader.Peek() <> -1
MYSTRING(I) = objReader.ReadLine()
I = I + 1
Loop
REM End If
When I run the code above, ( AFL script not able to update the text file),
Put simply:
When I run the vb.net code (for accessing the text file), AFL script not able to update.
I had share read/write the folder (where the text file exists), no effect, same problem I am facing.
Unchecked "Enable visual studio hosting process", still problem not solved.
In .NET, the FileSystemWatcher class can help you with this problem. You can read the file each time the file watcher says that the files has changed. Here is the reference documentation for it.
You cannot read and write to a file from two processes at the same time. Well, technically you can, but it can lead to a race condition which is bad.
You need to implement some kind of shared locking mechanism around the file to prevent your two programs from fighting over it. Or, if you can guarantee that the consumer VB.NET program will have the file open for less than 5 seconds, you can go with MrAxel's solution and simply have the VB.NET program read the file every time it is updated.
Related
I am trying to import a text file into a rich text box for my Visual Basic project (Its a Windows Forms App (.Net Framework)). I copied the text information from the internet, and pasted it into notepad. Then I saved this in a folder I created called txtFiles inside the Bin folder of my project. However, when I used the FileOpen command, it gives me an error.
The code I used:
Dim strTemp As String = ""
rtbReference.Text = Nothing
FileOpen(1, "../txtFiles/Thriller.txt", OpenMode.Input)
Do Until EOF(1) = True
Input(1, strTemp)
rtbReference.Text = strTemp
Loop
FileClose(1)
Picture:
The error that I got when running my program
Any help would be appreciated, thank you so much
There are more easier methods of working with files in the 21st century. I mean the IO namespace provides a handful of methods.
Try any of the following. Add this at the top of your code file
Imports System.IO
Method 0: File.ReadAllText
Since the file you want to load is a plain tet file, I suggest you use this.
RichTextBox1.Text = File.ReadAllText(pathtofile)
Method 1: Richtextbox.LoadFile()
Someone (or something) has already posted the link to an article on this in the comments but i'm pretty sure you've not gone through it. Well here's how to use it
RichTextBox1.LoadFile(pathtofile)
I use this method for only rtf files but it was completely my decision.
Method 2 To n - 1
You need to know how to use a search engine as there are many methods out there that can be used such as the StreamReader and so on.
On a button click I have the following code to write what Is in my textboxes.
Dim file As System.IO.StreamWriter
file = My.Computer.FileSystem.OpenTextFileWriter("C:/Users/Nick/Documents/Dra.txt", False)
file.WriteLine(NameBasic)
file.WriteLine(LastBasic)
file.WriteLine(PhoneBasic)
file.WriteLine(NameEmer1)
On my form load, I load what is in the notepad from what was written, It is saying It is already being used(the file) which is true, how can I have two different functions(write, and read) manipulating the same file with out this error?
The process cannot access the file 'C:\Users\Nick\Documents\Dra.txt' because it is being used by another process.
And here is the code for my onformload
Dim read As System.IO.StreamReader
read = My.Computer.FileSystem.OpenTextFileReader("C:/Users/Nick/Documents/Dra.txt")
lblNameBasic.Text = read.ReadLine
I am sort of stuck on this problem, thank you
You need to close the file when you are done writing to it.
Dim file As System.IO.StreamWriter
file = My.Computer.FileSystem.OpenTextFileWriter("C:/Users/Nick/Documents/Dra.txt", False)
file.WriteLine(NameBasic)
file.WriteLine(LastBasic)
file.WriteLine(PhoneBasic)
file.WriteLine(NameEmer1)
file.Close()
To answer your question:
how can I have two different functions(write, and read) manipulating the same file with out this error?
If you really want to simultaneously read and write to the same file from two processes, you need to open the file with the FileShare.ReadWrite option. The My.Computer.FileSystem methods don't do that.¹
However, I suspect that you don't really wan't to do that. I suspect that you want to write and, after you are finished writing, you want to read. In that case, just closing the file after using it will suffice. The easiest way to do that is to use the Using statement:
Using file = My.Computer.FileSystem.OpenTextFileWriter(...)
file.WriteLine(...)
file.WriteLine(...)
...
End Using
This ensures that the file will be closed properly as soon as the Using block is left (either by normal execution or by an exception). In fact, it is good practice to wrap use of every object whose class implements IDisposable (such as StreamWriter) in a Using statement.
¹ According to the reference source, OpenTextFileWriter creates a New IO.StreamWriter(file, append, encoding), which in turn creates a new FileStream(..., FileShare.Read, ...).
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)
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.
I am working on a GUI for a simulation program. The simulation program is a single .exe which is driven by an input file (File.inp placed in the same directory).
The Original.inp file functions as a template from which the form reads all the values into an array. Then it changes these values reflecting the changes done by the user in the form. After that it writes all the new values to File.inp.
By pushing the "Run" button the Simulation.exe file is executed.
The folder structure looks like this:
root
|
|---input
| |
| |--Original.inp
|
|---GUI.exe
|---Simulation.exe
|---File.inp
Ideally I would supply only the GUI, the user would select the working directory and then the GUI.exe would create an input folder and extract the Original.inp and Simulation.exe in the appropriate locations. So far I have only managed to include Original.inp and Simulation.exe as "EmbeddedResources" in my VB project and I have let my code create an input folder in the working directory chosen by the user.
Can someone please explain to me how I can extract the .inp and .exe file into the correct directories? I've searched on google, tried File.WriteAllBytes and Filestream.WriteByte but did not get the desired results.
The problem with File.WriteAllBytes was that I could not point to the embedded resource ("Simulation.exe is not a member of Resources" and with Filestream.WriteByte I got a 0 kb file.
The question commenters are correct, this is probably a task best left for a setup program. However, that having been stated, in the interest of answering the question as asked I offer the following approach.
Contrary to your supposition in your question comment, you do need to "read" the embedded resource from the GUI's executable file, since it's an embedded resource and not an external resource. It won't magically extract itselt from the executable file. You need to do the manual read from the assembly and write to your specified locations. To do this, you need to read the resource using .Net Reflection, via the currently executing assembly's GetManifestResourceStream method.
The Simulation.exe file is a binary file so it must be handled as such. I assumed that the Orginal.inp file was a text file since it afforded the opportunity to demonstrate different types of file reads and writes. Any error handling (and there should be plenty) is omitted for brevity.
The code could look something like this:
Imports System.IO
Imports System.Reflection
Module Module1
Sub Main()
'Determine where the GUI executable is located and save for later use
Dim thisAssembly As Assembly = Assembly.GetExecutingAssembly()
Dim appFolder As String = Path.GetDirectoryName(thisAssembly.Location)
Dim fileContents As String = String.Empty
'Read the contents of the template file. It was assumed this is in text format so a
'StreamReader, adept at reading text files, was used to read the entire file into a string
'N.B. The namespace that prefixes the file name in the next line is CRITICAL. An embedded resource
'is placed in the executable with the namespace noted in the project file, so it must be
'dereferenced in the same manner.
Using fileStream As Stream = thisAssembly.GetManifestResourceStream("SOQuestion10613051.Original.inp")
If fileStream IsNot Nothing Then
Using textStreamReader As New StreamReader(fileStream)
fileContents = textStreamReader.ReadToEnd()
textStreamReader.Close()
End Using
fileStream.Close()
End If
End Using
'Create the "input" subfolder if it doesn't already exist
Dim inputFolder As String = Path.Combine(appFolder, "input")
If Not Directory.Exists(inputFolder) Then
Directory.CreateDirectory(inputFolder)
End If
'Write the contents of the resource read above to the input sub-folder
Using writer As New StreamWriter(Path.Combine(inputFolder, "Original.inp"))
writer.Write(fileContents)
writer.Close()
End Using
'Now read the simulation executable. The same namespace issues noted above still apply.
'Since this is a binary file we use a file stream to read into a byte buffer
Dim buffer() As Byte = Nothing
Using fileStream As Stream = thisAssembly.GetManifestResourceStream("SOQuestion10613051.Simulation.exe")
If fileStream IsNot Nothing Then
ReDim buffer(fileStream.Length)
fileStream.Read(buffer, 0, fileStream.Length)
fileStream.Close()
End If
End Using
'Now write the byte buffer with the contents of the executable file to the root folder
If buffer IsNot Nothing Then
Using exeStream As New FileStream(Path.Combine(appFolder, "Simulation.exe"), FileMode.Create, FileAccess.Write, FileShare.None)
exeStream.Write(buffer, 0, buffer.Length)
exeStream.Close()
End Using
End If
End Sub
End Module
You will also have to add logic to determine if the files have been extracted so it doesn't happen every time the GUI is invoked. That's a big reason why an installation program might be the correct answer.