I am making a class that is to help with saving some strings to a local text file (I want to append them to that file and not overwrite so that it is a log file). When I write with the streamwriter to find the end of the previous text, I get an error "the file is not available as it is being used by another process". I looked into this problem on MSDN and I got very little help. I tried to eliminate some variables so I removed the streamreader to check was that the problem and it was. When I tried to write to the file then it worked and I got no error so this made me come to the conclusion that the problem arose in the streamreader. But I could not figure out why?
Here is the code:
Public Sub SaveFile(ByVal Task As String, ByVal Difficulty As Integer, ByVal Time_Taken As String)
Dim SW As String = "C:/Program Files/Business Elements/Dashboard System Files/UserWorkEthic.txt"
Dim i As Integer
Dim aryText(3) As String
aryText(0) = Task
aryText(1) = Difficulty
aryText(2) = Time_Taken
Dim objWriter As System.IO.StreamWriter = New System.IO.StreamWriter(SW, True)
Dim reader As System.IO.StreamReader = New System.IO.StreamReader(SW, True)
reader.ReadToEnd()
reader.EndOfStream.ToString()
For i = 0 To 3
objWriter.WriteLine(aryText(reader.EndOfStream + i))
Next
reader.Close()
objWriter.Close()
End Sub
As Joel has commented on the previous answer it is possible to change the type of locking.
Otherwise building on what Neil has suggested, if to try to write to a file with a new reader it is difficult not to lose the information already within the file.
I would suggest you rename the original file to a temporary name, "UserWorkEthicTEMP.txt" for example. Create a new text file with the original name. Now; read a line, write a line, between the two files, before adding your new data onto the end. Finally Delete the temporary file and you will have the new file with the new details. If you have an error the temporary file will serve as a backup of the original. Some sample code below:
Change file names
Dim Line as string
line=Reader.readline
Do until Line=nothing
objwriter.writeline(line)
line=reader.readline
loop
add new values on the end and remove old file
You are trying to read and write to the same file and this is causing a lock contention. Either store the contents of the file into a variable and then write it back out including your new data to the file.
Psuedo
Reader.Open file
String content = Reader.ReadToEnd()
Reader.Close
Writer.Open file
Loop
Writer.Write newContent
Writer.Close
Related
I am using a legacy application where all the source code is in vb.net. I am checking if the file exists and if the condition is true replace all the " in the contents of the file. For instance "text" to be replaced as text. I am using the below code.
vb.net
Dim FileFullPath As String
FileFullPath = "\\Fileshare\text\sample.txt"
If File.Exists(FileFullPath) Then
Dim stripquote As String = FileFullPath
stripquote = stripquote.Replace("""", "").Trim()
Else
'
End If
I get no errors and at the same time the " is not being replaced in the content of the file.
Data:
ID, Date, Phone, Comments
1,05/13/2021,"123-000-1234","text1"
2,05/13/2021,"123-000-2345","text2"
3,05/13/2021,"123-000-3456","text2"
Output:
1,05/13/2021,123-000-1234,text1
2,05/13/2021,123-000-2345,text2
3,05/13/2021,123-000-3456,text2
You can read each line of the file, remove the double-quotes, write that to a temporary file, then when all the lines are done delete the original and move/rename the temporary file as the filename:
Imports System.IO
'...
Sub RemoveDoubleQuotes(filename As String)
Dim tmpFilename = Path.GetTempFileName()
Using sr As New StreamReader(filename)
Using sw As New StreamWriter(tmpFilename)
While Not sr.EndOfStream
sw.WriteLine(sr.ReadLine().Replace("""", ""))
End While
End Using
End Using
File.Delete(filename)
File.Move(tmpFilename, filename)
End Sub
Add error handling as desired.
The best way to go about this depends on the potential size of the file. If the file is relatively small then there's no point processing it line by line and certainly not using a TextFieldParser. Just read the data in, process it and write it out:
File.WriteAllText(FileFullPath,
File.ReadAllText(FileFullPath).
Replace(ControlChars.Quote, String.Empty))
Only if the file is potentially large and reading it all in one go would require too much memory should you consider processing it line by line. In that case, I'd go this way:
'Let the system create a temp file.
Dim tempFilePath = Path.GetTempFileName()
'Open the temp file for writing text.
Using tempFile As New StreamWriter(tempFilePath)
'Open the source file and read it line by line.
For Each line In File.ReadLines(FileFullPath)
'Remove double-quotes from the current line and write the result to the temp file.
tempFile.WriteLine(line.Replace(ControlChars.Quote, String.Empty))
Next
End Using
'Overwrite the source file with the temp file.
File.Move(tempFilePath, FileFullPath, True)
Note the use of File.ReadLines rather than File.ReadAllLines. The former will only read one line at a time where the latter reads every line before you can process any of them.
EDIT:
Note that this:
File.Move(tempFilePath, FileFullPath, True)
only works in .NET Core 3.0 and later, including .NET 5.0. If you're targeting .NET Framework then you have three other options:
Delete the original file (File.Delete) and then move the temp file (File.Move).
Copy the temp file (File.Copy) and then delete the temp file (File.Delete).
Call My.Computer.FileSystem.MoveFile to move the temp file and overwrite the original file in one go.
TextFieldParser is probably the way to go.
Your code with a few changes.
Static doubleQ As String = New String(ControlChars.Quote, 2)
Dim FileFullPath As String
FileFullPath = "\\Fileshare\text\sample.txt"
If IO.File.Exists(FileFullPath) Then
Dim stripquote As String = IO.File.ReadAllText(FileFullPath)
stripquote = stripquote.Replace(doubleQ, "").Trim()
Else
'
End If
Note the static declaration. I adopted this approach because it confused the heck out of me.
I have a CSV file in my project resources which I want to read using FileIO.TextFieldParser
I tried Dim parser = new TextFieldParser(My.Resources.ArticlesCSV), but since TextFieldParser expects either a path (as string) or a stream, this is not working.
I guess one possibility is to convert the resource to a stream, but I cannot find how to do that...
What is the best way to get this working?
You can create a new instance of IO.StringReader which is of type TextReader that TextFieldParser will accept. Just pass your CSV file (Thanks to AndrewMorton)
Using strReader As New IO.StringReader(My.Resources.ArticlesCSV)
Using textparser As New TextFieldParser(strReader)
textparser.Delimiters = {","}
While Not textparser.EndOfData
Dim curRow = textparser.ReadFields()
' Do stuff
End While
End Using
End Using
I am trying to writeline into a text file this works accept it appears to overwrite the last line each time. I would like it to write to the next line instead of overwriting. Here is the code I'm using
Dim FileNumber As Integer = FreeFile()
FileOpen(FileNumber, "c:\Converted.txt", OpenMode.Output)
PrintLine(FileNumber, convertedDir)
FileClose(FileNumber)
You are using an old (VB6/VBA) code, better use the .NET StreamWriter:
Dim append As Boolean = True
Using writer As System.IO.StreamWriter = New System.IO.StreamWriter("c:\Converted.txt", append)
writer.WriteLine(convertedDir)
End Using
append indicates whether the given file should be appended. Nonetheless, as suggested by Boris B., you can set this variable always to True because StreamWriter is capable to deal with both situations (existing file or not) automatically.
In any case, I am including below the "theoretically right" way to deal with StreamWriter (by changing the append property depending upon the fact that the given file is present or not):
Dim append As Boolean = False
Dim fileName As String = "c:\Converted.txt"
If (System.IO.File.Exists(fileName)) Then
append = True
End If
Using writer As System.IO.StreamWriter = New System.IO.StreamWriter(fileName, append)
writer.WriteLine(convertedDir) 'Writes to a new line
End Using
For a quick solution based on existing code change the line
FileOpen(FileNumber, "c:\Converted.txt", OpenMode.Output)
to
FileOpen(FileNumber, "c:\Converted.txt", OpenMode.Append)
However, you should really update your method of writing files, since FileOpen and similar are there just for compatibility with older VB & VBA programs (and programmers :). For a more modern solution check out varocarbas' answer.
I've nicked some code from msdn to write and read to an xml file to persist my data, but I need a little help with it. I have a dynamic array called darr. As I understand it, I use this code to store it in an xml file:
Dim objStreamWriter As New StreamWriter("C:\temp\test.xml")
Dim x As New XmlSerializer(darr.GetType)
x.Serialize(objStreamWriter, darr)
objStreamWriter.Close()
And this to read it:
Dim objStreamReader As New StreamReader("C:\temp\test.xml")
darr = x.Deserialize(objStreamReader)
objStreamReader.Close()
The thing is, I want the app to read from the file on startup, which means the second block gets called first and if the file doesn't exit yet, it throws an exception. (The first block automatically creates the file if not found.) So two questions:
Is there a way to have the app create the file automatically the first time it runs?
Since the file will be empty... will the code work? If not, is there a workaround? (Okay that's three questions!)
If Not File.Exists("C:\temp\test.xml") Then
' Create the file.
Dim file As System.IO.FileStream
file = System.IO.File.Create("C:\temp\test.xml")
Else
Dim objStreamWriter As New StreamWriter("C:\temp\test.xml")
Dim x As New XmlSerializer(darr.GetType)
x.Serialize(objStreamWriter, darr)
objStreamWriter.Close()
End If
I make a search program for searching a list of files in a computer and then copy the file into a store folder. The file name could be "*11*2.txt" As long as the program find this pattern, it should copy to the store folder. The problem is that I don't know the exactly name of the file before the search and I don't want to rename the file, I don't know how to save the file. Please help
I use the following to find the file, which does its work
Public Sub DirSearch(ByVal sDir As String, ByVal FileName As String)
Dim To_Path As String
To_Path = Form1.TextBox5.Text
For Each foundFile As String In My.Computer.FileSystem.GetFiles(sDir, FileIO.SearchOption.SearchAllSubDirectories, FileName)
Copy2Local(foundFile, To_Path)
Next
End Sub
Here is the current version of the Copy2Local (Note: it is not working right)
Public Sub Copy2Local(ByVal Copy_From_Path As String, ByVal Copy_To_Path As String)
' Specify the directories you want to manipulate.
Try
Dim fs As FileStream = File.Create(Copy_From_Path)
fs.Close()
' Copy the file.
File.Copy(Copy_From_Path, Copy_To_Path)
Catch
End Try
End Sub
First, you should check if ToPath is a valid directory since it's coming from a TextBox:
Dim isValidDir = Directory.Exists(ToPath)
Second, you can use Path.Combine to create a path from separate (sub)directories or file-names:
Dim copyToDir = Path.GetDirectoryName(Copy_To_Path)
Dim file = Path.GetFileName(Copy_From_Path)
Dim newPath = Path.Combine(copyToDir, file)
http://msdn.microsoft.com/en-us/library/system.io.path.aspx
(disclaimer: typed from a mobile)
To answer your question: You can get the file name with Path.GetFileName. Example:
Dim fileName As String = Path.GetFileName(foundFile)
However, there's a bunch of other things wrong with your code:
Here,
Dim fs As FileStream = File.Create(Copy_From_Path)
fs.Close()
you are overwriting your source file. This does not seem like a good idea. ;-)
And here,
Try
...
Catch
' Do Nothing
End Try
You are throwing away exceptions that would help you find and diagnose problems. Don't do that. It makes debugging a nightmare.
In vb.net, I'm using the following code to find the filename
Textbox1.Text = New FileInfo(OpenFileDialog.FileName).Name
this code work fine with open file dialog box