How do I close or re-access a Text file ?

Question

2.50/5 (2 votes)

See more:

VS2010

I am reading a Text file and checking the contents, in this instance all lines should be a maximum of 16 bytes in length. If there is invalid data then my form is redisplayed and the user can edit the text file before re-processing it. However, as the file has already been opened, my code doesn't work, it throws an exception that the file is in use ... and yes, I can see exactly why, but how do I handle / get around it ?!?

VB

Dim myTeamCount As Int16 = 0
Dim myTextFile As New System.IO.FileStream(OpenFileDialog1.FileName, IO.FileMode.Open)
Dim myReader As New System.IO.StreamReader(myTextFile)
Dim List As New List(Of String)
Do While myReader.Peek >= 0
    If myReader.ReadLine.Length > 16 Then
        MessageBox.Show("Record Longer Than 16 Characters in This File - " & myReader.ReadLine & " - Edit & Retry.", "ERROR")
        Me.Refresh()
        Exit Do
    End If
    myTeamCount = myTeamCount + 1
    List.Add(myReader.ReadLine)
Loop

Thanks in advance ...

Posted 19-Jul-12 5:44am

Gary Heath

Add a Solution

Comments

[no name] 19-Jul-12 11:46am

Any reason you could not read the entire file all at once?

Gary Heath 19-Jul-12 11:55am

After I have checked every record, I then have to check the number of records, depending on a criteria that the user entered earlier, and if there is the correct number of records, then I want to write all of the stored records to a database Table.

[no name] 19-Jul-12 11:59am

Yes I understand that. I would just use File.ReadAllText which gives you all of the file contents in an array of strings. Process the array and then when everything is correct, write the file back out from the array. Totally gets rid of this opening and closing files all the time and coordinating the process.

lewax00 19-Jul-12 12:04pm

File.ReadAllLines might be more appropriate in this case.

Gary Heath 19-Jul-12 12:06pm

OK, that's what AlluvialDeposit said, but he didn't explain ... I was looking to do this via an Array in the first place, but I kept reading that this " list (of t)" method was better !!! So many different ways of doing things in this language !!! I'll get googling, thanks ...

ZurdoDev 19-Jul-12 11:53am

Since they can edit it you should reprocess the whole file anyway. So, close the file, let them edit, and then do it again.

Gary Heath 19-Jul-12 11:58am

But I don't know how to Close it, that's the question ... the way it is coded it is Dimmed as New, so the next time it processes this code, it already exists (or is open, or unusable, anyway !) ...

StianSandberg 19-Jul-12 11:59am

myReader.Close()
myReader.Dispose()

lewax00 19-Jul-12 12:03pm

myReader.Dispose() is redundant, Close already calls it (see http://msdn.microsoft.com/en-us/library/system.io.stream.close.aspx ).

StianSandberg 19-Jul-12 11:54am

You should dispose your reader. Or read file with System.IO.File.ReadAllText()

Gary Heath 19-Jul-12 12:03pm

Can you please explain why (... and how !) ? It's taken me most of today just to fins out how to do this, I don't want to go changing it unless I have a good reason ...

1 solution

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

lewax00 · Accepted Answer · 2012-07-19T05:55:00

Solution 1

You need to close the file before you can open it again, something like this should work:

VB

Dim myTeamCount As Int16 = 0
Dim myTextFile As New System.IO.FileStream(OpenFileDialog1.FileName, IO.FileMode.Open)
Dim myReader As New System.IO.StreamReader(myTextFile)
Dim List As New List(Of String)
Do While myReader.Peek >= 0
    If myReader.ReadLine.Length > 16 Then
        MessageBox.Show("Record Longer Than 16 Characters in This File - " & myReader.ReadLine & " - Edit & Retry.", "ERROR")
        myReader.Close()
        Me.Refresh()
        Exit Do
    End If
    myTeamCount = myTeamCount + 1
    List.Add(myReader.ReadLine)
Loop

Posted 19-Jul-12 5:55am

lewax00

Comments

Gary Heath 19-Jul-12 12:33pm

This does indeed resolve the problem, but whilst running the logic through Debug, I added a MessageBox to display each record as it is processed, and the first record it displays is Record 2, then when it finds the record that is longer than 16, which is the 4th record, it displays the 5th record, so something is dodgy about my code !!! I'm off to research how to use the File.ReadAllText & File.ReadAllLines that have been suggested ... thanks to everybody for their help.

lewax00 19-Jul-12 12:52pm

What you should be doing is storing the result of myReader.ReadLine in a string, because when you call it once to get the length, then again in the MessageBox call (which tells it to read the next line). I'd give you a code example but I haven't touched VB in years, so I don't remember exactly how right now. Or use System.IO.File.ReadAllLines to simplify it all ( http://msdn.microsoft.com/en-us/library/s2tte0y1.aspx )

Gary Heath 19-Jul-12 12:57pm

Yes, just found how to use ReadAllLines ... so much easier !!! Thanks again ...