Create a text file and write to it in C#

Question

Hi I tried create and write a text file in C# but I get this error.

The process is being used by another process 'D:\SampleFolder\Sample.txt' can not access the file.

public void WriteToLog(string ClassName, string Message)
{
    string path = @"D:\SampleFolder\" + ClassName + ".txt";

    if (!File.Exists(path))
    {
        File.Create(path);
        TextWriter tw = new StreamWriter(path,true);
        tw.WriteLine(DateTime.Now.ToString() + " " + "Class:" + " " + ClassName + " " + "Message:" + Message);
        tw.Close();
    }

    else if (File.Exists(path))
    {
        TextWriter tw = new StreamWriter(path, true);
        tw.WriteLine(DateTime.Now.ToString() + " " + "Class:" + " " + ClassName + " " + "Message:" + Message);
        tw.Close();
    }
}

..
..
try
{

}
catch (Exception ex)
{       
    WriteToLog(this.GetType().Name, ex.Message);
}

Make sure that file is not open by another application. It sounds like it is! Some apps are greedy and once opened they lock it so that things cannot change it. Close that app and try again! — Belogix, Jan 23 '15 at 16:25
Do you have the text file open in a text editor or something that bars any other programs from modifying it? — EnragedTanker, Jan 23 '15 at 16:26
`File.AppendAllText()` would simplify what you have to 1 line — Alex K., Jan 23 '15 at 16:27

score 3 · Accepted Answer · answered Jan 23 '15 at 16:28

3

You are issuing a File.Create before creating a TextWriter.

File.Create(path);
TextWriter tw = new StreamWriter(path,true);

File.Create by default creates a file and leaves it locked, so your TextWriter can't access to it.

From the documentation:

The FileStream object created by this method has a default FileShare value of None; no other process or code can access the created file until the original file handle is closed.

File.Create returns a stream, so either use that stream to write to the file (instead of passing the path to the TextWriter), or just don't call File.Create at all, and let the StreamWriter create the file.

answered Jan 23 '15 at 16:28

Jcl

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3

Also use `using` statement. Also, for logging, use existing libraries. – Dialecticus Jan 23 '15 at 16:30
@Dialecticus agree on `using`. Don't necessarily on using existing libraries for logging. I was just answering the question as of why the file was locked so that the OP can learn what the problem was: I'd not use the method he uses to write a single line of text to a file anyway :-) – Jcl Jan 23 '15 at 16:32

Create a text file and write to it in C#

1 Answers1