how to clear text file content c#

Question

i want clear text file contet with this method

private void writeTextFile(string filePath, string text)
{
    if (!File.Exists(filePath))
    {
        File.Create(filePath).Close();

    }
    using (StreamWriter tw = new StreamWriter(filePath))
    {
        File.WriteAllText(filePath,"");
        tw.WriteLine(text);
        tw.Close();
    }
}

but i get this error

The process cannot access the file  because it is being used by another process.

but this not open in anywhere ,

please help me thank's

Answer 1

That's because you're creating a StreamWriter, then using File.WriteAllText. Your File is already being accessed with the StreamWriter.

File.WriteAllText does just that, writes the entire string you pass to it to a file. StreamWriter is unnecessary if you're going to use File.WriterAllText.

If you don't care about overwriting an existing file, you can do this:

private void writeTextFile(string filePath, string text)
{
    File.WriteAllText(filePath, text);
}

If you want to use StreamWriter (which, by the way, File.WriteAllText uses, it just hides it), and append to the file, you can do this (from this answer):

using(StreamWriter sw = File.AppendText(path))
{
    tw.WriteLine(text);
}

Answer 2

You can use StreamWriter for creating a file for write and use Truncate to write with clearing previous content.

StreamWriter writeFile;
writeFile = new StreamWriter(new IsolatedStorageFileStream(filename, FileMode.Truncate, myIsolatedStorage));
writeFile.WriteLine("String");
writeFile.Close();

This use FileMode.Truncate

Truncate Specifies that an existing file it to be opened and then truncated so that its size is zero bytes.

Answer 3

Assuming that your file already exists and you want to clear its contents before populating it or whatever, I found the best way to do this with StreamWriter is..

// this line does not create test.txt file, assuming that it already exists, it will remove the contents of test.txt 
Dim sw As System.IO.StreamWriter = New System.IO.StreamWriter(Path.GetFullPath(C:\test.txt), False)

// this line will now be inserted into your test.txt file
sw.Write("hey there!")

Answer 4

// I decided to use this solution
// this section is to clear MyFile.txt
     using(StreamWriter sw = new StreamWriter(@"MyPath\MyFile.txt", false))
     {
       foreach(string line in listofnames)
       {
          sw.Write(""); // change WriteLine with Write
       }
        sw.Close();
      }
    // and this section is to copy file names to MyFile.txt
        using(StreamWriter file = new StreamWriter(@"MyPath\MyFile.txt", true))
        {
        foreach(string line in listofnames)
        {
            file.WriteLine(line);
        }
      }