Question

I am using streamwriter to write a string into stream. Now when I access the data from the stream, it adds “\0\0\0” characters to end of the content. I have to append the stream contents, so it creates problem as I am not able to remove these characters by trim() or remove() or replace() methods.

Below is the code I am using:

FOR WRITING :

using (MemoryMappedViewStream stream = mmf.CreateViewStream())
{
    using (StreamWriter writer = new StreamWriter(stream, System.Text.Encoding.Unicode))
    {
        try
        {
            string[] files = System.IO.Directory.GetFiles(folderName, "*.*", System.IO.SearchOption.AllDirectories);
            foreach (string str in files)
            {
                writer.WriteLine(str);
            }
            // writer.WriteLine(folderName);
        }
        catch (Exception ex)
        {
            Debug.WriteLine("Unable to write string. " + ex);
        }
        finally
        {
            mutex.ReleaseMutex();
            mutex.WaitOne();
        }
    }
}

FOR READING :

 StringBuilder sb = new StringBuilder();
            string str = @"D:\Other Files\Test_Folder\New Text Document.txt";
 using (var stream = mmf.CreateViewStream())
                {
                    System.IO.StreamReader reader = new System.IO.StreamReader(stream);
                    sb.Append(reader.ReadToEnd());
                    sb.ToString().Trim('\0');
                    sb.Append("\n" + str);
                }

How can I prevent this?

[UPDATES]
Writing

// Lock
            bool mutexCreated;
            Mutex mutex = new Mutex(true, fileName, out mutexCreated);
            if (!mutexCreated)
                mutex = new Mutex(true);
            try
            {
                using (MemoryMappedViewStream stream = mmf.CreateViewStream())
                {
                    using (BinaryWriter writer = new BinaryWriter(stream))
                    {
                        try
                        {
                            string[] files = System.IO.Directory.GetFiles(folderName, "*.*", System.IO.SearchOption.AllDirectories);
                            foreach (string str in files)
                            {
                                writer.Write(str);
                            }
                            writer.Flush();
                        }
                        catch (Exception ex)
                        {
                            Debug.WriteLine("Unable to write string. " + ex);
                        }
                        finally
                        {
                            mutex.ReleaseMutex();
                            mutex.WaitOne();
                        }
                    }
                }
            }
            catch (Exception ex)
            {
                Debug.WriteLine("Unable to monitor memory file. " + ex);
            }

Reading

StringBuilder sb = new StringBuilder();
            string str = @"D:\Other Files\Test_Folder\New Text Document.txt";
            try
            {
                using (var stream = mmf.CreateViewStream())
                {
                    System.IO.BinaryReader reader = new System.IO.BinaryReader(stream);
                    sb.Append(reader.ReadString());
                    sb.Append("\n" + str);
                }
                using (var stream = mmf.CreateViewStream())
                {
                    System.IO.BinaryWriter writer = new System.IO.BinaryWriter(stream);
                    writer.Write(sb.ToString());
                }
                using (var stream = mmf.CreateViewStream())
                {
                    System.IO.BinaryReader reader = new System.IO.BinaryReader(stream);
                    Console.WriteLine(reader.ReadString());
                }
            }
            catch (Exception ex)
            {
                Debug.WriteLine("Unable to monitor memory file. " + ex);
            }

Answer 1

Your combination of a MMF and TextWriter/TextReader, especially ReadToEnd() is not a good match.

A textReader needs the EOF concept of the underlying file and a MMF just does not supply that in the same way. You will get your strings stuffed with \0\0... up to the capacity of the MMF.

As a possible fix:

• collect the strings to write in a StringBuilder
• use a BinaryWriter to write it as 1 string
• read it back with a BinaryReader.

Another options is to use WriteLine/ReadLine and define some EOF marker (empty line or special string).

The BinaryWriter will prefix the string with a length-prefix so that the Reader knows when to stop.