C# Client/Server: using Streamreader/writer

Question

I'm relatively new to C# but here goes:

I am developing a remote file service client/server console application in C# which is supposed to exchange messages using synchronous sockets.

One of the main problems (even thought it might seem simple) is to return a string from the server, to the client using streamreader/streamwriter.

The application user a command line interface with options (from a switch statement) to execute actions. I.e. typing 1 and enter would execute the code to send the string from the server to the client.

Below is a sample code from the client:

        try
        {
            using (TcpClient client = (TcpClient)clientObject)
            using (NetworkStream stream = client.GetStream())
            using (StreamReader rd = new StreamReader(stream))
            using (StreamWriter wr = new StreamWriter(stream))
            {

                string menuOption = rd.ReadLine();


                switch (menuOption)
                    {
                        case "1":
                        case "one":
                            string passToClient = "Test Message!";
                            wr.WriteLine(passToClient);
                            break;
                   } 
                      while (menuOption != "4");
               }
         }

I understand the code I posted is just a snippet of the program, but it would take up a fair amount of space and was hoping you can gather what I mean from this, if not I will post more.

This is just to give a general idea of what I am going for,

I appreciate any help / advice you can give. Its not so much code examples I'm looking for (although a little would help) but more some explanation on streamreader/writer as I cant seem to understand much of what is online.

Thanks.

Ian · Accepted Answer · 2015-11-10 13:07:49Z

5

Whenever you use StreamWriter you need to Flush() the contents of the stream. I'll quote MSDN as the reason becomes quite clear:

Clears all buffers for the current writer and causes any buffered data to be written to the underlying stream.

You can call it quite simply like:

wr.flush();

edited Nov 10, 2015 at 13:07

Ian

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answered Nov 10, 2015 at 12:18

Xyed Xain Haider

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Comments

Frank Coyle · Accepted Answer · 2014-03-27 00:23:33Z

4

I think you're just missing a wr.flush(); but this article should cover everything you need:

http://thuruinhttp.wordpress.com/2012/01/07/simple-clientserver-in-c/

answered Mar 27, 2014 at 0:23

Frank Coyle

1136 bronze badges

1 Comment

KFL Over a year ago

Ah, I missed Flush().

Vincent · Accepted Answer · 2020-09-16 11:04:51Z

4

Solution can be simpler:

StreamWriter wr = new StreamWriter(stream) { AutoFlush = true }

answered Sep 16, 2020 at 11:04

Vincent

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Comments

Chi_Town_Don · Accepted Answer · 2014-03-27 19:38:06Z

I just ran a test using your code, and it works fine, I can step right into the "one" case statement.

I am guessing you are either not including the line-break in the string you are sending, or you just have the TcpClient or TcpListener configured wrong.

Here is the Client-Side code for my test:

        TcpClient client = new TcpClient("127.0.0.1", 13579);
        string message = "one" + Environment.NewLine;
        Byte[] data = System.Text.Encoding.ASCII.GetBytes(message);
        NetworkStream stream = client.GetStream();
        stream.Write(data, 0, data.Length);

Here is the Server-Side:

        IPAddress localAddr = IPAddress.Parse("127.0.0.1");
        TcpListener server = new TcpListener(localAddr, 13579);
        server.Start();

        TcpClient client = server.AcceptTcpClient();
        using (client)
        using (NetworkStream stream = client.GetStream())
        using (StreamReader rd = new StreamReader(stream))
        using (StreamWriter wr = new StreamWriter(stream))
        {
            string menuOption = rd.ReadLine();
            switch (menuOption)
            {
                case "1":
                case "one":
                    string passToClient = "Test Message!";
                    wr.WriteLine(passToClient);
                    break;
            }
            while (menuOption != "4") ;
        }

Just run the server-side code first, which will block while waiting for connection and then while waiting for data. Then run the client-side code. You should be able to catch a breakpoint on the switch().

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