"R" is not regestering as Equal to "R" when send over TCP connection

Question

I am trying to have a client send a command to my service, that command being "R". But when I try to make an IF statement it will not register the "R" that came in via TCP as being equal to a string R that I have made in my program. Here is some of my code.

    byte[] message = new byte[1024];
        byte[] command = Encoding.ASCII.GetBytes("R");
        stream.Read(message, 0, message.Length);
        string messageIn = Encoding.ASCII.GetString(message);
        //updateUI("New Message =  " + messageIn);
        string commandString = Encoding.ASCII.GetString(command);

         if (Encoding.ASCII.GetString(message) == Encoding.ASCII.GetString(command))

As you can see, I was of the impression that taking "R" into bytes and then out of bytes would have caused this problem hence the giant if statement. However not a single one of these conditions returns true as my if block never runs.

I know that it is returning "R" because when I output it to a textbox, that is what gets printed. Is the very act of transfering it VIA tcp changing the string somehow?

Answer 1

Aside from the vast number of pointless comparisons you're making, the first problem is that you're ignoring the result of Stream.Read... and instead creating a string out of the whole 1024 bytes within message. If you change it to:

int bytesRead = stream.Read(message, 0, message.Length);
string messageIn = Encoding.ASCII.GetString(message, 0, bytesRead);

... then you'd be in a much better position. However, that's probably still not good enough, unless that's all that's going to be sent. You're dealing with a stream, but I suspect you're thinking about it as if it's message-oriented - as if a single Write on one end of the connection will map to a single Read on the other end. That's not how stream-oriented protocols work. If you have a logical "message" then when reading from the stream you might end up with part of a message, multiple messages, anything. Common ways of fixing this are:

• Include a length prefix before each message
• Use a separator (e.g. a line break for text-based protocols)

See Marc Gravell's blog post on this for more details.

Additionally, if your protocol is text-based, it would be a good idea to create a StreamReader around the stream so that you can just read text (e.g. a line at a time) instead of converting all over the place.