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I'm making a simple client application in C#, and have reached a problem.

The server application sends a string in the format of "<number> <param> <param>" etc. In other words, the first symbol is an integer, and the rest are whatever, all are separated by one space each.

The problem I get, when reading this string, is that my program first reads a string with the , and then the next time I read I get the rest of the message. For example, if I were to do a writeline on what I receive, it would look like this: (if he sends "1 0 0 0")

1
 0 0 0

(EDIT: The formatting doesn't seem to permit this. The 1 is on a row of its own, the rest are supposed to be on the row below, including the space preceding the first 0)

I've run out of ideas how to fix this. Here's the method (I commented out some stuff I tried): http://pastebin.com/0bXC9J2f

EDIT (again): I forgot, it seems to work just fine when I'm in debug and just go through everything step by step, so I can't find any source of the problem that way.

Thomas
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  • You should *really* use the higher-level APIs. Specifically, those with `ReadLine`. :) – bzlm May 30 '11 at 17:14
  • I didn't know there were any in C#. I've been swearing over this whole byte[] thing since I came from Java where I could just read it as a string from the start. – Thomas May 30 '11 at 17:19
  • Just wrappa coupla `StreamWriter`s around the streams. Also don't forget to actually terminate your messages with newlines. – bzlm May 31 '11 at 09:43
  • @Thomas: Are you happy with the answer? – jgauffin Mar 18 '16 at 08:50
  • @jgauffin yes! It was precisely what I was looking for at the time. I wasn't very experienced, so I didn't know how to properly formulate the question. Sorry for the very late response. – Thomas Feb 24 '17 at 12:41
  • @Thomas: Feel free to accept the answer ;) – jgauffin Feb 24 '17 at 12:51
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    @jgauffin sorry about that! It completely slipped my mind. Accepted! :) – Thomas Feb 27 '17 at 10:19

2 Answers2

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TCP is stream based and not message based. One Read can contain any of the following alternatives:

  • A teeny weeny part of message
  • A half message
  • Excactly one message
  • One and a half message
  • Two messages

Thus you need to use some kind of method to see if a complete message have arrived. The most common methods are:

  • Add a footer (for instance an empty line) which indicates end of message
  • Add a fixed length header containing the length of the message
jgauffin
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1

If your protocol is straight TCP, then you cannot send messages, strings or anything else except octet, (byte) streams. Does your 'string' have a null at the end? If so, you need to append received data until the null arrives, then you have your message.

If this is your problem, then you should code your protocol so that it works no matter how many read calls are made on the socket, eg. if a null-terminated string of [99 data bytes+#0] is sent by the server, your protocol should be able to assemble the correct string if 100 bytes are returned in one call, 1 byte is received in 100 calls, or anything in between.

Rgds, Martin

Martin James
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