can c++ tcpserver receive unsigned char?

Question

Currently I have a c# tcpclient and a c++ tcpserver, but I can only read chars from the stream at the server side thus all the data will be casted to char. Since c++ char is a signed 8-bit integer, but c# client sends byte, which is unsigned 8-bit integer, so all the data >=128 sent from client cannot be received correctly at server side. Example:

        char[] textChars = text.ToCharArray();
        byte[] textBytes = new byte[textChars.Length *2];
        byte low;
        byte high;
        UInt16 current;
        for (int i = 0; i < textChars.Length; i++)
        {
            current = (UInt16)textChars[i];
            high = (byte)(current / 256);
            low = (byte)(current % 256);
            textBytes[i * 2] = high;
            textBytes[i * 2 + 1] = low;
        }

        currentStream.Write(textBytes, 0, textBytes.Length);
        currentStream.Flush();

This is at client side, and I print out what I received at server side as a signed int: if i send a char with its ascii code = 136, which will become 2 bytes:0,136. but at server side, it prints 0, -22. So is there a way to have c++ stream read unsigned char? or is there another way to solve this? Thanks for helping!

paxdiablo paxdiablo · Accepted Answer · 2013-06-18T04:52:09

All you're getting over the TCP connection is raw data, it's how you choose to interpret it that decides what it looks like.

Easiest solution is to probably cast it before printing/using with something like:

signed char val = -22;               // emulate receipt of signed char.
printf ("%d\n", (unsigned char)val); // cast to change interpretation.

can c++ tcpserver receive unsigned char?

2 Answers