how do i send and receive a classType over aTcp network in Qt.

[ssmny]

Qt problem
Hello all,
i would like to know how i can prepair(or encode) a class type for sending over a TCP connection. and when sent, how do i decode that info at the other end. That should be done in Qt (c++).
Thanks
I am sorry, i dont have any example, but if you have any that explains this situation, i will be very greatifull.

[Banfa]

Serialise (encode) or marshal the class data into a byte array. Send the array then at the other end deserialise (decode) or unmarshal the received byte array back into a class.

[ssmny]

thanks banfa,
could u please give me an example of how i would do that. am not familia with Qt. I have have even failed getting a start.

[Banfa]

Serialisation is not as complex as it sounds, you just split the data up into bytes so for a 4 byte long variable it would look something like

long startValue, endvalue;
unsigned char buffer[4];

//Serialise to big endian data buffer
startValue = 54321;

buffer[0] = (unsigned char)((startValue >> 24) & 0xFF);
buffer[1] = (unsigned char)((startValue >> 16) & 0xFF);
buffer[2] = (unsigned char)((startValue >> 8) & 0xFF);
buffer[3] = (unsigned char)(startValue & 0xFF);

//Deserialise from big endian data buffer
endvalue  = ((long)buffer[0]) << 24;
endvalue |= ((long)buffer[1]) << 16;
endvalue |= ((long)buffer[2]) << 8;
endvalue |= (long)buffer[3];

Just do that for all the POD (plain old data) variables in the class and similarly in a recursive fashion for any composite types the class holds.