QTcpSocket and QByteArray problem!

roteiro

Hello everybody, i have a problem with wich i struggled for the last 2-3 days. I have a simple Server application in wich i get data in a QByteArray variable i use the next line for this:

QByteArray Data = socket->readAll();

Then i output Data in hex format, to see that if what i get is the same with what the client sends me for this i do this:

qDebug() << " Data in: " << Data.toHex();

The output is this:

"a55a55aa010000000000000064000000028d0000b63d795100000000410100000000db6900000000000000000000000000000000000000008e00040000000000000000000003000000000300000000000001"

It's exactly what i was expecting, so far so good, somewhere in this string i have three bytes wich gives me local time in UTC format starting from position 20 these are the values that i need: 63d795. So i figure that in order to acces those variables i'll do this
utcTime = Data [23]
utcTime = utcTime << 8;
utcTime = utcTime + Data [22];
utcTime = utcTime << 8;
utcTime = utcTime + Data [21];
utcTime = utcTime << 8;
utcTime = utcTime + Data [20];

then i do this in order to format the date and time

QDateTime localTime(QDate(), QTime(), Qt::UTC);
localTime.setTime_t(abs(tempUtcTime));
qDebug() << localTime;

The clock shows the correct time at some point but when the third member respectivley Data [20] reaches 128 (0x80) it then changes the sign and starts counting -127...-126.....when it reaches 0 it works normally untill again reaches 128. I'm really blocked, i don't know what to do further please help me

raven-worx

is client and server written in Qt?

roteiro

No the client is something else CodeSys is an industrial programming language or something like that ..., the server is written in Qt

SGaist

Hi and welcome do DevNet,

QByteArray has it names indicates work with byte. Signed bytes go from -127 to 128.

You have to parse your byte array differently or send your data in a more practical format.

roteiro

I know, but i don't really know how to do the parsing another way, thank you

SGaist

Could you show us the exact format of your data ? I mean, what the server sends and what value is it supposed to be.

roteiro

This is my function:
@void MyThread::readyRead()
{
quint32 utcTime;

QByteArray Data = socket->readAll();
QByteArray stringDataOra;
qDebug() << " Data in: " << Data.toHex();


utcTime = Data[23];
utcTime = (utcTime << 8);
utcTime = utcTime + Data[22];
utcTime = (utcTime << 8);
utcTime = utcTime + Data[21];
utcTime = (utcTime << 8);
utcTime = utcTime + Data[20];

QDateTime localTime(QDate(), QTime(), Qt::UTC);
localTime.setTime_t(abs(tempUtcTime));
qDebug() << localTime;

}@

This is the QByteArray:
"a55a55aa010000000000000064000000028d0000b63d795100000000410100000000db6900000000000000000000000000000000000000008e00040000000000000000000003000000000300000000000001"

and from this array i try to extract the bolded bytes

but in reverse order 51793db6

SGaist

That i understood, what I want to know is: what does 51793db6 represent ? The time as in hh.MM.ss.zzz ? A time in seconds or milliseconds ? Others ?

roteiro

Exactly represents the time given in seconds in UTC format yyyy.mm.dd hh:mm:ss

roteiro

The output was this "Thu Apr 25 14:27:22 2013" it incraments the seconds correct till a point respectivly Data [20] becomes 128 then the seconds start to decrement till Data [20] is 0 again, then it upgrades the time...and start working normally and so on...

SGaist

In that case:
Why not use "QByteArray::mid":http://qt-project.org/doc/qt-4.8/qbytearray.html#mid to retrieve the value then "QByteArray::toInt":http://qt-project.org/doc/qt-4.8/qbytearray.html#toInt to have it as an int and finally "QDateTime::formTime_t":http://qt-project.org/doc/qt-4.8/qdatetime.html#fromTime_t ? to make your local time ?