Appending quint16 to QByteArray

mulfycrowh

Hi,

I would like to append a quint16 variable to a QByteArray to write to a file.
A quint16 is made of 2 bytes, right ?
So I wrote:

QByteArray qbatow;
...
quint16 towrite = 256;
qbatow = qbatow.append(towrite);

The trouble is in the file: I always get 1 byte only in the file instead 2 bytes. I get the LSB, that's to say 00.

Any idea ?

Thanks

kshegunov

@mulfycrowh

QByteArray qbatow;

QDataStream out(&qbatow, QIODevice::WriteOnly | QIODevice::Append);
out.setByteOrder(QDataStream::BigEndian);

quint16 towrite = 256;
out << towrite;

mulfycrowh

No ! I don't want to use the operator <<. I use writeRawData

mulfycrowh

I found the solution :

	quint16 towrite = 256;
	char* charToWrite = (char*)&towrite;
	qbatow = qbatow.append(charToWrite, sizeof(quint16));

	out.writeRawData(qbatow.data(), qbatow.length());

It's OK in the file : 00 01

kuzulis

It is better to use '<<' operator with QDataStream. Just configure QDataStream with desired BigEndian/LowEndian.

mulfycrowh

No it is not better. First of all, I used << and I didn't get the right count of bytes because depending of serialization. It's better to use writeRawData for my purpose.

kshegunov

@mulfycrowh

No it is not better.

Yes, it is, you just don't realize it yet. Run your program on Intel and on PowerPC and compare the data you get in the byte array.

First of all, I used << and I didn't get the right count of bytes because depending of serialization.

Then you did something wrong.

It's better to use writeRawData for my purpose.

I don't know what exactly is your purpose, but I really, really doubt writeRawData is better.