How to convert quint64 to 4 byte QByteArray

Infinity

How can I convert a quint64 into a 4 byte QByteArray?

I have a quint64 with the value of 19

quint64 length = 19;

Note: The length could also be much larger. I have to pass it to a QTcpSocket. The protocol requires that the first 4 bytes are the size of the whole message.

The QByteArray should look like this:

\x13\x00\x00\x00\

How can I do that?

mpergand

Use a QDataStream with a QBuffer:

   QBuffer buf;
   buf.open(QBuffer::ReadWrite);
   QDataStream stream(&buf);

   qint64 v=19;
   stream<<v;
   QByteArray arr=buf.buffer();

The array looks like:
"\x00\x00\x00\x00\x00\x00\x00\x13"
By default QDataStream use big endian ( you can change to little endian)
The array is 8 bytes length (qint64=8bytes)
If you really want 4 bytes in length, you must use qint32 instead.

Infinity

@mpergand Perfect. Thank you very much.