<![CDATA[QDataStream default LittleEndian]]>Hi,
till today, use QDatastream was not a problem, it writes data in BigEndian by default.
But I want to create a binary file and Qt write it in LittleEndian format. And if I force it with setByteOrder(QDataStream::BigEndian), it keeps LittleEndian format.

Someone has already this problem ?

QFile f("D:/Temp/camera.dat");
f.open(QIODevice::WriteOnly);
QDataStream str(&f);
str.setByteOrder(QDataStream::BigEndian);
int test = 1080;
str.writeRawData(reinterpret_cast<char*>(&test), sizeof(int));
f.close();

I use W11 and Qt 6.4.2

Thanks

]]>https://forum.qt.io/topic/146042/qdatastream-default-littleendianRSS for NodeWed, 04 Nov 2026 19:09:36 GMTTue, 27 Jun 2023 14:12:00 GMT60<![CDATA[Reply to QDataStream default LittleEndian on Tue, 27 Jun 2023 14:19:22 GMT]]>@OPit said in QDataStream default LittleEndian:

str.writeRawData(reinterpret_cast<char*>(&test), sizeof(int));

Why don't you do instead:

str << test;

?
There is no byte order for a byte array.

]]>https://forum.qt.io/post/762755https://forum.qt.io/post/762755Tue, 27 Jun 2023 14:19:22 GMT<![CDATA[Reply to QDataStream default LittleEndian on Wed, 28 Jun 2023 05:10:46 GMT]]>@OPit said in QDataStream default LittleEndian:

why LittleEndian is always used with writeRawData

Because writeRawData writes a bunch of bytes and byte order is not relevant for it. Byte order is only relevant for things like integers, floats, ... (for data types bigger than one byte).

]]>https://forum.qt.io/post/762814https://forum.qt.io/post/762814Wed, 28 Jun 2023 05:10:46 GMT<![CDATA[Reply to QDataStream default LittleEndian on Tue, 27 Jun 2023 15:27:23 GMT]]>@jsulm Oh thank you. I believed Qt was adding pseudo data when use << .

Perfect, it's resolved (even if I don't know why LittleEndian is always used with writeRawData)

]]>https://forum.qt.io/post/762766https://forum.qt.io/post/762766Tue, 27 Jun 2023 15:27:23 GMT<![CDATA[Reply to QDataStream default LittleEndian on Tue, 27 Jun 2023 14:19:22 GMT]]>@OPit said in QDataStream default LittleEndian:

str.writeRawData(reinterpret_cast<char*>(&test), sizeof(int));

Why don't you do instead:

str << test;

?
There is no byte order for a byte array.

]]>https://forum.qt.io/post/762755https://forum.qt.io/post/762755Tue, 27 Jun 2023 14:19:22 GMT