来自 QtEndian 与 stdint.h 的冲突数据类型 quint16_be

Question

I want to use qint16_be, quint16_be, quint32_be etc. as a data type for big endian what I am trying is something like this

#include <QtEndian>
typedef quint16_be uint16_t;

And I am getting error

C:/Qt/5.15.2/mingw81_64/include/QtCore/qendian.h:429:28: error: conflicting declaration 'typedef QBEInteger<short int> qint16_be'
 typedef QBEInteger<qint16> qint16_be;
 C:/Qt/Tools/mingw810_64/x86_64-w64-mingw32/include/stdint.h:38:25: note: previous declaration as 'typedef short unsigned int qint16_be'
 typedef unsigned short  qint16_be;

I have not included stdint.h in my project. Any idea how would I resolve it

Answer 1

Here we go: an MCVE for qToBigEndian() :

#include <QtCore>

int main()
{
  const uint16_t sample = 0x0201;
  QByteArray data((const char*)&sample, sizeof sample);
  qDebug() << data;
  const uint16_t sampleBE = qToBigEndian(sample);
  QByteArray dataBE((const char*)&sampleBE, sizeof sampleBE);
  qDebug() << dataBE;
}

Output:

"\x01\x02"
"\x02\x01"

I ran this sample in VS2019 on my Intel laptop which has little-endian architecture.
Respectively, the byte order was changed due to the call of qToBigEndian() .

The conversion to QByteArray was a quick hack.
Nevertheless, conversion of const uint16_t* to const char* is allowed (with the intention to get access to the byte representation of something).

memcpy() is another permitted way to achieve this.