QDataStream >> uin64_t

[ikuris]

Hello, I do have a function like this

void MainWindow::bttnClc()
{
    uint64_t it3;
    QByteArray byte;
    QDataStream raw(&byte, QIODevice::ReadOnly);
    raw.setFloatingPointPrecision(QDataStream::DoublePrecision);
    raw.setByteOrder(QDataStream::ByteOrder::LittleEndian);

    raw.device()->seek(0);

    raw >> it3;

}

It is just an example but when I try to compile it on WSL2 with cmake I get the given error

error: no match for ‘operator>>’ (operand types are ‘QDataStream’ and ‘uint64_t’ {aka ‘long unsigned int’})

When I looked over it I saw there is no uint implementation of >> in QDataStream.cpp.

MY question is why is this code works on Windows and not working on Linux, How to fix this error without changing the code or do I have to change the code?

Thank you for your time.

[Christian Ehrlicher]

qglobal.h:
msvc: typedef unsigned __int64 quint64; /* 64 bit unsigned /
other: typedef unsigned long long quint64; / 64 bit unsigned */

cstdint or whereever the depths of the standard includes.
gcc: typedef unsigned long int __uint64_t;
typedef __uint64_t uint64_t;

unsigned long long != unsigned long int I would guess.

[JonB]

@ikuris
There is QDataStream &QDataStream::operator<<(quint64 i). And for uint64 https://doc.qt.io/qt-6/qtglobal.html#quint64-typedef defines

Typedef for unsigned long long int. This type is guaranteed to be 64-bit on all platforms supported by Qt.

Would have thought that would work. Might depend on compiler or platform. I note your error message says

‘uint64_t’ {aka ‘long unsigned int’}

which differs from unsigned long long int?

Is uint64_t defined in a C++ standard library? I would investigate how uint64_t is not the same as quint64. And how ‘uint64_t’ {aka ‘long unsigned int’} does not match any of the QDataStream:operator<< integer overloads? Actually, verify what happens in the WSL2 case with quint64 here?

[Christian Ehrlicher]

QDataStream has no overload for uint64_t, only for quint64.

[JonB]

@Christian-Ehrlicher
What is the typical definition for uint64_t, and where does it come from? How would it differ from quint64?

[Christian Ehrlicher]

qglobal.h:
msvc: typedef unsigned __int64 quint64; /* 64 bit unsigned /
other: typedef unsigned long long quint64; / 64 bit unsigned */

cstdint or whereever the depths of the standard includes.
gcc: typedef unsigned long int __uint64_t;
typedef __uint64_t uint64_t;

unsigned long long != unsigned long int I would guess.

[ikuris]

@JonB said in QDataStream >> uin64_t:

as quint64. And how ‘uint64_t’ {aka ‘long unsigned int’} does

uint64_t defined in <cstdint>. It does compile as expected when uint64_t becomes quint64.

[JonB]

@Christian-Ehrlicher said in QDataStream >> uin64_t:

unsigned long long != unsigned long int I would guess.

Interesting.

[ikuris]

@Christian-Ehrlicher

So this is the reason why it does compile on Windows ? Thank you.

[Christian Ehrlicher]

@ikuris said in QDataStream >> uin64_t:

So this is the reason why it does compile on Windows

Already explained:

unsigned long long != unsigned long int