QRandomGenerator ULLONG_MAX

[Redman]

Hello,

generating a random integer between 0 and ULONGLONG_MAX does not work.

QRandomGenerator rng;
//works
   quint16 x = rng.bounded(0, USHRT_MAX);
   QByteArray xHex = QString::number(x, 16).toUpper().toLocal8Bit();


// does not work
   quint64 y = rng.bounded(quint64(0), quint64(18446744073709551615));
   quint64 y = rng.bounded(quint64(0), ULLONG_MAX);
   quint64 y = rng.bounded(0, ULLONG_MAX);
   QByteArray yHex = QString::number(y, 16).toUpper().toLocal8Bit();


// works
   quint16 z = rng.bounded(0, USHRT_MAX);
   QByteArray zHex = QString::number(z, 16).toUpper().toLocal8Bit();

Anyone know how to make this work?

[Christian Ehrlicher]

And you should also read the documentation carefully:

"Note that this function cannot be used to obtain values in the full 64-bit range of quint64. Instead, use generate64()."

[Christian Ehrlicher]

@Redman said in QRandomGenerator ULLONG_MAX:

does not work.

Apart fromt he fact that the code does not compile this is not an useful error description...

[JonB]

@Redman
In what sense "does not work"? Generates a compilation error? Does not return what you expect it to at runtime?

I was not able to find ULONGLONG_MAX (other than in Boost). Your code does not use such a symbol. ULLONG_MAX does exist and seems to be "unsigned long long int", 64-bit. The (only) overload I see matching this is quint64 QRandomGenerator::bounded(unsigned int lowest, quint64 highest). Make sure you use this overload. I don't see any overload which takes quint64 for both lower & upper bounds. quint64 y = rng.bounded(0, ULLONG_MAX); looks like it should match, try static_cast<>ing the parameters to make sure this one is being used?

[Christian Ehrlicher]

And you should also read the documentation carefully:

"Note that this function cannot be used to obtain values in the full 64-bit range of quint64. Instead, use generate64()."

[Redman]

@JonB rng.bounded(unsigned int(0), ULLONG_MAX); compiles successfully. There is aproblem in qrandomh.h inline quint64 QRandomGenerator::bounded(quint64 highest) with the mask.

But as Christian pointed out, the function is not suited for my usecase. Thanks