CODEWITHSUNDEEP
c++qt
tonnot
tonnot

Reputation: 455

Is it impossible to write 4 bytes for a float and 8 for double at QdataStream ?

I need (I must) to write a lot of floats to a qdatastream and it is neccesary I use only 4 bytes. setFloatingPointPrecision or writes 4 or 8 both for floats and doubles. I thought that it was applicable to qreal, but I surprise it works on float a double type..

Is there any solution ? Thanks

Upvotes: 1

Views: 3730

Answers (2)

pnezis
pnezis

Reputation: 12321

A possible workaround is to write a function and overload it:

void writeReal(QDataStream& out, float f)
{
    out.setFloatingPointPrecision(QDataStream::SinglePrecision);
    out << f;
}

void writeReal(QDataStream& out, double f)
{
    out.setFloatingPointPrecision(QDataStream::DoublePrecision);
    out << f;
}

Now simply use this function for serializing floats and doubles

QFile file("file.dat");
file.open(QIODevice::WriteOnly);
QDataStream out(&file); 
writeReal(out, (float) 3.14);  // Casting to float so single precision will be used
writeReal(out, (double) 3.14); // Casting to double so double precision will be used

Upvotes: 6

Mark B
Mark B

Reputation: 96241

If you want to write only four bytes, have you considered static_casting your doubles to float? I'm not sure what a qdatastream but that might work for you.

Upvotes: 0

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