QVector<float> to QByteArray without programming

[SixDegrees]

You can just take the address of the first member, assuming QVectors work like C++ vectors:

char* c = &(myVector[0]);

This assumes, though, that QVector behaves in such a way that doing so makes sense. It may not. If it doesn't behave itself, you'll have to loop through the array and do something similar to the above with each element.