Casting QVector<int> to QVector<double>

dovahin

Is there an elegant way of casting QVector<int> to QVector<double> ? I know I could iterate through both of them, but looking for something better

SGaist

Hi and welcome to devnet,

Why do you need to do that for ?

kshegunov

@dovahin said in Casting QVector<int> to QVector<double>:

I know I could iterate through both of them, but looking for something better

What @SGaist wrote. Also there's nothing better. QVector<int> and QVector<double> are two different and distinct classes, you can't just cast from one to the other.

dovahin

@SGaist because I have QVector<int> and I need to pass it to qwt_plot_currve function setSamples which takes QVector<double>

jsulm

@dovahin Either you use QVector<double> from the beginning, then there is no need to cast anything. Or you will have to iterate over the element of your QVector<int> and add each element to the QVector<double> which isn't efficient.
As @kshegunov said both classes are different and you can't simply cast one to the other.

J.Hilk

@dovahin

you could try to initialize your QVectpr<double>(myOtherVector.size()) and than try direct data manipulation via T *QVector::data() but you can not simply memcopy the data over. It won't be the same size and is not reinterpret_cast compatible.

Christian Ehrlicher

The propose idea to use QVector<double> in the first place is the fastest one. But if you really need to convert such a vector:

QVector<int> in;
QVector<double> out;
out.reserve(in.size());
std::copy(in.cbegin(), in.cend(), std::back_inserter(out));

dovahin

@Christian-Ehrlicher thanks, thats solve my problem :)