Type conversion c++, quadmath

Question

The quadmath library does not have much documentation online and I would like to perform two simple actions using __complex128 type.

• Is there a way to easily print the value inside a variable of this type?
• How can I convert back a variable from __complex128 to complex<double>, or even the single __float128 real and imaginary parts to double?

The second question is more important because if I can convert it I can simply use cout!

EDIT: Everything comes to the following question. How do I convert __float128 to double?

Answer 1

Converting a __float128 to a double does not require anything special:

const __float128 x{};
const double y = x;

You might want a static_cast for clarity (and less warnings).

Constructing a std::complex<T> from __complex128 is also not difficult:

auto bar(__complex128 y)
{
    return std::complex<double>{
        static_cast<double>(__real__ y),
        static_cast<double>(__imag__ y)
    };
}