Inquiry about class variable declarations in C++

Question

I have a class to represent a 3D vector of floats:

class Vector3D
{
    public:

    float x, y, z;
    float * const data;

    Vector3D() : x(0.0), y(0.0),         


        

Answer 1

or you can have an operator[] overload

float operator[](int idx)
{
 switch (idx)
{
case 0:
  return x;
case 1:
  return y;
case 2:
 return z;
}
assert (false);
}