Error C2662， cannot convert ‘this’ pointer from ‘const class ’ to ‘class &’
classPoint3d{public:Point3d(floatx=0.0,floaty=0.0,floatz=0.0):_x(x),_y(y),_z(z){}floatGetX(){return_x;}floatGetY(){return_y;}floatGetZ(){return_z;}private:float_x,_y,_z;};inlineostream&operator<<(ostr