Создать 1 базовый класс и несколько производных

#include <iostream>
#include <sstream>
#include <stdexcept>
#include <string>
 
class Point1D {
public:
  Point1D(double x)
      : m_x(x)
  {
  }
 
  double getX() const { return m_x; }
 
  virtual double get(size_t i) const;
 
  virtual size_t size() const;
 
private:
  double m_x;
};
 
double Point1D::get(size_t i) const
{
  switch (i) {
  case 0:
    return getX();
  default:
    throw std::out_of_range("Point1D have only 1 dimensions");
  }
}
 
size_t Point1D::size() const { return 1u; }
 
 
 
class Point2D : public Point1D {
public:
  Point2D(double x, double y)
      : Point1D(x)
      , m_y(y)
  {
  }
 
  double getY() const { return m_y; }
 
  virtual double get(size_t i) const;
 
  virtual size_t size() const;
 
private:
  double m_y;
};
 
double Point2D::get(size_t i) const
{
  switch (i) {
  case 0:
    return getX();
  case 1:
    return getY();
  default:
    throw std::out_of_range("Point2D have only 2 dimensions");
  }
}
 
size_t Point2D::size() const { return 2u; }
 
 
 
class Point3D : public Point2D {
public:
  Point3D(double x, double y, double z)
      : Point2D(x, y)
      , m_z(z)
  {
  }
 
  double getZ() const { return m_z; }
 
  virtual double get(size_t i) const;
 
  virtual size_t size() const;
 
private:
  double m_z;
};
 
double Point3D::get(size_t i) const
{
  switch (i) {
  case 0:
    return getX();
  case 1:
    return getY();
  case 2:
    return getZ();
  default:
    throw std::out_of_range("Point3D have only 3 dimensions");
  }
}
 
size_t Point3D::size() const { return 3u; }
 
 
 
std::string toString(const Point1D &point)
{
  std::stringstream ss;
  ss << "(" << point.get(0);
  for (size_t i = 1; i < point.size(); ++i) {
    ss << ", " << point.get(i);
  }
  ss << ")";
  return ss.str();
}
 
Point1D readPoint1D()
{
  std::cout << "Input Point1D: ";
  double x;
  std::cin >> x;
  return Point1D(x);
}
 
int main()
{
  Point1D p1(1.1);
  Point2D p2(1.2, 2.2);
  Point3D p3(1.3, 2.3, 3.3);
 
  std::cout << "p1: " << toString(p1) << "\n";
  std::cout << "p2: " << toString(p2) << "\n";
  std::cout << "p3: " << toString(p3) << "\n";
 
  Point1D p4 = readPoint1D();
  std::cout << "p4: " << toString(p4) << "\n";
 
  return 0;
}