Class Box

Examples/NoModules/Chapter 13/Ex13_09/Box.h:8–42

#include <format>

class Box
{
public:
  // Constructors
  Box() = default;
  Box(double l, double w, double h) : m_length{ l }, m_width{ w }, m_height{ h } {}

  Box& operator++();         // Prefix ++operator
  const Box operator++(int); // Postfix operator++
  Box& operator--();         // Prefix --operator
  const Box operator--(int); // Postfix operator--

  double volume() const { return m_length * m_width * m_height; }

  // Accessors
  double getLength() const { return m_length; }
  double getWidth()  const { return m_width; }
  double getHeight() const { return m_height; }

  std::partial_ordering operator<=>(const Box& otherBox) const 
  { 
    return volume() <=> otherBox.volume();
  }
  std::partial_ordering operator<=>(double otherVolume) const 
  { 
    return volume() <=> otherVolume;
  }

  bool operator==(const Box& otherBox) const = default;

private:
  double m_length{ 1.0 };
  double m_width{ 1.0 };
  double m_height{ 1.0 };
};

inline Box& Box::operator++()   // Prefix ++operator
{