text: // Box.h in Ex9_06
  #pragma once
  #include <iostream>
  using std::cout;
  using std::endl;
  
  class CBox                             // Base class
  {
    public:
  
      // Function to show the volume of an object
      void ShowVolume() const
      {
        cout << endl
             << "CBox usable volume is " << Volume(); 
      }
  
      // Function to calculate the volume of a CBox object
      double Volume() const
      { return m_Length*m_Width*m_Height; }
  
      // Constructor
      CBox(double lv = 1.0, double wv = 1.0, double hv = 1.0)
                              :m_Length(lv), m_Width(wv), m_Height(hv) {}
  
    protected:
      double m_Length;
      double m_Width;
      double m_Height;
  };
  