ex9_03.cpp

Beginning Visual C++ 6源码。Wrox。

//EX9_03.CPP
// Exercising the overloaded 'greater than' operator
#include <iostream>                      // For stream I/O
using namespace std;

class CBox                               // Class definition at global scope
{
   public:
      // Constructor definition
      CBox(double lv = 1.0, double bv = 1.0, double hv = 1.0):
           m_Length(lv), m_Breadth(bv), m_Height(hv)
      {
         cout << endl << "Constructor called.";
      }

      // Function to calculate the volume of a box
      double Volume() const
      {
         return m_Length*m_Breadth*m_Height;
      }

      bool operator>(const CBox& aBox) const;  // Overloaded 'greater than'

      // Destructor definition
      ~CBox()
      { cout << "Destructor called." << endl; }

   private:
      double m_Length;                         // Length of a box in inches
      double m_Breadth;                        // Breadth of a box in inches
      double m_Height;                         // Height of a box in inches
};

// Operator function for 'greater than' that
// compares volumes of CBox objects.
bool CBox::operator>(const CBox& aBox) const
{
   return this->Volume() > aBox.Volume();
}

int main()
{
   CBox smallBox(4.0, 2.0, 1.0);
   CBox mediumBox(10.0, 4.0, 2.0);
   CBox bigBox(30.0, 20.0, 40.0);

   if(mediumBox > smallBox)
      cout << endl
           << "mediumBox is bigger than smallBox";

   if(mediumBox > bigBox)
      cout << endl
           << "mediumBox is bigger than bigBox";
   else
      cout << endl
           << "mediumBox is not bigger than bigBox";

   cout << endl;
   return 0;
}