ex8_12.cpp

Beginning Visual C++ 6源码。Wrox。

// EX8_12.CPP
// Exercising the indirect member access operator
#include <iostream>
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;
      }

      // Function to compare two boxes which returns true (1)
      // if the first is greater that the second, and false (0)          
      // otherwise
      int Compare(CBox* pBox) const
      {
         return this->Volume() > pBox->Volume();
      }

   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
};

int main()
{
   CBox boxes[5];                    // Array of CBox objects declared
   CBox match(2.2, 1.1, 0.5);        // Declare match box
   CBox cigar(8.0, 5.0, 1.0);        // Declare cigar Box
   CBox* pB1 = &cigar;               // Initialize pointer to cigar object 
							// address
   CBox* pB2 = 0;                    // Pointer to CBox initialized to null

   cout << endl 
        << "Address of cigar is " << pB1             // Display address
        << endl
        << "Volume of cigar is " << pB1->Volume();   // Volume of object
                                                     // pointed to

   pB2 = &match;
   if(pB2->Compare(pB1))              // Compare via pointers
      cout << endl
           << "match is greater than cigar";
   else
      cout << endl
           << "match is less than or equal to cigar";

   pB1 = boxes;                                      // Set to address of array
   boxes[2] = match;                                 // Set 3rd element to match
   cout << endl                                      // Now access thru pointer
        << "Volume of boxes[2] is " << (pB1 + 2)->Volume();

   cout << endl;
   return 0;
}