fig10_16.cpp

来自「是有关C++编程原理教程的例子程序,全,应该对大家有所帮助」· C++ 代码 · 共 56 行

// Fig. 10.16: fig10_16.cpp 
// Non-friend/non-member functions cannot access private data of a class.
#include <iostream>
using std::cout;
using std::endl;

// Count class definition (note that there is no friendship declaration)
class Count 
{
public:
   // constructor
   Count() 
      : x( 0 ) // initialize x to 0
   { 
      // empty body
   } // end constructor Count

   // output x 
   void print() const       
   { 
      cout << x << endl; 
   } // end function print
private:
   int x; // data member
}; // end class Count

// function cannotSetX tries to modify private data of Count,
// but cannot because the function is not a friend of Count
void cannotSetX( Count &c, int val )
{
   c.x = val; // ERROR: cannot access private member in Count
} // end function cannotSetX

int main()
{
   Count counter; // create Count object

   cannotSetX( counter, 3 ); // cannotSetX is not a friend
   return 0;
} // end main

/**************************************************************************
 * (C) Copyright 1992-2005 by Deitel & Associates, Inc. and               *
 * Pearson Education, Inc. All Rights Reserved.                           *
 *                                                                        *
 * DISCLAIMER: The authors and publisher of this book have used their     *
 * best efforts in preparing the book. These efforts include the          *
 * development, research, and testing of the theories and programs        *
 * to determine their effectiveness. The authors and publisher make       *
 * no warranty of any kind, expressed or implied, with regard to these    *
 * programs or to the documentation contained in these books. The authors *
 * and publisher shall not be liable in any event for incidental or       *
 * consequential damages in connection with, or arising out of, the       *
 * furnishing, performance, or use of these programs.                     *
 **************************************************************************/