fig10_16.cpp

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

// 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

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