Friend functions can access private members of a class : friend function « Class « C++ Tutorial

1. C++ Tutorial
2. Class
3. friend function

#include <iostream>
using std::cout;
using std::endl;

class MyClass 
{
   friend void setX( MyClass &, int ); // friend declaration
public:
   MyClass() : x( 0 )
   { 
   }
   void print() const       
   { 
      cout << x << endl; 
   }
private:
   int x;
};
void setX( MyClass &c, int val )
{
   c.x = val;
} 

int main()
{
   MyClass counter;
   counter.print();

   setX( counter, 8 );
   counter.print();
   return 0;
}

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