Tutorials

A friend function of class defined outside that class scope but it has a right to access all private and protected member of class. Even through prototype of a function appears in the class definition. Friend function is not member function.

A friend function can be a function, Function template or member function or a class or class template. In this case the entire class & all its members are friends. To declare a function as a friend of class, preceded function prototype in the class definition with keyword friend as follows:

e.g:

#include<iostream.h>
#include<conio.h>
class Sample{
  int x,y;
  public:
	 Sample(int i,int j){
	  x=i;
	  y=j;
	 }
	 void show(){
	  cout<<"\nx = "<<x<<"\t"<<"y = "<<y;
	 }
	 friend float avg(Sample &s);

};
float avg(Sample &s){
  return((s.x+s.y)/2.0);
}
void main()
{
 Sample s(10,4);
 clrscr();
 s.show();
 float a=avg(s);
 cout<<"\nAverage = "<<a;
 getch();
}

O/P

X=10
Y=4
Average=12