Friend Class in C++ Programming


The given C++ program demonstrates the use of friend classes in C++.

  • The program starts by including the necessary header files and defining two classes A and B. Class A has a private data member x which is initialized to 10. The class A also has a friend declaration for class B.
  • Class B has a public object o of class A and a member function display(). The display() function prints the value of x of the o object of class A.
  • In the main() function, an object obj of class B is created, and the display() function of class B is called, which displays the value of x of the o object of class A.
  • Since class B is declared as a friend of class A, it has access to the private data member x of class A. This is demonstrated in the display() function of class B.
  • Friend classes are useful when we want to provide access to private members of a class to another class. In this case, class B is a friend of class A, so it has access to the private member x of class A.
  • The program ends by returning 0 from the main() function, indicating that the program ran successfully.

Source Code

#include<iostream>
using namespace std;
//Friend Class
class B;
class A
{
private:
    int x=10;
    friend B;
};
 
class B
{
public:
    A o;
    void display()
    {
        cout<<"X : "<<o.x;
    }
};
int main()
{
    B obj;
    obj.display();
    return 0;
}
 

Output

X : 10
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