Friend Classes in C++ ( Multiple classes ) | Mohd Abuzar

 

Friend Classes  :  As you are all know that friend function can access the private  and protected data which is declare as a friend . It is sometime to useful the particular classes to access the private member of another class .

Friend Function :  Like a friend class , friend function can be access the grant to access the private and protected data member . It is same as a friend function .

a ) A member of another class

b) A global function 

In a program , we are all know that we can't access the private and protected data member so in c++ friend function is a type of function which can access the private and protected data member and the friend function make the outside the class . But friend function is not same as inheritance .

Example of Friend Classes 

A complete C++ program to demonstrate friend function of another class .

#include <iostream>

class A { private:

    int a;

public:

   A() { a = 0; }

    friend class B; // Friend Class };

class

B {

private:

    int b;

public:

    void showA(A& x)

    { // Since B is friend of A, it can access

 // private members of A

 std::cout << "A::a=" << x.a;

    } };

int main()

{

A a ;

    B b;

    b.showA(a);

    return 0;

}

   Output : 

      A::a=0

 

    A complete C++ program to demonstrate global function .

#include <iostream>

 

class A {

  int a;

public:

  A() { a = 0; }

  // global friend function

friend void showA(A&); };

void showA(A& x)

{

// Since showA() is a friend, it can access

 // private members of A

  std::cout << "A::a=" << x.a;

}

int main()

{

    A a;

 showA(a);

return 0; }




  Output : 

      A::a=0

References : 

https://en.wikipedia.org/wiki/Friend_class

https://en.wikipedia.org/wiki/Friend_function

Please write comment if you find anything incorrect in the above information .

This article is contributed by Mohd Abuzar . If you like code with abuzar  or want to share more information about this topic so you will be mail at abuzar.abuzar.mohd325@gmail.com 

RECOMMENDED ARTICLES 

1. Friend function in C++ 
2. Inline Function in C++ 
3. Object Orientend programming in C++