C++ Friend Function

C++ Friend function is a function that is not a member of a class, even than it can access to the class's private, protected, and public members. Friend function works like a normal function. Friend function are not called using the member operators (. and ->). To declare a friend function, define its prototype within the class public section, preceding it with the friend keyword.

Example 1: Friend function. 1

#include <iostream.h>
#include <conio.h>
//friend function

class A{
    int a;
public:
    void input1();
    void output1();
    friend void fun(A obj2);
};
void A::input1()
{
    cout<<"Enter no";
    cin>>a;
}
void A::output1()
{
    cout<<"Class A Output1"<<a;
}
void fun(A obj2)
{
    cout<<"\nNormal function"<<obj2.a;
}
void main()
{
    A obj;
    clrscr();
    obj.input1();
    obj.output1();
    fun(obj);
    getch();
}

C++ Friend Class

It is possible for one class to be a friend of another class. In CPP, member functions of friend class can access to the private, public members defined within other class.

Example 2: Friend class. 1

#include <iostream.h>
#include <conio.h>

class A
{
    int a;
    public:
      void input1();
      void output1();
      friend class B;
};
void A::input1()
{
    cout<<"Enter no";
    cin>>a;
}
void A::output1()
{
    cout<<"Class A Output 1";
}

class B{
    int b;
    public:
      void output2(A);
};
void B::output2(A obj1)
{
    cout<<"Class B Output 2: " <<obj1.a;
}

void main()
{
    A obj1;
    clrscr();
    obj1.input1();
    B obj2;
    obj2.output2(obj1);
    getch();
}

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