Friend function in c++ | Friend fuctions class in c++

 

#include<iostream>

using namespace std;

class c2;

class c1{

    int val1;

    friend void exchange(c1 &,c2 &);

    public:

        void inData(int a)

        {

            val1=a;

        }

        void display(){

            cout<<"The value of c1 is "<<val1<<endl;

        }

};

class c2{

    int val2;

    friend void exchange(c1 &,c2 &);

    public:

        void inData(int a)

        {

            val2=a;

        }

        void display(){

            cout<<"The value of c1 is "<<val2<<endl;

        }

};

void exchange(c1 & x,c2 & y)

{

    int tem;

    tem=x.val1;

    x.val1=y.val2;

    y.val2=tem;

}

int main()

{

    c1 oc1;

    c2 oc2;

    oc1.inData(34);

    oc2.inData(88);

    cout<<"Before Exchange"<<endl;

    cout<<"c1 :";

    oc1.display();   

    cout<<"c2 :";

    oc2.display();

    cout<<endl; 

    exchange(oc1,oc2);

    cout<<"After Exchange"<<endl;

    cout<<"c1 :";

    oc1.display();   

    cout<<"c2 :";

    oc2.display();

    cout<<endl;   

    return 0;

}