C++ Program to implement friend class and friend functions :

Friendclass.cpp

    #include<iostream>
    #include<string>
    using namespace std;
    class second{
        private:
            string a,b;
        public:
            second(string x,string y);
        friend class first;
    };
    class first{
        public:
            void firstname(second);
            void secondname(second);
    };
    second::second(string x,string y){
        a=x;
        b=y;
    }
    void first::firstname(second s){
        cout<<"\nYour first name is "<<s.a<<endl;
    }
    void first::secondname(second s){
        cout<<"\nYour second name is "<<s.b<<endl;
    }
    int main()
    {
        string a,b;
        cout<<"Enter your Name : ( First Name followed by second Name )\n";
        cin>>a>>b;
        second obj(a,b);
        first temp;
        temp.firstname(obj);
        temp.secondname(obj);
        return 0;
    }