Answer to Question #261722 in C++ for Rohit Swain

Question

1) Write a C++ Program to swap data members of two objects of a class using friend function.

2)Write a C++ program to demonstrate friend class.

Answer 1

SOLUTION TO THE ABOVE QUESTION

part 1.

1) Write a C++ Program to swap data members of two objects of a class using friend function.

SOLUTION CODE

#include <iostream> 
//forward declaration 
class myclass_for_object_2;
class myclass_for_object_1 
{ 
    public: 
    int get(){return a;} 
    private: 
    int a=456; 
    friend void swap(myclass_for_object_1 &myclass_for_object_1, myclass_for_object_2 &myclass_for_object_2); 
 
}; 
class myclass_for_object_2 
{ 
    public: 
    int get(){return a;} 
    private: 
    int a=654; 
     friend void swap(myclass_for_object_1 &myclass_for_object_1, myclass_for_object_2 &myclass_for_object_2); 
}; 
 
void swap(myclass_for_object_1 &myclass_for_object_1, myclass_for_object_2 &myclass_for_object_2) 
{ 
    int a = myclass_for_object_1.a; 
    myclass_for_object_1.a=myclass_for_object_2.a; 
    myclass_for_object_2.a=a; 
} 
 
int main() 
{ 
myclass_for_object_1 f ; 
myclass_for_object_2 s ; 
std::cout<<f.get()<<' '<<s.get()<<std::endl; 
swap(f,s); 
std::cout<<f.get()<<' '<<s.get()<<std::endl; 
return 0; 
} 

SAMPLE PROGRAM OUTPUT

part 2

2)Write a C++ program to demonstrate friend class.

SOLUTION CODE

#include <iostream>
class my_class {
private:
	int variable_1;


public:
	my_class() { variable_1 = 20; }
	friend class friend_to_my_cclass; // Friend Class
};


class friend_to_my_cclass {
private:
	int variable_2;


public:
	void show_method(my_class& value)
	{
		// Since friend_to_my_cclass is friend of my_class, it can access
		// private members of my_class
		std::cout << "My_class::variable_1=" << value.variable_1;
	}
};


int main()
{
	my_class variable_1;
	friend_to_my_cclass variable_2;
	variable_2.show_method(variable_1);
	return 0;
}

SAMPLE PROGRAM OUTPUT