Write a C++ program to demonstrate the use of Friend function in class
Assignment 13
Write a C++ program to demonstrate the use of Friend function in class.
: Example 1 :
Program Code with explanation:
1.
#include <iostream>
2.
using namespace std;
3.
class Demo
4.
{
5.
int n1;
6.
public:
7.
friend
int DemoFriend(Demo); //friend function
8.
};
9.
int DemoFriend(Demo b)
10. {
11. b.n1
= 100;
12. return
b.n1;
13. }
14. int main()
15. {
16. Demo
b;
17. cout
<< " Value of n1 of Class Demo: " << DemoFriend(b) <<
endl;
18. return
0;
19. }
Explanation of Code:
Syntax of Friend function:
friend return_data_type function_name(list of arguments);
Example:
friend int DemoFriend(Demo object);
Define the friend function outside the class scope so friend
function called as normal function.
It permits to access private and protected member of class.
It access the member using object name.
We pass the object of class as a parameter to friend function
for access member of class in friend function.
Program Code for run:
#include
<iostream>
using
namespace std;
class
Demo
{
int n1;
public:
friend int DemoFriend(Demo); //friend
function
};
int
DemoFriend(Demo b)
{
b.n1 = 100;
return b.n1;
}
int
main()
{
Demo b;
cout << " Value of n1 of
Class Demo: " << DemoFriend(b)
<< endl;
return 0;
}
Output of Program:
Value of n1 of Class Demo: 100
: Example 2 :
Program Code with explanation:
1.
#include <iostream>
2.
using namespace std;
3.
class Demo_B; // Declarartion of class Demo_B.
4.
class Demo_A
5.
{
6.
int
a;
7.
public:
8.
void
accept(int i)
9.
{
10. a
= i;
11. }
12. friend
void min(Demo_A,Demo_B);
13. //
friend function decleration.
14. };
15. class Demo_B
16. {
17. int
b;
18. public:
19. void
accept(int i)
20. {
21. b
= i;
22. }
23. friend
void min(Demo_A,Demo_B);
24. //
friend function decleration.
25. };
26. void min(Demo_A a1,Demo_B b1)
27. {
28. cout
<< " Minimum Value from member of class";
29. cout
<< " Demo_A and Demo_B : ";
30. if(a1.a
<= b1.b)
31. cout
<< a1.a << endl;
32. else
33. cout
<< b1.b << endl;
34. }
35. int main()
36. {
37. Demo_A
a;
38. Demo_B
b;
39. a.accept(10);
40. b.accept(20);
41. min(a,b);
42. return
0;
43. }
Explanation of Code:
This min friend function can access private as well as protected member of both class using corresponding class object.
We can pass object of class to friend function, Whose members want to access.
Program Code for run:
#include
<iostream>
using
namespace std;
class
Demo_B; // Declarartion of class
Demo_B.
class
Demo_A
{
int
a;
public:
void
accept(int i)
{
a
= i;
}
friend
void min(Demo_A, Demo_B);
// friend function decleration.
};
class
Demo_B
{
int
b;
public:
void
accept(int i)
{
b
= i;
}
friend
void min(Demo_A, Demo_B);
// friend function decleration.
};
void
min(Demo_A a1, Demo_B b1)
{
cout
<< " Minimum Value from member of class";
cout << " Demo_A and Demo_B :
";
if(a1.a
<= b1.b)
cout
<< a1.a << endl;
else
cout
<< b1.b << endl;
}
int
main()
{
Demo_A
a;
Demo_B
b;
a.accept(10);
b.accept(20);
min(a,b);
return
0;
}
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