C++ Program to Add Two Numbers using Friend Function

#include<iostream.h>
#include<conio.h>
using namespace std;
class temp 
{
  int a, b, add;
  public:
  void input() 
{
  cout << "Enter the value of x and y:";
  cin >> x>>y;
 }
  friend void add(temp &t);
  void display() 
 {
   cout << "The sum is :" << z;
 }
};
  void add(temp &t) 
{
   t.add = t.a + t.b;
}
  int main() 
{
   temp t1;
   t1.input();
   add(t1);
   t1.display();
   return 0;
}

Output:

Enter the value of x and y: 25 20
The sum is : 45