C++ program to demonstrate friend function

#include <iostream>
using namespace std;
class B;
class A
{
private:
int a;
public:
void inputdata()
{
cout<<"Enter a....";
cin>>a;
}
friend int sum(A objA,B objB);
};
class B
{
private:
int b;
public:
void inputdata()
{
cout<<"Enter b....";
cin>>b;
}
friend int sum(A objA,B objB);
};
int sum(A objA,B objB)
{
int s=objA.a+objB.b;
return s;
}
int main()
{
A objA;
B objB;
int n;
objA.inputdata();
objB.inputdata();
n=sum(objA,objB);
cout<<"Sum is...."<<n<<endl;
return 0;
}