friendFunction.cpp

#include <iostream>
using namespace std;

class sample
{
    int a;
    int b;

public:
    void setvalue()
    {
        a = 25;
        b = 40;
    }
    friend float mean(sample s);
};

float mean(sample s)
{
    return static_cast<float>(s.a + s.b) / 2;
}

int main()
{
    sample x;
    x.setvalue();
    cout << "Mean value : " << mean(x) << "\n";
    return 0;
}