my C++ rough work

// Testing friend function


#include

class sum
{
private:
int i;
friend void square(sum s);
sum()
{
i = 1;
}
public:
sum(int j)
{
i = j;
}

void get()
{
cout << i;
}

};

void square(sum s)
{
s.i = s.i*s.i;
cout << s.i;
}
int main(){
sum s(3);

square(s);
s.get();
}