友元类使用方法

#include <iostream>

using namespace std;

class Ctmp {
        public:
                Ctmp();
                friend class COut;
        private:
                int priv;
};

class COut {
        public:
                void output(Ctmp &);
};

Ctmp::Ctmp()
{
        priv = 24;
}

void COut::output(Ctmp &t)
{
        cout << t.priv << endl;
}

int main(void)
{
        Ctmp t;

        COut out;

        out.output(t);

        return 0;
}