友元成员函数,该如何处理

友元成员函数

C/C++ code

#include<iostream>using namespace std;class A;class B{public:    void set(A &a)    {        a.a=100;    }};class A{public:    void print()    {        cout<<a<<endl;    }    friend void B::set(A &a);private:    int a;};void main(){    A a;    B b;    b.set(a);    a.print();}

C/C++ code

#include<iostream>using namespace std;class A;class B{public:    void set(A &a);};class A{public:    void print()    {        cout<<a<<endl;    }    friend void B::set(A &a);private:    int a;};void B::set(A &a){    a.a=100;}int main(){    A a;    B b;    b.set(a);    a.print();}