1.友元函数

1.class

class MM {
public:MM(int age,string name):age(age),name(name){}friend void print(MM mm);
private:int age;string name;void print() {cout << age << "岁的" << name << "喜欢你" << endl;}
};

friend 函数的编写

void print(MM mm) {mm.print();//print为私有函数，函数设为友元函数时可以使用
}

2.main

int main() {MM mm(18, "女神");print(mm);return 0;
}

3.结果：

2.友元函数（这个函数是另一个类函数）

1.class

class boy {
public:static void boyLove();
};
class MM {
public:MM(int age,string name):age(age),name(name){}friend void boy::boyLove();
private:int age;string name;void print() {cout << age << "岁的" << name << "喜欢你" << endl;}
};

2.实现friend函数

void boy::boyLove() {MM mm(10, "女生");mm.print();
}

3.main

int main() {MM mm(18, "女神");boy::boyLove();return 0;
}

4.结果：