C++中友元函数

class Person
{
public:
	friend class A;
private:
	int i = 1;
};

class A
{
public:
	Person p;
	void Say()
	{
		cout << p.i << endl;
	}
};


int main()
{
	A a;
	a.Say();
}

https://www.runoob.com/cplusplus/cpp-friend-functions.html

友元函数：

class Person
{
public:
	friend void Print(Person& p);
private:
	int i = 1;
};

void Print(Person& p)
{
	cout << p.i << endl;
}

int main()
{
	Person p;
	Print(p);
}

友元函数并不是成员函数