《C++》友元

友元--friend

友元可以访问类的私有属性

class Person
{
	friend void test();

public:
	Person(int n)
	{
		this->n = n;
	}

private:
	int n;
};
void test()
{
	Person p(20);
	cout << p.n << endl;
}
int main()
{
	test();
	system("pause");
	return 0;
}

友元可以是友类、友函数、成员函数

重载运算符--operator

#include <iostream>
using namespace std;

class Person
{
	friend void test();
	friend Person operator+(Person &p1, Person p2);

public:
	Person(){};
	Person(int a,int b)
	{
		m_a = a;
		m_b = b;
	}
private:
	int m_a;
	int m_b;
};
Person operator+(Person &p1, Person p2)
{
	Person tmp ;
	tmp.m_a = p1.m_a + p2.m_a;
	tmp.m_b = p1.m_b+ p2.m_b;
	return tmp;
}
void test()
{
	Person p1(10, 10);
	Person p2(20, 20);
	Person p3 = p1 + p2;
	cout << "p3.m_a= " << p3.m_a << "p3.m_b= " << p3.m_b << endl;
}
int main()
{
	test();
	system("pause");
	return 0;
}