C++写友元

---

C++
类,友元

声明Book与Ruler两个类，二者都有weight属性，定义二者的一个友元函数totalWeight（），计算二者的重量和。

#include<iostream>
using namespace std;
class Ruler;
class Book
{
	private:
		int weight1;
		friend void totalWeight(Book &b,Ruler &r);
	public:
		void init();
};

void Book::init()
{
	cout<<"请输入书的重量："<<endl;
	cin>>weight1;
}

class Ruler
{
	private:
		int weight2;
		friend void totalWeight(Book &b,Ruler &r);
	public:
		void init();
};

void Ruler::init()
{
	cout<<"请输入尺子的重量："<<endl;
	cin>>weight2;
}

void totalWeight(Book &b,Ruler &r)
{
	cout<<"二者的重量和为："<<b.weight1+r.weight2<<endl; 
 } 

int main()
{
	Book book;
	Ruler ruler;
	book.init();
	ruler.init();
	totalWeight(book,ruler);
	return 0;
}