511.cpp

C++实训教程

//511.cpp  FriendMember.cpp
#include <iostream.h>
#include <math.h>
class X;
class Y
{
	private: int m,n;
	public:
		Y(){ m=n=0;}
		Y(int mm,int nn){m=mm;n=nn;}
		int fn(X a);
};
class X
{
	friend int Y::fn(X a);
	friend void Show(Y b,X a);
	private:int num;
	public:
	   X(){num=0;}
	   X(int nn){num=nn;}
};

int Y::fn(X a)
{
 	return sqrt(n*n + m*m + a.num*a.num);
}
void Show(Y b,X a);
main(void)
{
	X x1(3),x2(40);
	Y y1(0,-4),y2(-30,0);
	Show(y1,x1);
	Show(y2,x2);
	return 0;
}
void Show(Y b,X a)
{
	cout << "The result is " << b.fn(a)<<endl;
}

/*
The result is 5
The result is 50

*/