508.cpp

来自「C++实训教程」· C++ 代码 · 共 46 行

//508.cpp
#include <iostream.h>
#include <math.h>
class A;
class B
{
		int sum;
	public:
		B(){ sum=1;}
		B(int a,int b){sum=a*a+b*b;}
		int Larger(B b,A a);
};
class A //B must be before A, for A references the B::Larger()
{
	friend int B::Larger(B b,A a);//use  B::Larger()!
	private:int num;
	public:
		A(){num=1;}
		A(int a,int b){num=4*a+b;}
		void Display(void){cout<<num<< endl;}
};
int B::Larger(B b,A a)
{
 return (b.sum > a.num);
}
main(void)
{
	int n=3 , i,j;
	for(i=2;i<=n;i++)
		for(j=2;j<=n;j++)
		{
			B objB(i,j);
			A objA(i,j);
			cout << "i=" << i <<" , j=" <<j<<"  ";
			if(objB.Larger(objB,objA))
			{cout << "B obj is Larger , the small num is ";   objA.Display();}
			else  cout << "B obj is not Larger\n";
		}
	return 0;
}
/*
i=2 , j=2  B obj is not Larger
i=2 , j=3  B obj is Larger , the small num is 11
i=3 , j=2  B obj is not Larger
i=3 , j=3  B obj is Larger , the small num is 15
*/