C++作业3

项目二、友元函数

#include<iostream>
using namespace std;
#include<math.h>
class Distance
{
private:
double x;
double y;
public:
Distance(double xx=0,double yy=0):x(xx),y(yy){}
double distance1();
friend double distance2(Distance &);
double get_x();
double get_y();
};
double Distance::distance1()
{
double distance;
distance=sqrt(x*x+y*y);
return distance;
}
double distance2(Distance &c)
{
double distance;
distance=sqrt(c.x*c.x+c.y*c.y);
return distance;
}
double Distance::get_x()
{
return x;
}
double Distance::get_y()
{
return y;
}
double distance3(Distance &c)
{
double distance,a,b;
a=c.get_x();
b=c.get_y();
distance=sqrt(a*a+b*b);
return distance;
}
int main()
{
Distance c1(3.0,4.0);
cout<<"distance is :"<<c1.distance1()<<endl;
cout<<"distance is :"<<distance2(c1)<<endl;
cout<<"distance is :"<<distance3(c1)<<endl;
return 0;
}