類：點和圓的關係

#include <iostream>
#include <string>
using namespace std;
class Point
{
private:
	double m_x;
	double m_y;
public:
	void setXY(double x,double y)
	{
		m_x = x;
		m_y = y;
	}
	int getX()
	{
		return m_x;
	}
	int getY()
	{
		return m_y;
	}
};
class Circle
{
private:
	Point m_center;
	double m_r;
public:
	void setR(double R)
	{
		m_r = R;
	}
	double getR()
	{
		return m_r;
	}
	
	void setCenter(Point center)
	{
		m_center = center;
	}
	Point getCenter()
	{
		return m_center;
	}
};



void isInCircel(Circle &c,Point &p)
{
	double distance = (c.getCenter().getX() - p.getX())*(c.getCenter().getX() - p.getX()) + (c.getCenter().getY() - p.getY())*(c.getCenter().getY() - p.getY());
	double rdistance = c.getR()*c.getR();
	
	if (distance > rdistance)
	{
		cout << "點在圓外"<< endl; 
	}
	else if (distance < rdistance)
	{
		cout << "點在圓內"<< endl; 
	}
	else 
	{
		cout << "點在圓上"<< endl; 
	}
}
 
 int main()
 {
 	//創建點
	Point p;
	p.setXY(3,4);
	Point p1;
	p1.setXY(12,13); 
 	//創建圓；
	Circle c;
	c.setR(12);
	c.setCenter(p1);
	
	isInCircel(c,p); 
	return 0;
 }