MyPoint.h

#pragma once
class MyPoint
{
private:
	double x0, y0; //點坐標
public:
	void setPoint(double x, double y);
	double getX0();
	double getY0();
};

MyPoint.cpp

#include "MyPoint.h"

void MyPoint::setPoint(double x, double y)
{
	x0 = x;
	y0 = y;
}
double MyPoint::getX0()
{
	return x0;
}
double MyPoint::getY0()
{
	return y0;
}

MyCircle.h

#pragma once
#include "MyPoint.h"
class MyCircle
{
public:
	void setCir(double x, double y, double r);
	
public:
	char * judge(double x, double y);
	char * judge(MyPoint &p);

private:
	double x1, y1; //?2D?×?±ê
	double r1;  //?2°???
};

MyCircle.cpp

#include "MyCircle.h"

void MyCircle::setCir(double x, double y, double r)
{
	//這裏面也是類的內部
	x1 = x; y1 = y; r1 = r;
}
char* MyCircle::judge(double x, double y)
{
	double s = (x1-x)*(x1-x) + (y1-y)*(y1-y) - r1*r1 ;
	if (s > 0)
	{
		return "在圓外";
	}
	else
	{
		return "在圓內";
	}
}
char* MyCircle::judge(MyPoint &p)
{
	double s = (x1-p.getX0())*(x1-p.getX0()) + (y1-p.getY0())*(y1-p.getY0()) - r1*r1 ;
	if (s > 0)
	{
		return "在圓外";
	}
	else
	{
		return "在圓內";
	}
}

　　main.cpp

#include "iostream"
using namespace std;

#include "MyCircle.h"
#include "MyPoint.h"

void main()
{
	MyCircle c1;
	MyPoint  p1;

	c1.setCir(2, 2, 3);
	p1.setPoint(1, 1);
	cout<<c1.judge(p1.getX0(), p1.getY0())<<endl;
	cout<<c1.judge(p1)<<endl;
	system("pause");

}

C++傳智筆記（5）：C++完整demo