可以通过创建两个类来解决问题 ：

代码：

#include<iostream>
using namespace std;

class Point
{
public:
	void setX(int x)
	{
		m_X = x;
	}
	int getX()
	{
		return m_X;
	}
	void setY(int y)
	{
		m_Y = y;
	}
	int getY()
	{
		return m_Y;
	}

private:
	int m_X;
	int m_Y;
	
};

class Circle
{
public:
	void setR(int r)
	{
		m_R = r;
	}
	int getR()
	{
		return m_R;
	}
	void setCenter(Point center)
	{
		m_Center = center;
	}
	Point getCenter()
	{
		return m_Center;
	}

private:
	int m_R;
	Point m_Center;
};

void isCircle(Circle& c, Point& p)
{
	int distance = (c.getCenter().getX() - p.getX())* (c.getCenter().getX() - p.getX()) + (c.getCenter().getY() - p.getY()) * (c.getCenter().getY() - p.getY());
	int rDistance = c.getR() * c.getR();
	if (distance == rDistance)
	{
		cout << "点在圆上" << endl;
	}
	else if (distance > rDistance)
	{
		cout << "点在圆外" << endl;
	}
	else
	{
		cout << "点在圆内" << endl;
	}

}


int main()
{
	Circle c;
	c.setR(2);
	Point center;
	center.setX(0);
	center.setY(0);
	c.setCenter(center);

	Point p;
	p.setX(3);
	p.setY(3);

	isCircle(c, p);

	system("pause");
	return 0;
}

eg:

点（3，3）在圆外