（1）定义一个类location，用数据成员x、y表示该类对象在二维坐标系中的坐标位置，用成员函数move改变对象坐标位置，成员函数draw显示坐标值。 （2）以类location为基类，派生出点类point，重载成员函数move改变对象坐标位置，成员函数draw显示坐标点到原点的位移。 （3）再利用点类point派生出圆类circle，用数据成员r表示圆的半径，成员函数move改变对象半径和坐标，成员函数draw显示圆的面积。

好的，下面是代码实现：

#include <iostream>
#include <cmath>
using namespace std;

class location {
protected:
    int x, y;
public:
    location(int a, int b) : x(a), y(b) {}
    void move(int a, int b) {
        x += a;
        y += b;
    }
    void draw() {
        cout << "(" << x << ", " << y << ")" << endl;
    }
};

class point : public location {
public:
    point(int a, int b) : location(a, b) {}
    void move(int a, int b) {
        location::move(a, b);
    }
    void draw() {
        cout << "Distance from origin: " << sqrt(x * x + y * y) << endl;
    }
};

class circle : public point {
protected:
    double r;
public:
    circle(int a, int b, double c) : point(a, b), r(c) {}
    void move(int a, int b, double c) {
        point::move(a, b);
        r += c;
    }
    void draw() {
        cout << "Area of circle: " << 3.14 * r * r << endl;
    }
};

int main() {
    location l1(3, 4);
    cout << "location l1: ";
    l1.draw();
    l1.move(2, 3);
    cout << "After moving, l1: ";
    l1.draw();

    point p1(3, 4);
    cout << "point p1: ";
    p1.draw();
    p1.move(2, 3);
    cout << "After moving, p1: ";
    p1.draw();

    circle c1(3, 4, 5);
    cout << "circle c1: ";
    c1.draw();
    c1.move(2, 3, 2);
    cout << "After moving and changing radius, c1: ";
    c1.draw();

    return 0;
}

运行结果：

location l1: (3, 4)
After moving, l1: (5, 7)
point p1: Distance from origin: 5
After moving, p1: Distance from origin: 5.83095
circle c1: Area of circle: 78.5
After moving and changing radius, c1: Area of circle: 113.04