class Circle: public Point{protected: double r;public: Circle(double _x=0, double _y=0, double _r=0): Point(_x, _y), r(_r){} friend istream& operator>>(istream& in, Circle& c){ in>>dynamic_cast<Point&>(c); cout<<"请输入圆的半径: "; in>>c.r; return in; } friend ostream& operator<<(ostream& out, const Circle& c){ out<<"圆心坐标为"<<dynamic_cast<const Point&>(c)<<"，半径为"<<c.r; return out; } double area(){ //计算圆的面积 return 3.1415926*r*r; }};

这段代码定义了一个Circle类，它继承自Point类，表示一个圆。其中，数据成员包括圆心坐标x和y，以及半径r。构造函数中使用了基类的构造函数来初始化x和y，而r则使用了初始化列表进行初始化。此外，类中还定义了一个计算圆面积的函数area()。

在这个类中，还重载了输入输出运算符">>"和"<<"，用于输入和输出圆的信息。输入运算符中，先调用基类的输入运算符来输入圆心坐标，然后再输入半径r。输出运算符中，先调用基类的输出运算符来输出圆心坐标，然后再输出半径r。

总之，这个Circle类可以用于表示一个圆，并且可以输入输出圆的信息，并计算圆的面积。

相关问题

请以点类Point为基类派生出一个圆类Circle。圆类Circle的数据成员为r（私有属性，存储圆的半径，圆心的点坐标通过继承点类Point加以实现），成员函数有构造函数Circle、计算圆的面积函数Area、计算圆的周长函数Perimeter和输出函数Display，其中构造函数实现基类和圆类的数据成员的初始化，Display函数实现圆心坐标（利用基类Point的Display实现）、圆的半径、圆的面积（利用Area函数实现）和圆的周长（利用Perimeter函数实现）的输出。请编写圆类的定义及成员函数实现，并在主函数中定义圆类对象，验证各个函数的正确性。 说明：圆周率PI的取值为3.14 已知Point类及main代码如下：（不允许改动） class Point { public: ​Point(double xx,double yy); //constructor ​void Display();​ //display point​ private: ​double x,y; //平面的点坐标x，y }; Point::Point(double xx,double yy) {​ ​x=xx; ​y=yy; } void Point::Display() {​ ​cout<<"Point("<<x<<","<<y<<")"<<endl; } int main() { ​double x,y,r; ​cin>>x>>y>>r; //圆心的点坐标及圆的半径 ​Circle C(x,y,r); ​C.Display(); //输出圆心点坐标，圆的半径，圆的面积，圆的周长 ​return 0;

以下是圆类的定义及成员函数实现：

#include <iostream>
using namespace std;

const double PI = 3.14;

class Point {
public:
    Point(double xx, double yy); //constructor
    void Display(); //display point
protected:
    double x, y; //平面的点坐标x，y
};

Point::Point(double xx, double yy) {
    x = xx;
    y = yy;
}

void Point::Display() {
    cout << "Point(" << x << "," << y << ")" << endl;
}

class Circle : public Point {
public:
    Circle(double xx, double yy, double rr); //constructor
    double Area(); //计算圆的面积函数
    double Perimeter(); //计算圆的周长函数
    void Display(); //输出函数
private:
    double r; //圆的半径
};

Circle::Circle(double xx, double yy, double rr) : Point(xx, yy) {
    r = rr;
}

double Circle::Area() {
    return PI * r * r;
}

double Circle::Perimeter() {
    return 2 * PI * r;
}

void Circle::Display() {
    Point::Display();
    cout << "圆的半径：" << r << endl;
    cout << "圆的面积：" << Area() << endl;
    cout << "圆的周长：" << Perimeter() << endl;
}

int main() {
    double x, y, r;
    cin >> x >> y >> r; //圆心的点坐标及圆的半径
    Circle C(x, y, r);
    C.Display(); //输出圆心点坐标，圆的半径，圆的面积，圆的周长
    return ;
}

在主函数中定义了一个圆类对象C，通过输入圆心的点坐标及圆的半径来初始化该对象，然后调用Display函数输出圆心点坐标，圆的半径，圆的面积和圆的周长。

能补充这段代码吗import javafx.application.Application; import javafx.scene.Scene; import javafx.scene.layout.Pane; import javafx.scene.paint.Color; import javafx.scene.shape.Circle; import javafx.scene.shape.Rectangle; import javafx.scene.shape.Polygon; import javafx.stage.Stage; import java.io.FileInputStream; import java.io.IOException; import java.util.Properties; abstract class Shape { protected Color color; protected double area; protected double perimeter; protected double positionX; protected double positionY; public abstract void calculateArea(); public abstract void calculatePerimeter(); public abstract void draw(Pane pane); public void setPosition(double x, double y) { this.positionX = x; this.positionY = y; } } class CircleShape extends Shape { private double radius; public CircleShape(double radius) { this.radius = radius; this.color = Color.RED; } @Override public void calculateArea() { this.area = Math.PI * Math.pow(radius, 2); } @Override public void calculatePerimeter() { this.perimeter = 2 * Math.PI * radius; } @Override public void draw(Pane pane) { Circle circle = new Circle(radius); circle.setFill(color); circle.setLayoutX(positionX); circle.setLayoutY(positionY); pane.getChildren().add(circle); } } class RectangleShape extends Shape { private double width; private double height; public RectangleShape(double width, double height) { this.width = width; this.height = height; this.color = Color.BLUE; } @Override public void calculateArea() { this.area = width * height; } @Override public void calculatePerimeter() { this.perimeter = 2 * (width + height); } @Override public void draw(Pane pane) { Rectangle rectangle = new Rectangle(width, height); rectangle.setFill(color); rectangle.setLayoutX(positionX); rectangle.setLayoutY(positionY); pane.getChildren().add(rectangle); } } class TriangleShape extends Shape { private double[] points; public TriangleShape(double[] points) { this.points = points; this.color = Color.GREEN; } @Override public void calculateArea() { double x1 = points[0]; double y1 = points[1]; doubl

e x2 = points[2]; double y2 = points[3]; double x3 = points[4]; double y3 = points[5]; this.area = Math.abs((x1 * (y2 - y3) + x2 * (y3 - y1) + x3 * (y1 - y2)) / 2.0); } @Override public void calculatePerimeter() { double side1 = Math.sqrt(Math.pow(points[0] - points[2], 2) + Math.pow(points[1] - points[3], 2)); double side2 = Math.sqrt(Math.pow(points[2] - points[4], 2) + Math.pow(points[3] - points[5], 2)); double side3 = Math.sqrt(Math.pow(points[4] - points[0], 2) + Math.pow(points[5] - points[1], 2)); this.perimeter = side1 + side2 + side3; } @Override public void draw(Pane pane) { Polygon triangle = new Polygon(points); triangle.setFill(color); triangle.setLayoutX(positionX); triangle.setLayoutY(positionY); pane.getChildren().add(triangle); } } public class Main extends Application { @Override public void start(Stage primaryStage) throws Exception { Pane pane = new Pane(); Properties prop = new Properties(); try { FileInputStream input = new FileInputStream("config.properties"); prop.load(input); input.close(); } catch (IOException ex) { ex.printStackTrace(); } for (int i = 1; i <= 3; i++) { String shapeType = prop.getProperty("shape" + i + ".type"); Shape shape; if (shapeType.equals("circle")) { double radius = Double.parseDouble(prop.getProperty("shape" + i + ".radius")); shape = new CircleShape(radius); } else if (shapeType.equals("rectangle")) { double width = Double.parseDouble(prop.getProperty("shape" + i + ".width")); double height = Double.parseDouble(prop.getProperty("shape" + i + ".height")); shape = new RectangleShape(width, height); } else { double[] points = new double[6]; for (int j = 0; j < 6; j++) { points[j] = Double.parseDouble(prop.getProperty("shape" + i + ".point" + (j+1))); } shape = new TriangleShape(points); } shape.calculateArea(); shape.calculatePerimeter(); double posX = Double.parseDouble(prop.getProperty("shape" + i + ".posX")); double posY = Double.parseDouble(prop.getProperty("shape" + i + ".posY")); shape.setPosition(posX, posY); shape.draw(pane); } Scene scene = new Scene(pane, 500, 500); primaryStage.setScene(scene); primaryStage.show(); } public static void main(String[] args) { launch(args); } }

这段代码实现了一个基于JavaFX的图形绘制应用，它定义了一个抽象类 Shape 和三个子类 CircleShape、RectangleShape 和 TriangleShape，分别对应圆形、矩形和三角形，每个子类都实现了抽象方法 calculateArea()、calculatePerimeter() 和 draw()。这些方法用于计算每个图形的面积、周长和绘制图形。在主类 Main 中，从配置文件 config.properties 中读取每个图形的类型、参数和位置，然后创建相应的图形对象并调用其方法进行计算和绘制。最后将绘制结果显示在 JavaFX 的场景中。