C++实验四继承多态(3)

面向对象程序设计实验报告

{

Point *p=new Circle(2.5,1.8,4.5); delete p; return 0; }

源程序②：

#include using namespace std; class Point {

public:

Point(float a,float b):x(a),y(b){} ~Point() {

cout<<\ }

private: float x; float y; };

class Circle:public Point {

public:

Circle(int a,int b,int r):Point(a,b),radius(r){} ~Circle() {

cout<<\ }

private: float radius; };

int main() {

Point *p=new Circle(2.5,1.8,4.5); Circle *pt=new Circle(2.5,1.8,4.5); delete pt; return 0; }

源程序③：

#include using namespace std; class Point {

面向对象程序设计实验报告

public:

Point(float a,float b):x(a),y(b){} virtual ~Point() {

cout<<\ }

private: float x; float y; };

class Circle:public Point {

public:

Circle(float a,float b,float r):Point(a,b),radius(r){} virtual ~Circle() {

cout<<\ }

private: float radius; };

int main() {

Point *p=new Circle(2.5,1.8,4.5); delete p; }

7. 实验任务七

#include using namespace std; //定义抽象基类Shape class Shape {public:

virtual double area() const =0; //纯虚函数 };

//定义Circle类

class Circle:public Shape {

public:

Circle(double r):radius(r){} //结构函数

面向对象程序设计实验报告

virtual double area() const

{return 3.14159*radius*radius;}; //定义虚函数 protected:

double radius; //半径 };

//定义Rectangle类

class Rectangle:public Shape {public:

Rectangle(double w,double h):width(w),height(h){} //结构函数 virtual double area() const {return width*height;} //定义虚函数 protected:

double width,height; //宽与高 };

class Triangle:public Shape {public:

Triangle(double w,double h):width(w),height(h){} //结构函数 virtual double area() const {return 0.5*width*height;} //定义虚函数 protected:

double width,height; //宽与高 };

//输出面积的函数

void printArea(const Shape &s)

{cout<

int main() {

Circle circle(12.6); //建立Circle类对象circle cout<<\ =\

printArea(circle); //输出circle的面积

Rectangle rectangle(4.5,8.4); //建立Rectangle类对象rectangle

cout<<\ printArea(rectangle); //输出rectangle的面积 Triangle triangle(4.5,8.4); //建立Triangle类对象 cout<<\ =\

printArea(triangle); //输出triangle的面积 return 0; }