为什么要用继承

子类不必复制父类的任何属性，已经继承下来了；易于维护与编写；

类的继承与派生

访问控制规则

一般只使用Public！

构造函数的继承与析构函数的继承

构造函数不被继承！



在创建子类对象的时候，会先调用父类的构造函数，再调用子类的构造函数
在消亡子类对象的时候，会先调用子类的析构函数，再调用父类的析构函数

派生类构造函数

派生类析构函数

作业

main.cpp

#include "shape.h"
#include "circle.h"
#include "rectangle.h"
#include "roundrectangle.h" 
#include <iostream>
using namespace std;
/* run this program using the console pauser or add your own getch, system("pause") or input loop */

int main(void) {
	shape myshape1("red");
	myshape1.display();
	
	circle mycircle1;
	mycircle1.display();
	
	circle mycircle2("red",2);
	mycircle2.display();
	
	Rectangle myrectangle1("green",2,3);
	myrectangle1.display();
	
	RoundRectangle myroundrectangle1("yeelow",2,3,1);
	myroundrectangle1.display();
	return 0;
}

shape.cpp

#include "shape.h"
#include <iostream>
using namespace std;		
	shape::shape():color("white"){
		cout<<"无参创建shape"<<endl;
	}
	shape::shape(string color){
		this->color = color;
		cout<<"有参创建shape"<<endl;
	}
	shape::~shape(){
		cout<<"消亡shape"<<endl;
	}
	string shape::getColor(){
		return this->color;
	}
	void shape::setcolor(char color){
		this->color = color;
	}
	void shape::display(){
		cout<<"color:"<<getColor()<<endl;
	}

shape.h

#ifndef SHAPE_H
#define SHAPE_H
#include <string>
#include <iostream>
using namespace std;
class shape{
	private:
		string color;
	public:
		shape();
		shape(string color);
		~shape();
		string getColor();
		void setcolor(char color);
		void display();
};

#endif

circle.cpp

#include "circle.h"
#include "shape.h"
#include <iostream>
	const double pi = 3.14;
	circle::circle(){
		radius = 1;
		cout<<"无参创建circle"<<endl;
	}
	circle::circle(string color,double radius):shape(color){
		this->radius = radius;
		cout<<"有参创建circle"<<endl;
	}
	circle::~circle(){
		cout<<"消亡circle"<<endl;
	}
	double circle::getRadius(){
		return this->radius;
	}
	void circle::setradius(double radius){
		this->radius = radius;	
	}
	double circle::getArea(){
		return pi*radius*radius;
	}
	void circle::display(){
		shape::display();
		cout<<"R="<<getRadius()<<","<<"Area="<<getArea()<<endl;
	}

circle.h

#ifndef CIRCLE_H
#define CIRCLE_H
#include <string>
#include "shape.h"

class circle:public shape{
	private:
		double radius;
	public:
		circle();
		circle(string color,double radius);
		~circle();
		double getRadius();
		void setradius(double radius);
		double getArea();
		void display();
};



#endif

rectangle.cpp

#include "rectangle.h"
#include "shape.h"
#include <iostream>

	Rectangle::Rectangle(){
		width = 1;
		height = 1;
		cout<<"无参创建Rectangle"<<endl;
	}
	Rectangle::Rectangle(string color,double width,double height):shape(color){
		this->width = width;
		this->height = height;
		cout<<"有参创建Rectangle"<<endl; 
	}
	Rectangle::~Rectangle(){
		cout<<"消亡Rectangle"<<endl;
	}
	double Rectangle::getWidth(){
		return width; 
	}
	double Rectangle::getHeight(){
		return height;
	}
	void Rectangle::setWidth(double width){
		this->width = width;
	}
	void Rectangle::setHeight(double height){
		this->height = height;
	}
	double Rectangle::getArea(){
		return width*height;
	}
	void Rectangle::display(){
		shape::display();
		cout<<"width="<<getWidth()<<","<<"Height="<<getHeight()<<","<<"Area="<<getArea()<<endl;
	}

rectangle.h

#ifndef RECTANGLE_H
#define RECTANGLE_H
#include <string>
#include "shape.h"

class Rectangle:public shape{
	private:
		double width;
		double height;
	public:
		Rectangle();
		Rectangle(string color,double width,double height);
		~Rectangle();
		double getWidth();
		double getHeight();
		void setWidth(double width);
		void setHeight(double height);
		double getArea();
		void display();
};


#endif

roundrectangle.cpp

#include "roundrectangle.h"
#include "rectangle.h"
#include"shape.h"
#include <iostream>
	RoundRectangle::RoundRectangle(){
		this->roundRadius = 1;
		cout<<"无参创建RoundRectangle"<<endl; 
	}
	RoundRectangle::RoundRectangle(string color,double width,double height,double roundRadius):Rectangle(color,width,height){
		this->roundRadius = roundRadius;
		cout<<"有参创建RoundRectangle"<<endl;
	}
	RoundRectangle::~RoundRectangle(){
		cout<<"消亡RoundRectangle"<<endl; 
	}
	double RoundRectangle::getRoundradius(){
		return roundRadius;
	}
	void RoundRectangle::setRoundradius(double roundRadius){
		this->roundRadius = roundRadius;
	}
	double RoundRectangle::getArea(){
		return Rectangle::getWidth()*Rectangle::getHeight()+(3.14*roundRadius*roundRadius)/2;
	}
	void RoundRectangle::display(){
		shape::display();
		cout<<"width="<<Rectangle::getWidth()<<","<<"Height="<<Rectangle::getHeight()<<","<<"Area="<<getArea()<<endl;
	}

roundrectangle.h

#ifndef ROUNDRECTANGLE_H
#define ROUNDRECTANGLE_H
#include <string>
#include "rectangle.h"

class RoundRectangle:public Rectangle{
	private:
		double roundRadius;
	public:
		RoundRectangle();
		RoundRectangle(string color,double width,double height,double roundRadius);
		~RoundRectangle();
		double getRoundradius();
		void setRoundradius(double roundRadius);
		double getArea();
		void display();
};


#endif