[C++知识库]c++第三次实验：类的多态性

?1.基类指针数组？？

#include <bits/stdc++.h>
#define PI 3.1415926
using namespace std;

class Shape{
	public:
		Shape(){}
		virtual float girth() =0;//基类求周长函数 
		virtual float area() =0;//基类求面积函数 
		virtual void display() =0;//基类输出虚函数
		~Shape(){} 
};

class Circle:public Shape{
	protected:
		float radius;//半径
	public:
		Circle(){}
		void setRadius(float r);
		virtual float girth();
		virtual float area();
		virtual void display();
		~Circle(){}
};

void Circle::setRadius(float r)
{
	radius = r;
}

float Circle::girth(){
	return 2*PI*radius;
}

float Circle::area(){
	return PI*radius*radius;
}

void Circle::display(){
	cout<<"圆的周长为:"<<Circle::girth()<<endl; 
	cout<<"圆的面积为:"<<Circle::area()<<endl;
}

class Square:public Shape{
	protected:
		float len;
	public:
		Square(){}
		void setLen(float l);
		virtual float girth();
		virtual float area();
		virtual void display();
		~Square(){}
};

void Square::setLen(float l)
{
	len = l;
}

float Square::girth(){
	return 4*len;
}

float Square::area(){
	return len*len;
}

void Square::display(){
	cout<<"正方形的周长为:"<<Square::girth()<<endl; 
	cout<<"正方形的面积为:"<<Square::area()<<endl;
}

class Rectangle:public Shape{
	protected:
		float lon;
		float wide;
	public:
		Rectangle(){}
		void setLW(float l,float w);
		virtual float girth();
		virtual float area();
		virtual void display();
		~Rectangle(){}
};

void Rectangle::setLW(float l,float w)
{
	lon = l;
	wide = w;
}

float Rectangle::girth(){
	return 2*(lon+wide);
}

float Rectangle::area(){
	return lon*wide;
}

void Rectangle::display(){
	cout<<"长方形的周长为:"<<Rectangle::girth()<<endl; 
	cout<<"长方形的面积为:"<<Rectangle::area()<<endl;
}

class Trapezoid:public Shape{
	protected:
		float shang;
		float xia;
		float gao;
		float zuo;//左腰 
		float you;//右腰 
	public:
		Trapezoid(){}
		void setData(float s,float x,float g,float z,float y);
		virtual float girth();
		virtual float area();
		virtual void display();
		~Trapezoid(){}
};

void Trapezoid::setData(float s,float x,float g,float z,float y)
{
	shang = s;
	xia = x;
	gao = g;
	zuo = z;
	you = y; 
}

float Trapezoid::girth(){
	return (shang+xia+zuo+you);
}

float Trapezoid::area(){
	return (shang+xia)*gao/2;
}

void Trapezoid::display(){
	cout<<"梯形的周长为:"<<Trapezoid::girth()<<endl; 
	cout<<"梯形的面积为:"<<Trapezoid::area()<<endl;
}

class Triangle:public Shape{
	protected:
		float di;
		float zuo;//左边 
		float you;//右边 
		float gao;
	public:
		Triangle(){}
		void set(float d,float z,float y,float g);
		virtual float girth();
		virtual float area();
		virtual void display();
		~Triangle(){}
};

void Triangle::set(float d,float z,float y,float g)
{
	di = d;
	zuo = z;
	you = y;
	gao = g;
}

float Triangle::girth(){
	return di+zuo+you;
}

float Triangle::area(){
	return di*gao/2;
}

void Triangle::display(){
	cout<<"三角形的周长为:"<<Triangle::girth()<<endl; 
	cout<<"三角形的面积为:"<<Triangle::area()<<endl;
}

int main()
{
	float r,s,lon,wid;
	float shang,xia,zuoyao,youyao,gao;//梯形
	float di,h,zuo,you;//三角形 
	cout<<"请输入圆的半径：";
	cin>>r;
	cout<<"请输入正方形的边长：";
	cin>>s;
	cout<<"请输入长方形的长、宽：";
	cin>>lon>>wid;
	cout<<"请输入梯形的上底、下底、高、左腰长、右腰长：";
	cin>>shang>>xia>>gao>>zuoyao>>youyao;
	cout<<"请输入三角形的底、左边长度、右边长度、高：";
	cin>>di>>zuo>>you>>h;
	Circle circle;
	Square square;
	Rectangle rectangle;
	Trapezoid trapezoid;
	Triangle triangle;
	circle.setRadius(r);
	square.setLen(s);
	rectangle.setLW(lon,wid);
	trapezoid.setData(shang,xia,gao,zuoyao,youyao);
	triangle.set(di,zuo,you,h);
	Shape *p[6]={&circle,&square,&rectangle,&trapezoid,&triangle};//定义基类指针数组，使之每个成员指向一个派生类对象
	int i,girthsum=0,areasum=0;
	for(i=0;i<5;i++){
		girthsum +=p[i]->girth();
		areasum +=p[i]->area();
		p[i]->display();
	} 
	cout<<"****************************"<<endl;
	cout<<"所有图形周长之和："<<girthsum<<endl; 
	cout<<"所有图形面积之和："<<areasum<<endl;
	return 0;
}