b_9_1.cpp

C++应用教程原码,里面包含该书中有十三章内容的代码,详细具体

#include "stdafx.h"
#include <iostream>
#include <string>
#include<iomanip>
using namespace std;
const double PI=3.1416;
class shape{
public:
	virtual double area()=0;
};
class Circle:public shape {
public:
	Circle(double x)
		:r(x){ }
	double area()
	{ return PI*r*r;}
private:
	double r;
};
class Triangle:public shape
{
public:
	Triangle(double i,double j)
		:high(i),width(j){ }
	double area()
	{ return 0.5*high*width;	}
private:
	double high,width;
};
class Rectangle:public shape {
public:
	Rectangle(double i,double j)
		:high(i),width(j){ }
	double area()
	{ return high*width;}
private:
	double high,width;
};
void main()
{
	shape *ptr;
	Triangle triangle(8,11);
	Rectangle rectangle(8,11);
	Circle circle(7);
	ptr=&circle;
	cout<<"圆的面积是:"<<ptr->area()<<endl;
	ptr=&rectangle;
	cout<<"矩形的面积是:"<<ptr->area()<<endl;
	ptr=&triangle;
	cout<<"三角形的面积是:"<<ptr->area();
    cin.get(); //等待结束，以便调测程序，可以删除
}