/*纯虚函数与抽象类-----枯等街寒又何妨2014/01/05*/
#include<iostream>
#include<cmath>
using namespace std;
const double pi=3.14159;
class Shape
{
public:
virtual void show(void)=0;
virtual double area(void)=0;
};
class triangle:public Shape
{
public:
triangle(double=0,double=0,double=0);
void show(void);
double area(void);
private:
double a,b,c;
};
class rectangle :public Shape
{
public:
rectangle(double=0,double=0);
void show(void );
double area(void );......
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