C++多态特性例

#include<iostream>
#include<string>
using namespace std;

class fruit
{
public:
		virtual void how_to_eat()const=0;
		virtual void show_priority()const=0;
        fruit(string a,string b,double c);
		string name;
		string color;
		double price;
};

class apple:public fruit
{
public:
		apple();
		void how_to_eat()const;
		void show_priority()const;
};

class bnana:public fruit
{
public:
		bnana();
		void show_priority()const;
		void how_to_eat()const;
};

fruit::fruit(string a,string b,double c):name(a),color(b),price(c){}
apple::apple():fruit("apple","red",1.23){}
bnana::bnana():fruit("bnana","yellow",0.34){}

void apple::how_to_eat()const
{
	cout<<"直接吃"<<endl;
}
void apple::show_priority()const
{
	cout<<name<<endl<<color<<endl<<price<<endl;
}

void bnana::how_to_eat()const
{
	cout<<"去了皮再吃"<<endl;
}
void bnana::show_priority()const
{
	cout<<name<<endl<<color<<endl<<price<<endl;
}


int main()
{
	fruit *p[2]={NULL};
	p[0]=new apple;
	p[1]=new bnana;
	for(int i=0;i<2;i++)
	{
		p[i]->show_priority();p[i]->how_to_eat();
	}
	return 0;
}