虚函数与纯虚函数请参考：http://blog.csdn.net/hackbuteer1/article/details/7558868

#include<iostream>usingnamespacestd;classAnimal{public:virtualvoideat()=0;virtualvoidsleep()=0;};classCat:publicAnimal{public:voideat(){cout<<"Thecatiseatingnow."<<endl;}voidsleep(){cout<<"Thecatissleepingnow."<<endl;}};classBear:publicAnimal{public:voideat(){cout<<"Thebeariseatingnow."<<endl;}voidsleep(){cout<<"Thebearissleepingnow."<<endl;}};classPanda:publicCat,publicBear{public:voideat(){cout<<"Thepandaiseatingnow."<<endl;}voidsleep(){cout<<"Thepandaissleepingnow."<<endl;}};voidshow(Cat*p){cout<<"========================"<<endl;p->eat();p->sleep();cout<<"========================"<<endl;}intmain(intargc,char*argv[]){Cat*p;Catc;Pandad;p=&c;show(p);p=&d;show(p);return0;}