chang.h

这是我无意中做的东西

class chang
{
public:
int a,b,s;
void input(){cin>>a>>b;}
void showarea(){s=a*b;cout<<s<<endl;}
};
class zheng:public chang
{
public:
int a,s;
void input(){cin>>a;}
void showarea(){s=a*a;cout<<s<<endl;}
};