base::print(ostream& os);

struct base
{
base(string sz):basename(sz){}
string name(){return basename;}
virtual void print(ostream& os){os<<basename;}
private:
string basename;
};
struct derived:public base
{
derived(string sz,int val):base(sz),men(val){}
void print(){
base::print(ostream& os);
os<<" "<<men;
}
private:
int men;
};
这里 base::print(ostream& os);有问题，不知道该怎么改