//定義items類(lèi)
class items{
public:
	
	items();
	virtual ~items();
	virtual int compare(items *);  //does the to items equal to each other?
	virtual items *clone();        //make a copy items
	virtual int key();             //generate a key for the items ,used in the hash tree
	virtual void dump();		   //print out the items' content
protected:
};