链式表

template<class Node_entry>
struct Node{
	Node_entry entry;
	Node <Node_entry> * next;
	Node();
	Node(Node_entry,Node<Node_entry> *link=NULL);
};

template<class List_entry>
class List{
public:
	~List();
	List(const List<List_entry>&copy);
protected:
	int count;
	Node<List_entry> * head;
	Node<List_entry> * set_position(int position) const;
};

template<class List_entry>
Node <List_entry> * List<List_entry>::set_position (int position) const
{
	Node<List_entry> *q=head;
	for(int i=0;i<position;i++)q=q->next;
	return q;
}

template<class List_entry>
Error_code List<List_entry>::insert(int position,const List_entry &x)
{
	if(position<0 || position>count)
		return range_error;
	Node<List_entry> * new_node,*previous,*following;
	if(position>0){
		previous=set_position(position-1);
		following=previous->next;
	}
	else following=head;
	new_node=new Node<List_entry>(x,following);
	if(new_node == NULL)
		return overflow;
	if(position==0)
		head=new_node;
	else
		previous->next=new_node;
	count++;
	return success;
}