最基本的单链表C++

// 单链表.cpp -- 最基本的单链表C++// Singly-linked list nodetemplate <class Elem> class Link{ public:  Elem element;   // value for this node  Link *next;    // pointer to next node in list  Link(const Elem& elemval, Link* nextval = NULL)  { element = elemval; next = nextval;}  Link (Link* nextval = NULL)  { next = nextval;}};// Linked list implementationtemplate <class Elem> class LList: public Link<Elem>{ private:  Link <Elem>* head;  // Pointer to list header  Link <Elem>* tail;  // Pointer to last Elem in list  Link <Elem>* fence;  // Last element on left side  int leftcnt;   // Size of left partition  int rightcnt;   // Size of right partition  void init()    // Intialization routine  {  fence = tail = head = new Link <Elem>;  leftcnt = rightcnt = 0;  }  void removeall()  // return nodes to free store  {  while(head != NULL)   {   fence = head;   head = head -> next;   delete fence;   }  } public:  LList(int size = DefaultListSize) { init();}  ~LList() {removeall();} // Destructor  void clear() {removeall(); init();}  bool insert(const Elem&);  bool append(const elem&);  bool remove(Elem&);  void setStart()  { fence = head; rightcnt += leftcnt; leftcnt = 0; }  void setEnd()  {   fence = tail; leftcnt += rightcnt; rightcnt = 0;}  void prev();  void next();  {   if (fence != tail) // don't move fence if right empty   {    fence = fence -> next;    rightcnt--;    leftcnt++;   }  }  int leftLength()const {return leftcnt;}  int rightLength()const {return rightcnt;}  bool setPos(int pos);  bool getValue(Elem& it) const  {   if {rightLength() == 0) return false;   // 当带了表结头，要先指向下一个元素取值。   // 如果带了表结头后，取值不是还是0,1,2,3...所以就要看具体的功能来写   it = fence -> next -> element;    return true;  }   void print() const;};template <class Elem> // Insert at front of right partitionbool LList <Elem>::insert(const Elem& item) { fence -> next = new Link <Elem> (item, fence -> next); if (tail == fence) tail = fence -> next;  // new tail rightcnt++; return true; }template <class Elem> // Append Elem to end of the listbool LList <Elem>::append(const Elem& item) { tail = tail -> next = new Link<Elem>(item, NULL); rightcnt++; return true; }// Remove and return first Elem in right partitiontemplate <class Elem> bool LList<Elem>::remove(Elem& it) { if (fence -> next == NULL) return false; // Empty right it = fence -> next -> element;    // Remember value Link<Elem>* ltemp = fence -> next;   // Remember link node fence -> next = ltemp -> next;    // Remove from list if (tail == ltemp) tail = fence;   // Reset tail delete ltemp; rightcnt--; return true; }// Move fence one step left; no change if left is emptytemplate <class Elem> void LList<Elem>::setPos(int pos) { if ((pos < 0) || (pos > rightcnt + leftcnt)) return false; fence = head; for (int i = 0; i < pos; i++) fence = fence -> next; return true; }// Set the size of left partition to pos template <class Elem> bool LList<Elem>::setPos(int pos) { if ((pos < 0) || (pos > rightcnt + leftcnt)) return false; fence = head; for(int = 0; i < pos; i++) fence = fence -> next; return true; }template <class elem> void LList<Elem>::print() const { Link<Elem>* temp = head; cout << " < "; while(temp != fence)  {  cout << temp -> next -> element << " ";  temp = temp -> next;  } cout << " | "; while(temp -> next != NULL)  {  cout << temp -> next -> element << " ";  temp = temp -> next;  } cout << ">\n"; }