C++实现双向链表

 #pragma once #include  #include  #include  using namespace std; typedef int DataType; struct ListNode { ListNode* _next;   //存放下一个节点地址 ListNode* _prev;     //存放上一个节点地址 DataType _data; ListNode(DataType x) :_data(x) , _next(NULL) , _prev(NULL) {} }; class List { typedef ListNode Node; public: List() :_head(new Node(DataType())) { _head->_next = _head; _head->_prev = _head; } List(const List& l) :_head(new Node(DataType())) { _head->_next = _head; _head->_prev = _head; Node* cur = l._head->_next; while (cur != l._head) { PushBack(cur->_data); cur = cur->_next; } } List& operator=(List& l) { if (this != &l) { swap(_head, l._head); } return *this; } ~List() { Node* cur = _head->_next; while (cur != _head) { Node* next = cur->_next; delete cur; cur = next; } delete _head; _head = NULL; } void Print() const { Node* cur = _head->_next; cout << "head->"; while (cur != _head) { cout << cur->_data << "->"; cur = cur->_next; } cout << endl; Node* tail = _head->_prev; while (tail != _head) { cout << tail->_data << "->"; tail = tail->_prev; } cout << "head" << endl; } void PushBack(DataType x); void PushFront(DataType x); void PopBack(); void PopFront(); ListNode* Find(DataType x); void Insert(Node* pos, DataType x); void Erase(Node* pos); private: Node* _head; }; void List::PushBack(DataType x) { Node* tail = _head->_prev; Node* new_node = new Node(x); tail->_next = new_node; new_node->_prev = tail; new_node->_next = _head; _head->_prev = new_node; //Insert(_head, x); } void List::PushFront(DataType x) { Node* cur = _head->_next; Node* new_node = new Node(x); new_node->_next = cur; cur->_prev = new_node; new_node->_prev = _head; _head->_next = new_node; //Insert(_head->_next, x); } void List::PopBack() { Node* to_delete = _head->_prev; Node* cur = to_delete->_prev; cur->_next = _head; _head->_prev = cur; delete to_delete; //Erase(_head->_prev); } void List::PopFront() { Node* to_delete = _head->_next; Node* cur = to_delete->_next; cur->_prev = _head; _head->_next = cur; delete to_delete; //Erase(_head->_next); } ListNode* List::Find(DataType x) { Node* cur = _head->_next; while (cur != _head) { if (cur->_data == x) { return cur; } cur = cur->_next; } return NULL; } void List::Insert(Node* pos, DataType x) { assert(pos); Node* prev = pos->_prev; Node* new_node = new Node(x); new_node->_next = pos; pos->_prev = new_node; prev->_next = new_node; new_node->_prev = prev; } void List::Erase(Node* pos) { assert(pos); Node* prev = pos->_prev; Node* next = pos->_next; prev->_next = next; next->_prev = prev; delete pos; } void TestList() { List l; l.PushBack(1); l.PushBack(2); l.PushBack(3); l.PushBack(4); l.PopBack(); l.Print(); ListNode* pos = l.Find(2); printf("pos->_data expext 2, actual %d:[%p]\n", pos->_data, pos); pos = l.Find(4); printf("pos->_data expext NULL, actual [%p]\n", pos); pos = l.Find(1); printf("pos->_data expext 1, actual %d:[%p]\n", pos->_data, pos); l.Insert(pos, 0); l.Print(); l.Erase(pos); l.Print(); List l1(l); l1.PushFront(8); l1.PushFront(7); l1.PushFront(6); l1.PushFront(5); l1.PopFront(); l1.Print(); List l2; l2 = l; l2.Print(); }

 #include "List.h" int main() { cout << "双向链表：" << endl; TestList(); return 0; }