Implementation of basic functions in doubly linked list

#include <iostream>using namespace std;typedef int datetype;struct listnode      {DateType _date;      ListNode* _next;     //precursor pointer listnode* _prev;    //rear drive pointer ListNode (DATETYPE&NBSP;X)   //initialization of the node: _date (x),  _next (null),  _prev (null) {}};class list{public:      list ()        //constructor: _head (null),  _tail (null) {}~List ( )    //destructor {Clear ();} Void pushback (datetype x)    //tail interpolation {if  (_head == null) {_head =  _tail = new listnode (x);} Else{listnode* tmp = new listnode (x); _tail->_next = tmp;tmp->_prev =  _tail;_tail = tmp;}} Void clear ()        //empty linked list {Listnode* cur = _head;while   (cur) {listnode* d El = cur;cur = cur->_next;delete del;}} Void printflist ()      //Print List {listnode* cur = _head;while  ( cur) {cout << cur->_date <<  "--"; cur = cur->_next;} cout <<  "null " &NBSP;&LT;&LT;&NBSP;ENDL;} Void popback ()      //tail {if  (_head==null) {return;}  else if (_head->_next==null) { delete _head; _head = _tail =  NULL;}  else { listnode* cur = _tail->_prev; delete _tail; _tail  = cur; cur->_next = null; }}void pushfront (DateType x)      //head interpolation method {if  (_head == null) {_head = _tail = new listnode (x);} Else{listnode* tmp = new listnode (x);tmp->_next = _head;_head->_prev  = tmp;_head =&nbSp;tmp;}} Void popfront ()      //head departure {if  (_head == _tail) {if  (_head) { Delete _head;_head = _tail = null;}} Else{listnode* cur = _head->_next;delete _head;_head = cur;cur->_prev  = null;}} Void insert (listnode* pos, datetype x)      //inserts a number {if  (_ Head == _tail) {if  (_head) {listnode* tmp = new listnode (x);p Os->_next  = tmp;tmp->_prev = pos;} Else{_head = _tail = new listnode (x);}} else if  (pos->_next == null) {listnode* tmp = new listnode (x); tmp- >_next = null;tmp->_prev = pos;pos->_next = tmp;} Else{listnode* tmp = new listnode (x);    tmp->_next =  Pos->_next;pos->_next->_prev = tmp;tmp->_prev&nbSp;= pos;pos->_next = tmp;}} Listnode* find (datetype x)    //looks for a number and returns the address of that node {listnode* cur = _head; while  (  (cur->_date != x)  &&  (cur != null)  ) {cur  = cur->_next;} Return cur;} Void erase (listnode*  pos )   //Delete a node {if  (!pos) {return;} else if  (pos->_prev == null) {if  (pos->_next) {listnode* next =  Pos->_next;    delete pos;next->_prev = null;_head = next;} Else{pos->_next = null;pos->_prev = null;delete pos;}} else if  (pos->_next == null) {listnode* prev = pos->_prev;delete  Pos;prev->_next = null;} else{listnode* prev = pos->_prev; Listnode* next = pos->_next;delete pos;prev->_next = next;next->_Prev = prev;}          }private:ListNode* _head; listnode* _tail;};

This article is from the "0-point Time" blog, please make sure to keep this source http://10741764.blog.51cto.com/10731764/1747567

Implementation of basic functions in doubly linked list