The underlying operation of a doubly linked list (C + + implementation)

★c++ implementing the underlying operation of a doubly linked list (implementation of the Class)

#include <iostream> #include <cassert>using namespace std;typedef int DataType; class double_link_list{                         //defines a doubly linked list class, including bidirectional precursors and successors, and the initialization of objects to public: Friend class listnode;double_link_list (datatype x = 0): _data (x), _next (NULL), _prev ( NULL) {}private:double_link_list* _prev;double_link_list* _next;datatype _data;}; class listnode{public:        //Note the Friend keyword in the previous category, friend function, Otherwise, the class cannot access the private member of its class ListNode ()      //constructor: _head (null), _tail (null) {}~listnode ()//destructor { Clear ();//Purge function}listnode (const listnode& list)         // Copy constructor {double_link_list *cur = list._head;while  (cur) {pushback (cur->_data);}} listnode operator =  (listnode list)     //assignment operator overloaded function {double_link_list *cur = list._head;while  (cur) {PushBack (cur- >_data);}} public://Void pushback (const datatype& x);//tail delete void popback ();//head plug Void pushfront (const datatype& x);//First delete void popfront ();//Specify location to insert node Void insert (double_link_list*  POS,&NBSP;CONST&NBSP;DATATYPE&AMP;&NBSP;X);//Find node function Double_link_list* find (const datatype& x );//delete node function void erase (const datatype& x);//Inverse list function void reverse ();//Output function Void print () ;p rivate:void clear () {while  (_head) {double_link_list* cur = _head;_head = _ Head->_next;delete cur;}} double_link_list *_head;double_link_list *_tail;};/ /tail plug Void listnode::P ushback (const datatype&x)     //Note the addition of domain modifiers, otherwise you have to define {if in the class body   (_head == null) {_tail = _head = new double_link_list (x); _head->_ Next = nuLl;_head->_prev = null;} Else{_tail->_next = new double_link_list (x); _tail->_next->_prev = _tail;_ Tail = _tail->_next;}} Head plug Void listnode::P ushfront (const datatype&x) {double_link_list* cur = new  Double_link_list (x);if  (_head == null) {_tail = _head = cur;} Else{cur->_next = _head;cur->_next->_prev = cur;_head = cur;}} Tail Delete void listnode::P opback () {if  (_tail) {double_link_list *cur = _tail;_tail =  _tail->_prev;_tail->_next = null;delete cur;}} Head deletion void listnode::P opfront () {if  (_head) {double_link_list *cur = _head;_head =  _head->_next;_head->_prev = null;delete cur;}} Specifies the location of the insertion node Void listnode::insert (double_link_list* pos, const datatype& x) {assert ( _head);d ouble_link_list *cur = _head;while  (cur) {if  (cur == pos) {if  (cur == _tail) {PushBack (x);} Else{double_link_list *tmp = new double_link_list (x); tmp->_next = cur->_ Next;tmp->_prev = cur;tmp->_next->_prev = tmp;cur->_next = tmp;} return;} Cur = cur->_next;}} Finds the specified node Double_link_list* listnode::find (const datatype& x) {double_link_list* cur  = _head;while  (cur) {if  (cur->_data == x) return cur;cur = cur- >_next;} Return null;} Delete a node void listnode::erase (const datatype &x) {double_link_list *cur = _ head;while  (cur) {if  (cur->_data == x) {double_link_list* tmp = cur;cur- >_prev->_next = cur->_next;cur->_next->_prev = cur->_prev;cur =  cur->_next;delete tmp;}}} Inverse doubly linked list void listnode::reverse () {STD:: Swap (_head, _tail);d ouble_link_list* cur = _head;while  (cur) {Std::swap (cur->_ Next, cur->_prev); cur = cur->_next;}} Output doubly linked list Void listnode::P rint () {double_link_list* cur = _head;while  (cur) {cout  << cur->_data <<  "Cur = cur->_next"; cout <<  "NULL" &NBSP;&LT;&LT;&NBSP;ENDL;}

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The underlying operation of a doubly linked list (C + + implementation)