C + + implements common functions of doubly linked list

struct definition Struct node{node (const datatype& d): _next (null), _prev (null), _data (d) {}public:d atatype _data; node* _prev; node* _next;};/ /bidirectional linked list class definition class doulist{friend ostream& operator<< (ostream& os, doulist &AMP;&NBSP;L);p ublic:doulist ()//constructor: _head (null), _tail (null) {}doulist (const doulist& l)//copy construct {if   (l._head == null) {return;} node *cur = l._head; Node *newnode = new node (Cur->_data);_head = newnode;_tail = _head; cur = cur->_next;while  (cur) {newnode = new node (cur->_data); _tail->_ next = newnode;newnode->_prev = _tail;_tail = newnode;cur = cur- >_next;}} Overloads of the Doulist& operator= (doulist l)//= operator {swap (_head,l._head); swap (_tail, l._tail); return  *this;} ~doulist ()//destructor {node* cur = _head;while  (cur) {node* del =&Nbsp;cur;cur = cur->_next;delete del;} _head = null;_tail = null;} Public:void pushback (const datatype& d);//post-insertion void popback ();//After Void pushfront ( Const datatype& d Void popfront ()//Pre-node* find (const datatype& d) ;//Find Void insert (NODE*&NBSP;POS,&NBSP;CONST&NBSP;DATATYPE&AMP;&NBSP;D);//Insert Void bubbsort () in the specified position;// Bubble sort void reverse ();//Reverse Void remove (CONST&NBSP;DATATYPE&AMP;&NBSP;D);//delete the specified element Void removeall ( CONST&NBSP;DATATYPE&AMP;&NBSP;D);//delete all specified elements void erase (node* pos);//delete the specified node Private:node* _head ;//head pointer node* _tail;//tail pointer};ostream& operator<< (ostream& os, doulist&  L)//Overload {node* cur = l._head;while  (cur) of the output operator {os << cur->_data < <  "<=>"; cur = cur->_next;} cout <<  "over"; return os;} Void doulist::P ushback (CONST&NBSp;datatype& d) {Node* newnode = new node (d);if  (_head == NULL) {_ Head = newnode;_tail = _head;} Else{_tail->_next = newnode;newnode->_prev = _tail;_tail = newnode;}} Void doulist::P opback () {if  (_head == null) {return;} if  (_head == _tail) {Delete _head;_head = null;_tail = null;return;} Node* del = _tail;_tail = _tail->_prev;_tail->_next = null;delete  del;} Void doulist::P Ushfront (const datatype& d) {node* newnode = new node (d); if  (_head == null) {_head = newnode;_tail = _head;} Else{newnode->_next = _head;_head->_prev = newnode;_head = newnode;}} Void doulist::P Opfront () {if  (_head == null) {return;} if  (_head == _tail) {delete _head;_head =  Null;_tail = null;return;} Node* del = _head;_head = _head->_next;_head->_prev = null;delete  del;} Node* doulist::find (const datatype& d) {node* cur = _head;while  (cur) {if   (cur->_data == d) {return cur;} Cur = cur->_next;} Return null;} Void doulist::insert (node* pos, const datatype& d) {if  (Pos == NULL ) {return;} Node* newnode = new node (d);if  (Pos != _tail)//Non-tailed node insert {newNode->_next  = pos->_next;newnode->_prev = pos;pos->_next = newnode;} else//tail node Insert {_tail->_next = newnode;newnode->_prev = _tail;_tail = newnode;}} Void doulist::bubbsort () {node* cur = _head; node* end = null;bool flag = true;while  (cur->_next != end  && flag) {FLag = false;while  (cur->_next != end && cur) {if  (cur->_ Data > cur->_next->_data) {Flag = true;swap (cur->_data, cur->_next-> _data);} Cur = cur->_next;} End = cur;cur = _head;}} Void doulist::reverse () {node* cur = _head; node* newhead = null; node* tmp = null;while  (cur) {tmp = cur->_next;cur->_next =  newhead;if  (newhead) {newhead->_prev = cur;} Newhead = cur;newhead->_prev = null;cur = tmp;} Swap (_head, _tail);} Void doulist::remove (const datatype& d) {if  (_head == null)//No node {return;} node* cur = _head;while  (cur) {if  (cur->_data == d) {if  (cur ==  _head)//First equal {Popfront (); return;} else if  (cur == _tail&& _head != _tail)//Last node equal {popback (); return;} else//Other Nodes {Cur->_prev->_next = cur->_next;cur->_next->_prev = cur->_prev ;d Elete cur;return;}} Cur = cur->_next;}} Void doulist::removeall (const datatype& d) {Node* cur = _head;bool flag  = true;while  (cur) {flag = true;if  (cur->_data == d) {flag =  false;cur = cur->_next; Remove (d); if  (flag) {Cur = cur->_next;}}} Void doulist::erase (Node* pos) {if  (Pos == null)//{return;} if  (pos == _head)//Delete first node {popfront (); return;} if  (pos == _tail)//Delete last node {popback (); return;} Deletion of non-tailed nodes pos->_next->_prev = pos->_prev;pos->_prev->_next = pos->_next;}

C + + implements common functions of doubly linked list