Implementation of two-way linked list in C ++

A two-way linked list adds a forward link based on a one-way linked list. Many of the processing methods are similar. For example, you can find the length of a linked list or a node. All similar parts are not implemented one by one. If you are interested, refer to the previous blog. The following two-way linked list is implemented in VC6 ). Correct the error. 1. Code Organization 2. dll. h dual-chain table and node description

# Ifndef _ DLL_H _ # define dataType int # define endOfData 0 class node {public: dataType data; // node data node * next; // backward pointer (close to the end node) node * pre; // forward pointer (close to the head)}; class dll {public: dll ();~ Dll (); void create (); // construct a two-way linked list void print (); // print the linked list bool insert (int pos, dataType num ); // Insert the num node in the position pos. return true if the insertion is complete; otherwise, return false void del (dataType num); // Delete All num nodes in the linked list private: int getLength (); // obtain the number of nodes contained in the linked list node * head; // The linked list header pointer}; # endif

 

3. dll. cpp double-linked table functions

# Include <iostream> # include "dll. h" using namespace std; dll: dll () {head = NULL;} dll ::~ Dll () {node * ptrNode = head; node * ptrNodeTmp = NULL; while (ptrNode! = NULL) {ptrNodeTmp = ptrNode-> next; delete ptrNode; ptrNode = ptrNodeTmp ;}} void dll: create () {// The first node * ptrNode = new node; ptrNode-> pre = NULL; ptrNode-> data = endOfData; head = ptrNode; bool firstNode = true; // whether it is the first node dataType num = endOfData; while (1) {cout <"enter a node data:"; cin> num; if (num = endOfData) {ptrNode-> next = NULL; break ;} if (firstNode = false) // all subsequent nodes require new node {nod E * ptrNodeTmp = new node; ptrNodeTmp-> data = num; ptrNode-> next = ptrNodeTmp; ptrNodeTmp-> pre = ptrNode; ptrNode = ptrNodeTmp;} if (firstNode = true) // The first node does not need new node {ptrNode-> data = num; firstNode = false; }}if (head-> data = endOfData) // No data exists in the linked list, you need to delete the first node {delete head; head = NULL ;}} void dll: print () {node * ptrNode = head; while (ptrNode! = NULL) {cout <ptrNode-> data <""; ptrNode = ptrNode-> next;} cout <endl;} int dll: getLength () {node * ptrNode = head; int num = 0; while (ptrNode! = NULL) {num ++; ptrNode = ptrNode-> next;} return num;} bool dll: insert (int pos, dataType num) {if (pos <0 | pos> = getLength () // The inserted pos is incorrect (0-getLength ()-1) {return false ;} // find the pointer to the pos to be inserted and the next pointer node * ptrNodeAhead = head; node * ptrNodeFellow = NULL; int count = 0; while (1) {if (count ++ = pos) break; ptrNodeFellow = ptrNodeAhead; ptrNodeAhead = ptrNodeAhead-> next;} node * ptr = new node; ptr-> Data = num; ptr-> pre = ptrNodeFellow; ptr-> next = ptrNodeAhead; if (ptrNodeFellow! = NULL) // not the insert header node {ptrNodeFellow-> next = ptr;} else // The insert header node. The head must be changed to {head = ptr ;} ptrNodeAhead-> pre = ptr; return true;} void dll: del (dataType num) {node * ptrNodeAhead = head; // ptrNodeAhead points to the node to be deleted * ptrNodeFellow = NULL; // ptrNodeFellow points to the previous node (node closest to the head) of the node to be deleted while (ptrNodeAhead! = NULL) {while (ptrNodeAhead-> data! = Num & ptrNodeAhead-> next! = NULL) // locate the num node or end the search {ptrNodeFellow = ptrNodeAhead; ptrNodeAhead = ptrNodeAhead-> next;} if (ptrNodeAhead-> data = num) // find the num node {node * ptrNode = ptrNodeAhead-> next; if (ptrNodeAhead! = Head) // not delete the header node {ptrNodeFellow-> next = ptrNode;} else // Delete the header node. Note the head pointer value {head = ptrNodeAhead-> next ;} if (ptrNodeAhead-> next! = NULL) // not delete the end node {ptrNode-> pre = ptrNodeFellow;} delete ptrNodeAhead; // release the num node ptrNodeAhead = ptrNode ;} else // search end {ptrNodeAhead = NULL ;}}}

 

4. mian. cpp Test File

# Include <iostream> # include "dll. h "using namespace std; int main () {dll exp; // create a linked list and print exp. create (); exp. print (); // insert 99999 in position 2 and print exp. insert (2,99999); exp. print (); // Delete the node at location 2 and print exp. del (2); exp. print (); return 0 ;}