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The structure of leading two-way cyclic linked list

In fact, single linked lists also have a big drawback:

1. You can't traverse from back to front.

two。 Unable to find the precursor

In addition to the single linked list, we naturally have a two-way linked list, what we want to say is to take the lead in the two-way circular linked list, simply understood as: the lead node, there are two directions. Cyclical. The structure diagram is as follows:

Although the structure is more complex, it is very convenient for us to find the node, for example, we can find the tail node directly, and then enter the related operation. The operation of the actual code will be simpler and more convenient than the single linked list. Without too much explanation here, we will start with the code directly.

Code operation

Let's go straight to the point and get into the operation of the code implementation, and if you understand the previous operation, I'm sure it won't be difficult for you. The source code is given directly below:

List.h

# pragma once#include # include typedef int LTDataType;// takes the lead in bidirectional loop-the optimal linked list structure. Inserting and deleting data anywhere is O (1) typedef struct listNode {struct ListNode* next; struct ListNode* prev; LTDataType data;} ListNode;// initializing ListNode*ListInit (); / / destroying void ListDestory (ListNode* phead); / / printing void ListPrint (ListNode* phead) / / insert void ListPushBack (ListNode* phead, LTDataType x); / / insert void ListPushFront (ListNode* phead, LTDataType x); / / insert void ListPopFront (ListNode* phead); / / delete void ListPopBack (ListNode* phead); ListNode* ListFind (ListNode* phead, LTDataType x); / / insert xvoid ListInsert (ListNode* pos, LTDataType x) before pos position; / / delete the value void ListErase (ListNode* pos) of pos position

List.c

# include "List.h" / / Open up a new node ListNode* BuyListNode (LTDataType x) {ListNode* newnode = (ListNode*) malloc (sizeof (ListNode)); newnode- > data = x; newnode- > next = NULL; newnode- > prev = NULL; return newnode;} / / initialize ListNode* ListInit () {ListNode*phead = BuyListNode (0); phead- > next = phead; phead- > prev = phead Return phead;} / / destroy void ListDestory (ListNode* phead) {assert (phead); ListNode* cur = phead- > next; while (cur! = phead) {ListNode* next = cur- > next; free (cur); cur = next;} free (phead); phead = NULL } / / print void ListPrint (ListNode* phead) {ListNode* cur = phead- > next; while (cur! = phead) {printf ("% d", cur- > data); cur = cur- > next;} printf ("\ n");} / / void ListPushBack (ListNode* phead, LTDataType x) {assert (phead); ListNode* tail = phead- > prev ListNode* newnode = BuyListNode (x); tail- > next = newnode; newnode- > prev = tail; newnode- > next = phead; phead- > prev = newnode;} / / void ListPushFront (ListNode* phead, LTDataType x) {assert (phead); ListNode* first = phead- > next; ListNode* newnode = BuyListNode (x); newnode- > next = first; first- > prev = newnode Phead- > next = newnode; newnode- > prev = phead;} / / head deletion void ListPopFront (ListNode* phead) {assert (phead); assert (phead- > next! = phead); ListNode* first = phead- > next; ListNode* second = first- > next; phead- > next = second; second- > prev = phead; free (first); first = NULL } / / delete void ListPopBack (ListNode* phead) {assert (phead); assert (phead- > next! = phead); ListNode* tail = phead- > prev; ListNode* prev = tail- > prev; prev- > next = phead; phead- > prev = prev; free (tail); tail = NULL;} ListNode* ListFind (ListNode* phead, LTDataType x) {assert (phead); ListNode* cur = phead- > next While (cur! = phead) {if (cur- > data = = x) {return cur;} cur = cur- > next;} return NULL;} / / insert xvoid ListInsert (ListNode* pos, LTDataType x) {assert (pos) before the pos location ListNode* prev = pos- > prev; ListNode* newnode = BuyListNode (x); prev- > next = newnode; newnode- > prev = prev; newnode- > next = pos; pos- > prev = newnode;} / / remove the value of the pos location void ListErase (ListNode* pos) {assert (pos); ListNode* prev = pos- > prev; ListNode* next = pos- > next; prev- > next = next Next- > prev = prev; free (pos);}

Test.c

# include "List.h" void TestList1 () {ListNode* plist = ListInit (); ListPushBack (plist, 1); ListPushBack (plist, 2); ListPushBack (plist, 3); ListPushBack (plist, 4); ListPrint (plist); ListPushFront (plist, 0); ListPushFront (plist,-1); ListPrint (plist); ListPopFront (plist); ListPopFront (plist) ListPopFront (plist); ListPrint (plist); ListPopBack (plist); ListPrint (plist);} void TestList2 () {ListNode* plist = ListInit (); ListPushBack (plist, 1); ListPushBack (plist, 2); ListPushBack (plist, 3); ListPushBack (plist, 4); ListPrint (plist); ListNode* pos = ListFind (plist, 3) If (pos) {pos- > data * = 10; printf ("found and * 10\ n");} else {printf ("not found\ n");} ListPrint (plist); ListInsert (pos, 300); ListPrint (plist); ListErase (pos) ListPrint (plist);} int main () {TestList2 (); return 0;} the above is about the content of this article "how to realize the two-way circular linked list led by C language". I believe everyone has a certain understanding. I hope the content shared by the editor will be helpful to you. If you want to know more about the relevant knowledge, please follow the industry information channel.

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