循环链表 -- c语言实现

#pragma once
// 带头+双向+循环链表增删查改实现
#include<stdlib.h>
#include<stdio.h>
#include<assert.h>typedef int LTDataType;typedef struct ListNode
{LTDataType data;struct ListNode* next;struct ListNode* prev;
}ListNode;//双链表申请一个新节点
ListNode* BuyListNode(LTDataType x);// 创建返回链表的头结点
ListNode* ListCreate();// 双向链表打印
void ListPrint(ListNode* pHead);// 双向链表尾插
void ListPushBack(ListNode* pHead, LTDataType x);// 双向链表尾删
void ListPopBack(ListNode* pHead);// 双向链表头插
void ListPushFront(ListNode* pHead, LTDataType x);// 双向链表头删
void ListPopFront(ListNode* pHead);// 双向链表查找
ListNode* ListFind(ListNode* pHead, LTDataType x);// 双向链表在pos的前面进行插入
void ListInsert(ListNode* pos, LTDataType x);// 双向链表删除pos位置的节点
void ListErase(ListNode* pos);// 双向链表销毁
void ListDestory(ListNode* pHead);//双链表申请一个新节点
ListNode* BuyListNode(LTDataType x)
{ListNode* node = (ListNode*)malloc(sizeof(ListNode));if (node == NULL){perror("BuyListNode::malloc");return NULL;}node->data = x;node->next = NULL;node->prev = NULL;return node;
}// 创建返回链表的头结点
ListNode* ListCreate()
{ListNode* head = BuyListNode(-1);head->next = head;head->prev = head;
}// 双向链表打印
void ListPrint(ListNode* pHead)
{assert(pHead);ListNode* cur = pHead->next;printf("head<=>");while (cur != pHead){printf("%d<=>", cur->data);cur = cur->next;}printf("\n");return;
}// 双向链表尾插
// void ListPushBack(ListNode* pHead, LTDataType x)
// {
// 	assert(pHead);
// 	ListNode* newnode = BuyListNode(x);
// 	ListNode* tail = pHead->prev;
// 	tail->next = newnode;
// 	newnode->prev = tail;
// 	newnode->next = pHead;
// 	pHead->prev = newnode;
// 	return;
// }
// 下面的写法更容易理解
void ListPushBack(ListNode* pHead, LTDataType x)
{assert(pHead);ListNode* newnode = BuyListNode(x);newnode->next = pHead;newnode->prev = pHead->prev;pHead->prev->next = newnode;pHead->prev = newnode;return;}// 双向链表尾删
void ListPopBack(ListNode* pHead)
{assert(pHead);ListNode* tail = pHead->prev;if (tail == pHead)return;tail->prev->next = pHead;pHead->prev = tail->prev;free(tail);tail = NULL;return;
}// 双向链表头插
// void ListPushFront(ListNode* pHead, LTDataType x)
// {
// 	assert(pHead);
// 	ListNode* newnode = BuyListNode(x);
// 	newnode->next = pHead->next;
// 	pHead->next->prev = newnode;
// 	pHead->next = newnode;
// 	newnode->prev = pHead;
// 	return;
// }void ListPushFront(ListNode* pHead, LTDataType x)
{assert(pHead);ListNode* newnode = BuyListNode(x);newnode->next = pHead->next;newnode->prev = pHead;pHead->next->prev = newnode;pHead->next = newnode;return;
}// 双向链表头删
void ListPopFront(ListNode* pHead)
{assert(pHead);ListNode* tmp = pHead->next;if (tmp == pHead)return;tmp->next->prev = pHead;pHead->next = tmp->next;free(tmp);tmp = NULL;
}// 双向链表查找
ListNode* ListFind(ListNode* pHead, LTDataType x)
{assert(pHead);ListNode* cur = pHead;while (cur->data != x){cur = cur->next;if (cur == pHead)return NULL;}return cur;
}// 双向链表在pos的前面进行插入
// void ListInsert(ListNode* pos, LTDataType x)
// {
// 	assert(pos);
// 	ListNode* newnode = BuyListNode(x);
// 	pos->prev->next = newnode;
// 	newnode->prev = pos->prev;
// 	pos->prev = newnode;
// 	newnode->next = pos;
// 	return;
// }
// 下面这个更好理解，且避免了pos为头节点时若头节点的 next 为 NULL 时的错误
void ListInsert(ListNode* pos, LTDataType x)
{assert(pos);ListNode* newnode = BuyListNode(x);newnode->next = pos;newnode->prev = pos->prev;pos->prev->next = newnode;pos->prev = newnode;return;
}// 双向链表删除pos位置的节点
void ListErase(ListNode* pos)
{assert(pos);pos->prev->next = pos->next;pos->next->prev = pos->prev;free(pos);pos = NULL;return;
}// 双向链表销毁
void ListDestory(ListNode* pHead)
{assert(pHead);ListNode* cur = pHead->next;while (cur != pHead){ListNode* tmp = cur->next;free(cur);cur = tmp;}free(pHead);return;
}int main() {// 创建一个双向循环链表,头节点headListNode* myList = ListCreate();// 尾插元素ListPushBack(myList, 1);ListPushBack(myList, 2);ListPushBack(myList, 3);// 头插元素ListPushFront(myList, 0);// 打印链表ListPrint(myList); // 应该输出：head<=>0<=>1<=>2<=>3<=>// 查找元素ListNode* foundNode = ListFind(myList, 2);if (foundNode != NULL) {printf("找到的节点的data: %d\n", foundNode->data); // 应该输出：Found node with value: 2} else {printf("没有找到\n");}// 在指定位置前插入元素ListInsert(foundNode, 10);// 打印链表ListPrint(myList); // 应该输出：head<=>0<=>1<=>10<=>2<=>3<=>// 删除指定位置的元素ListErase(foundNode);// 打印链表ListPrint(myList); // 应该输出：head<=>0<=>1<=>10<=>3<=>// 头删元素ListPopFront(myList);// 尾删元素ListPopBack(myList);// 打印链表ListPrint(myList); // 应该输出：head<=>1<=>2<=>// 打印 head 的 prev 的 dataprintf("head->prev->data: %d", myList->prev->data);// 销毁链表ListDestory(myList);return 0;
}

运行结果：