【Linux 完整测试代码】数据结构之双向链表 _链表

别摸鱼啦，说的就是你，学习编程从入门到放弃。掌握编程思维方式，远胜于死记硬背编程语法，不能再迷路了。
双向链表
图一双向链表结构示意图
图二双向链表创建流程示意图
为了清晰的理解双向链表的创建操作，请参考链表创建流程示意图。以下为双向链表创建步骤解析
/* 1. 当前节点的nextNode指向newNode 2. newNode的previoueNode指向currentNode3. newNode的nextNode指向nullptr防止出现野指针4. currentNode指向新创建的节点(newNode)*/currentNode->nextNode = staffInfo;newNode->previousNode = currentNode;newNode->nextNode = nullptr;currentNode = newNode;
双向链表的操作比较常见，肯定难不倒机智的小伙伴，咱们就直接进阶到双向循环链表一探究竟啦
【【Linux 完整测试代码】数据结构之双向链表】双向循环链表
图三双向链表结构示意图
双向循环链表创建操作
双向循环链表的核心思想是双向、循环，也就是说要能够双向操作并且形成闭环，图文详解双向循环链表创建过程：
1. 新建节点
2. 头节点的指向
3. 和互相指向
4. 的指向头节点
第五步指向, 至此双向、循环完成闭环
/* 1. 头节点previousNode指向newNode 2. 当前节点的nextNode指向newNode 3. newNode的previoueNode指向currentNode3. newNode的nextNode指向头节点4. currentNode指向新创建的节点(newNode)*/headerNode->previousNode = newNode;currentNode->nextNode = newNode;newNode->previousNode = currentNode;newNode->nextNode = headerNode;currentNode = newNode;
双向循环链表创建核心代码
为防止出现野指针需要将尾部node的指向
myData* headerNode, *currentNode;void DoubleLinkedList::createLinkedList(){myData* newNode = new myData{0};if (!headerNode && !currentNode) {headerNode = currentNode = newNode;} else {headerNode->previousNode = newNode;currentNode->nextNode = newNode;newNode->previousNode = currentNode;newNode->nextNode = headerNode;currentNode = newNode;}}
双向链表的插入操作也是个技术活，下面开始图文并茂，注意有细节哦
1.找到要插入的节点位置
2. 注意点来了，划重点要考的
3. 最后一步的指向

文章插图
双向循环链表的插入操作
图四双向链表插入流程示意图

myData *newNode = new myData;newNode->nextNode = myNode->nextNode;myNode_1 = myNode->nexNode;myNode_1->previousNode = newNode;myNode->nextNode = newNode;

双向循环链表的遍历操作
双向循环链表可以从正反两个方向进行数据遍历，咱们就直接开始双向遍历了哈
主要是先找到, 每次遍历需要先判断是不是尾部节点（的是不是指向了头节点）如果不是尾部节点，直接将指向的下一个节点，如果是尾部节点，就开始反向遍历

bool isBackwardsEcho = false;/* 是否遍历到了尾部节点 */if (currentNode->nextNode == headerNode &&headerNode->previousNode == currentNode)isBackwardsEcho = true;/* 反向遍历 */if (isBackwardsEcho) {/* 是否反向遍历到了头部节点 */(currentNode == headerNode) ?(currentNode = nullptr):(currentNode = currentNode->previousNode);} else /* 正向遍历 */currentNode = currentNode->nextNode;

双向循环链表的删除操作
双向循环链表的删除操作，也有细节点需要注意，可以参考下面的代码逻辑

myData::~myData() {/* 析构函数 进行一些内存释放等操作 */}myData * p = headerNode;this->currentNode = headerNode;while (currentNode) {/* 是否只有一个节点 */if (currentNode->nextNode == nullptr) { delete currentNode;currentNode = headerNode = nullptr;/* 不是尾部节点*/} else if (currentNode->nextNode != p) {currentNode = currentNode->nextNode;delete headerNode;headerNode = currentNode;/* 是尾部节点 */} else if (currentNode->nextNode == p) {delete currentNode;currentNode = headerNode = nullptr;}}

呈上双向链表的完整示例代码，供给小伙伴学习交流，赶紧 ctrl-c ctrl-v 测试一下吧

/********************************************************* Description: simply C++ linked demo* Author: jiangxiaoyu* Data: Fir Apr 28 2023*********************************************************/#include #include #include #include #include typedef struct StaffInfo {intages;intsalary;intseniority;std::stringname;std::stringpost;std::stringeducation;void *previousNode;void *nextNode;~StaffInfo();} StaffInfomation;StaffInfo::~StaffInfo() {ages = salary = seniority = 0;name = post = education = "";previousNode = nextNode = nullptr;}class DoubleLinkedList {public:DoubleLinkedList();void helper();bool isRegexInput(std::string str);std::string regexDigit(std::string str, std::string msg);void createLinkedList();void collectStaffInfomation(StaffInfomation *);void printStaffInfomation();void destoryStaffInfomation();void exitSystem();private:StaffInfomation* headerNode,* currentNode;};/* initialize member */DoubleLinkedList::DoubleLinkedList():headerNode(nullptr),currentNode(nullptr) {}void DoubleLinkedList::helper(){std::cout << "\n\n" << std::endl;std::cout << "Simply staff information manager syatem" << std::endl;std::cout << "1) Create New Staff Information" << std::endl;std::cout << "2) Printf All Staff Information" << std::endl;std::cout << "3) Destory All Staff Information" << std::endl;std::cout << "4) Helper Manual" << std::endl;std::cout << "5) Exit" << std::endl;}void DoubleLinkedList::collectStaffInfomation(StaffInfomation * staffInfo){std::cout << "-------------------------------" << std::endl;std::cout << "staff information system" << std::endl;std::cout << "\nstaff name:"; std::cin >> staffInfo->name;std::cout << "\nstaff ages:"; std::cin >> staffInfo->ages;std::cout << "\nstaff education:"; std::cin >> staffInfo->education;std::cout << "\nstaff post:"; std::cin >> staffInfo->post;std::cout << "\nstaff seniority:"; std::cin >> staffInfo->seniority;std::cout << "\nstaff salary:"; std::cin >> staffInfo->salary;}void DoubleLinkedList::printStaffInfomation(){StaffInfomation * LinkedHeader = headerNode;bool isBackwardsEcho = false;while (LinkedHeader) {std::cout << "-------------------------------" << std::endl;std::cout << "\tstaff information system" << std::endl;printf("\tstaff name:%s\n",LinkedHeader->name.data());printf("\tstaff ages:%d\n",LinkedHeader->ages);printf("\tstaff education:%s\n",LinkedHeader->education.data());printf("\tstaff post:%s\n",LinkedHeader->post.data());printf("\tstaff seniority:%d\n",LinkedHeader->seniority);printf("\tstaff salary:%d\n",LinkedHeader->salary);std::cout << "-------------------------------" << std::endl;if (LinkedHeader->nextNode == headerNode && headerNode->previousNode == LinkedHeader) {isBackwardsEcho = true;std::cout << "=========== already traverse list =============" << std::endl;}/* backwards traverse */if (isBackwardsEcho) {/* backwards traverse all list or not */(LinkedHeader == headerNode) ?(LinkedHeader = nullptr):(LinkedHeader = (StaffInfomation*)LinkedHeader->previousNode);} else LinkedHeader = (StaffInfomation *)LinkedHeader->nextNode;}}void DoubleLinkedList::createLinkedList(){StaffInfomation * staffInfo = new StaffInfomation{0};if (!headerNode && !currentNode) {headerNode = currentNode = staffInfo;} else {headerNode->previousNode = staffInfo;currentNode->nextNode = staffInfo;staffInfo->previousNode = currentNode;staffInfo->nextNode = headerNode;currentNode = staffInfo;}collectStaffInfomation(staffInfo);}void DoubleLinkedList::destoryStaffInfomation(){StaffInfomation * p = headerNode;this->currentNode = headerNode;while (currentNode) {if (currentNode->nextNode == nullptr) { /* if only one node */delete currentNode;currentNode = headerNode = nullptr;} else if (currentNode->nextNode != (StaffInfomation*)p) {currentNode = (StaffInfomation*)currentNode->nextNode;delete headerNode;headerNode = currentNode;} else if ((StaffInfomation*)currentNode->nextNode == (StaffInfomation*)p) { /* if travse */delete currentNode;currentNode = headerNode = nullptr;}}}int main(int argc, char ** argv){DoubleLinkedList test;do {test.helper();int cmd = 0; std::cout << "please input flag:"; std::cin >> cmd;switch (cmd) {case 1: test.createLinkedList(); break;case 2: test.printStaffInfomation(); break;case 3: test.destoryStaffInfomation(); break;case 4: test.helper(); break;default: std::cout << "input invalid!" << std::endl;}} while(true);return 0;}

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