c语言双向链表插入和删除完整代码

以下是双向链表的插入和删除完整代码示例，包括头插法、尾插法、指定位置插入和删除等操作：

#include <stdio.h>
#include <stdlib.h>

// 双向链表节点结构体
typedef struct Node {
    int data;
    struct Node* prev;
    struct Node* next;
} Node;

// 双向链表结构体
typedef struct List {
    int length;
    struct Node* head;
    struct Node* tail;
} List;

// 初始化双向链表
void initList(List* list) {
    if (list == NULL) {
        return;
    }
    list->length = 0;
    list->head = NULL;
    list->tail = NULL;
}

// 创建双向链表节点
Node* createNode(int data) {
    Node* node = (Node*)malloc(sizeof(Node));
    if (node == NULL) {
        return NULL;
    }
    node->data = data;
    node->prev = NULL;
    node->next = NULL;
    return node;
}

// 头插法插入节点
void insertAtHead(List* list, int data) {
    Node* node = createNode(data);
    if (list->head == NULL) {
        list->head = node;
        list->tail = node;
    } else {
        node->next = list->head;
        list->head->prev = node;
        list->head = node;
    }
    list->length++;
}

// 尾插法插入节点
void insertAtTail(List* list, int data) {
    Node* node = createNode(data);
    if (list->tail == NULL) {
        list->head = node;
        list->tail = node;
    } else {
        node->prev = list->tail;
        list->tail->next = node;
        list->tail = node;
    }
    list->length++;
}

// 在指定位置插入节点
void insertAtIndex(List* list, int index, int data) {
    if (index < 0 || index > list->length) {
        return;
    }
    if (index == 0) {
        insertAtHead(list, data);
        return;
    }
    if (index == list->length) {
        insertAtTail(list, data);
        return;
    }
    Node* node = createNode(data);
    Node* cur = list->head;
    for (int i = 0; i < index - 1; i++) {
        cur = cur->next;
    }
    node->prev = cur;
    node->next = cur->next;
    cur->next->prev = node;
    cur->next = node;
    list->length++;
}

// 删除头节点
void deleteAtHead(List* list) {
    if (list->head == NULL) {
        return;
    }
    Node* node = list->head;
    list->head = node->next;
    if (list->head != NULL) {
        list->head->prev = NULL;
    } else {
        list->tail = NULL;
    }
    free(node);
    list->length--;
}

// 删除尾节点
void deleteAtTail(List* list) {
    if (list->tail == NULL) {
        return;
    }
    Node* node = list->tail;
    list->tail = node->prev;
    if (list->tail != NULL) {
        list->tail->next = NULL;
    } else {
        list->head = NULL;
    }
    free(node);
    list->length--;
}

// 删除指定位置节点
void deleteAtIndex(List* list, int index) {
    if (index < 0 || index >= list->length) {
        return;
    }
    if (index == 0) {
        deleteAtHead(list);
        return;
    }
    if (index == list->length - 1) {
        deleteAtTail(list);
        return;
    }
    Node* cur = list->head;
    for (int i = 0; i < index; i++) {
        cur = cur->next;
    }
    cur->prev->next = cur->next;
    cur->next->prev = cur->prev;
    free(cur);
    list->length--;
}

// 打印双向链表
void printList(List* list) {
    if (list == NULL || list->head == NULL) {
        return;
    }
    Node* cur = list->head;
    while (cur != NULL) {
        printf("%d ", cur->data);
        cur = cur->next;
    }
    printf("\n");
}

int main() {
    List* list = (List*)malloc(sizeof(List));
    initList(list);

    insertAtHead(list, 1);
    insertAtTail(list, 5);
    insertAtIndex(list, 1, 3);
    printList(list);

    deleteAtHead(list);
    deleteAtIndex(list, 1);
    printList(list);

    free(list);
    return 0;
}

注意：在使用完毕后，需要手动释放双向链表和节点的内存空间，否则会造成内存泄漏。