双向链表代码实现

完整实现代码

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

//链表结点
typedef struct ListNode {
    int data;
    struct ListNode *next;
    struct ListNode *prev;
} ListNode;

//链表
typedef struct LinkList {
    int length;
    ListNode *head;
    ListNode *tail;
} LinkList;

//初始化
void initLinkList(LinkList *list) {
    list->length = 0;
    list->tail = list->head = NULL;
}

//创建结点
ListNode *createListNode(int data, ListNode *next, ListNode *prev) {
    ListNode *node = (ListNode *) malloc(sizeof(ListNode));
    node->data = data;
    node->next = next;
    node->prev = prev;
    return node;
}

//按位置获取结点
ListNode *getIndexLinkList(LinkList *list, int index) {
    if (index < 0 || index > list->length - 1) {
        printf("获取失败！\n");
        return NULL;
    }
    ListNode *p = list->head;
    for (int i = 0; i < index; ++i) {
        p = p->next;
    }
    return p;
}

//按值获取结点
ListNode *getDataLinkList(LinkList *list, int data) {
    ListNode *p = list->head;
    for (int i = 0; i < list->length; ++i) {
        if (p->data == data) {
            return p;
        }
        p = p->next;
    }
    printf("获取失败！\n");
    return NULL;
}

//头插法
void insertHeadLinkList(LinkList *list, int data) {
    list->head = createListNode(data, list->head, NULL);
    if (list->tail) {
        list->head->next->prev = list->head;
    } else {
        list->tail = list->head;
    }
    list->length++;
}

//尾插法
void insertTailLinkList(LinkList *list, int data) {
    list->tail = createListNode(data, NULL, list->tail);
    if (list->head) {
        list->tail->prev->next = list->tail;
    } else {
        list->head = list->tail;
    }
    list->length++;
}

//指定位置插入
void insertLinkList(LinkList *list, int data, int index) {
    if (index < 0 || index > list->length) {
        printf("插入失败！\n");
    } else if (index == 0) {
        insertHeadLinkList(list, data);
    } else if (index == list->length) {
        insertTailLinkList(list, data);
    } else {
        ListNode *p = getIndexLinkList(list, index);
        p = createListNode(data, p, p->prev);
        p->next->prev = p;
        p->prev->next = p;
        list->length++;
    }
}

//指定元素删除
void deleteDataLinkList(LinkList *list, int data) {
    ListNode *p = getDataLinkList(list, data);
    if (!p) {
        printf("删除失败！\n");
        return;
    } else if (!p->prev && !p->next) {
        list->head = list->tail = NULL;
    } else if (!p->prev) {
        list->head = list->head->next;
        list->head->prev = NULL;
    } else if (!p->next) {
        list->tail = list->tail->prev;
        list->tail->next = NULL;
    } else {
        p->next->prev = p->prev;
        p->prev->next = p->next;
    }
    free(p);
    list->length--;
}

//指定位置删除
void deleteIndexLinkList(LinkList *list, int index) {
    ListNode *p = getIndexLinkList(list, index);
    if (!p) {
        printf("删除失败！\n");
        return;
    } else if (!p->prev && !p->next) {
        list->head = list->tail = NULL;
    } else if (!p->prev) {
        list->head = list->head->next;
        list->head->prev = NULL;
    } else if (!p->next) {
        list->tail = list->tail->prev;
        list->tail->next = NULL;
    } else {
        p->next->prev = p->prev;
        p->prev->next = p->next;
    }
    free(p);
    list->length--;
}

//打印链表
void printLinkList(LinkList *list) {
    ListNode *node = list->head;
    while (node) {
        printf("%d ", node->data);
        node = node->next;
    }
    printf("\n");
}

//测试代码
void test() {
    LinkList list;
    initLinkList(&list);
    int sel, data, index;
    while (true) {
        printf("1.头插法插入\n2.尾插法插入\n3.指定位置插入\n4.指定元素删除\n5.指定位置删除\n6.打印链表\n");
        scanf("%d", &sel);
        switch (sel) {
            case 1: {
                printf("元素：");
                scanf("%d", &data);
                insertHeadLinkList(&list, data);
                break;
            }
            case 2: {
                printf("元素：");
                scanf("%d", &data);
                insertTailLinkList(&list, data);
                break;
            }
            case 3: {
                printf("元素：");
                scanf("%d", &data);
                printf("位置：");
                scanf("%d", &index);
                insertLinkList(&list, data, index);
                break;
            }
            case 4: {
                printf("元素：");
                scanf("%d", &data);
                deleteDataLinkList(&list, data);
                break;
            }
            case 5: {
                printf("位置：");
                scanf("%d", &index);
                deleteIndexLinkList(&list, index);
                break;
            }
            case 6: {
                printLinkList(&list);
                break;
            }
            default:
                return;
        }
        system("pause");
        system("cls");
    }
}

//主函数
int main() {
    test();
    return 0;
}