请以C语言实现双向链表的清空

好的，以下是以C语言实现双向链表的清空的代码：

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

typedef struct node {
    int data;
    struct node* next;
    struct node* prev;
} Node;

Node* head = NULL;

void insert(int value) {
    Node* newNode = (Node*)malloc(sizeof(Node));
    newNode->data = value;
    newNode->prev = NULL;
    newNode->next = head;

    if (head != NULL) {
        head->prev = newNode;
    }

    head = newNode;
}

void clear() {
    Node* current = head;
    Node* next;

    while (current != NULL) {
        next = current->next;
        free(current);
        current = next;
    }

    head = NULL;
}

int main() {
    insert(10);
    insert(20);
    insert(30);

    printf("Before clear: ");

    Node* current = head;

    while (current != NULL) {
        printf("%d ", current->data);
        current = current->next;
    }

    clear();

    printf("\nAfter clear: ");

    current = head;

    while (current != NULL) {
        printf("%d ", current->data);
        current = current->next;
    }

    return 0;
}

这个代码实现了双向链表的插入，然后通过 clear() 函数将链表清空。在这个函数中，我们使用 while 循环遍历链表并释放所有节点，并将头节点设置为 NULL 表示链表为空。

注意，此处清空链表的方式并不是直接将头指针置为 NULL，而是通过循环遍历释放每个节点的方式清除整个链表。这样做是为了避免内存泄漏。