用C语言写一个 字符双向循环链表，实现插入手动输入的字符

好的，这是一个技术问题，我可以回答。以下是用C语言实现字符双向循环链表的代码：

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

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

Node *create_node(char data) {
    Node *new_node = (Node *)malloc(sizeof(Node));
    new_node->data = data;
    new_node->prev = NULL;
    new_node->next = NULL;
    return new_node;
}

void insert_node(Node **head, char data) {
    Node *new_node = create_node(data);
    if (*head == NULL) {
        *head = new_node;
        (*head)->prev = *head;
        (*head)->next = *head;
    } else {
        new_node->prev = (*head)->prev;
        new_node->next = *head;
        (*head)->prev->next = new_node;
        (*head)->prev = new_node;
    }
}

void print_list(Node *head) {
    if (head == NULL) {
        printf("List is empty.\n");
        return;
    }
    Node *current = head;
    do {
        printf("%c ", current->data);
        current = current->next;
    } while (current != head);
    printf("\n");
}

int main() {
    Node *head = NULL;
    char input;
    printf("Please enter characters to insert into the list (enter '.' to stop):\n");
    do {
        scanf(" %c", &input);
        if (input != '.') {
            insert_node(&head, input);
        }
    } while (input != '.');
    printf("The list is:\n");
    print_list(head);
    return 0;
}

这个程序可以让用户手动输入字符，并将它们插入到双向循环链表中。最后，程序会输出整个链表中的字符。