双向链表

双向链表

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


typedef struct node {
    int data;

    struct node *next;
    struct node *prev;
}node_t;

int main(void)
{
    node_t head = {.data = 0, .next = &head, .prev = &head};
    node_t *n;
    int num;

    while (1)
    {
        printf("input number: ");
        scanf("%d", &num);

        if (num < 0)
            break;
        
        n = malloc(sizeof(node_t));
        n->data = num;

        n->next = &head;
        n->prev = head.prev;

        head.prev->next = n; //这里是head.prev表示头节点的前一个节点(也就是尾节点)的next指针变量
        head.prev = n; //头节点的prev指针变量存放n节点地址
    }

    for (n = head.prev; n != &head; n = n->prev)
        printf("%d\n", n->data);

    return 0;
}