循环链表操作(链表带头节点)

#ifndef CIRCULARLIST_H
#define CIRCULARLIST_H

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

typedef int ElemType;

// 循环链表节点
typedef struct CircularNode{
    ElemType data;
    struct CircularNode *next;
}*CircularList;

// 返回一个动态分配的新节点,该节点尾部指向头部(头结点不用于存放数据)
CircularList NewCircularListNode()
{
    CircularList list = (CircularList)malloc(sizeof(struct CircularNode));
    if (!list)
        return NULL;
    memset(list, 0, sizeof(struct CircularNode));
    list->next = list;
    return list;
}


void CircularListInfo(CircularList list)
{
    CircularList pos = list;   // 头结点
    // 先遍历元素,再打印其值
    printf("listhead=%p: ",list);

    if (list->next == list)  {  // 只有头结点,没有有效数据
        printf("list is null\n");
        return;
    }
    pos = pos->next;    // 第一个节点开始
    while(pos != list){
        printf("%d, ",pos->data);
        pos = pos->next;
    }
    printf("\n");
}

// 在第i个节点前