这里对单链表的循环模式写了一些代码，只是单纯从原理上做出了说明，并没有加入相关的容错
单链表亦即ring buffer
单链表的循环模式和非循环的单链表有什么很大的区别，只是在初始时要把head->next = NULL 变成 head->next = head即可，另外在判断链表结束时的条件也要相应的从p->next == NULL 改成 p->next = head.
下面是代码
// // main.c // cicular_linked_list // // Created by zhong on 25.05.19. // Copyright © 2019 zhong. All rights reserved. // #include <stdio.h> #include <stdlib.h> typedef struct ListNode { int data; struct ListNode *next; } node_t; node_t *init() { node_t *head = malloc(sizeof(node_t)); head->data = 0; head->next = head; return head; } int insert_head(node_t *head, int data) { node_t *newnode = malloc(sizeof(node_t)); newnode->data = data; newnode->next = head->next; head->next = newnode; return 0; } int insert_index(node_t *head, int data, int index) { node_t *newnode = malloc(sizeof(node_t)); newnode->data = data; while(index--) { head = head->next; } newnode->next = head->next; head->next = newnode; return 0; } int delete_head(node_t *head) { node_t *tmp; tmp = head->next; head->next = head->next->next; free(tmp); return 0; } int delete_index(node_t *head, int index) { node_t *tmp; while(index--) { head = head->next; } tmp = head->next; head->next = head->next->next; free(tmp); return 0; } int change(node_t *head, int data, int index) { while(index--) { head = head->next; } head->next->data = data; return 0; } int search(node_t *head, int data) { node_t *p; int index = -1; p = head; while(p->next != head) { p = p->next; index++; if(data == p->data) { return index; } } printf("no data was found\n"); return -1; } int destroy(node_t *head) { node_t *p; p = head; while(p->next != head) { delete_head(p); p = p->next; } free(head); return 0; } int print_list(node_t *head) { node_t *p; p = head; while(p->next != head) { p = p->next; printf("%d ", p->data); } printf("\n"); return 0; } int main(int argc, const char * argv[]) { node_t *list; int pos; list = init(); for(int i=0; i<10; i++) { insert_head(list, i); } print_list(list); insert_index(list, 20, 1); print_list(list); delete_head(list); print_list(list); delete_index(list, 1); print_list(list); change(list, 80, 0); print_list(list); pos = search(list, 20); printf("the position is %d\n", pos); destroy(list); return 0; }