带头节点循环链表实现队列

队列的特征就是“先入先出”，入队时在链表的尾部插入数据，出队时删除掉头节点后面的节点，需要一个尾指针，始终指向链表的尾部（新加进来的节点）。具体请看原理图：
在这里插入图片描述
代码实现

#include <stdio.h>
#include <stdlib.h>typedef struct List
{int data;			//数据域struct List *next;	//指针域
}ListNode;				//节点信息ListNode *rear;			//尾指针void Init(ListNode *head);				//队列初始化
void push(ListNode *head, int data);	//入队
void pop(ListNode *head);				//出队
void print(ListNode *head);				//显示队内元素int main()
{ListNode head;Init(&head);push(&head, 1);print(&head);pop(&head);print(&head);pop(&head);print(&head);system("pause");return 0;
}void Init(ListNode *head)
{head->data = 0;head->next = head;rear = head;		//尾指针指向头节点
}void push(ListNode *head,int data)
{ListNode *tem = (ListNode *)malloc(sizeof(ListNode));if (tem == NULL){printf("创建新节点失败，入队失败");return;}rear->next = tem;		//尾指针指向的节点的指针指向新节点tem->data = data;tem->next = head;		//尾结点指向头，实现循环rear = tem;				//尾指针后移
}void pop(ListNode *head)
{if (head ->next == head){printf("队内无元素，出队错误\n");return;}ListNode *tem = head->next;head->next = tem->next;		//头节点指向下下个节点printf("出队元素: %d\n", tem->data);if (tem->next == head){rear = head;			//删除到最后一个元素时，尾指针指向头节点}free(tem);tem=NULL;
}void print(ListNode *head)
{ListNode *tem = head->next;if (tem == head){printf("当前队列无元素\n");return;}for (; tem != head; tem = tem->next){printf("%d  ", tem->data);}printf("\n");
}