以带头节点的单向循环链表表示队列

假设以带头节点的单项循环链表表示队列，并且只设一个指针指向队尾元素节点（注意：不设头指针），试设计并验证相应的队列初始化，对列的判空，入队列，出队列和遍历队列的算法。

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

#define OK 1
#define ERROR 0
typedef struct circle_list
{
	int data;
	struct circle_list *next;
}list;

list *create(list *rear)
{
	int m,i=1;
	list *p,*q,*head;
	rear=(list *)malloc(sizeof(list));
	head=(list *)malloc(sizeof(list));
	rear->next=head;
	head->next=rear;
	p=q=head;
	printf("共需要输入几项:");
	scanf("%d",&m);
	srand((unsigned)time(NULL)); 
	while(i<=m)
	{
		p=(list *)malloc(sizeof(list));
		printf("第%d项:",i);
		p->data=rand()%100+1;
		printf("%d\n",p->data);
		p->next=q->next;
		q->next=p;
		q=p;
		i++;
	}
	q->next=rear;
	return rear;
}
void output(list *rear)
{
	list *p;
	p=rear->next->next;
	while(p!=rear)
	{	printf("%-5d",p->data);
		p=p->next;
	}	
	printf("\n----------------------------\n\n");
}
int Del_pos(list *rear,int pos)
{
	int i=1;
	list *p,*q;
	p=rear->next->next;
	q=rear->next;
	if(pos==1)
	{
		q->next=p->next;
		free(p);
		return OK;
	}
	while(p!=rear&&i<pos-1)
	{
		i++;
		p=p->next;
	}
	q=p->next;
	p->next=q->next;
	free(q);

	return OK;
}

void destroylist(list *rear)
{
	list *p=rear->next;
	while(p!=rear)
	{
		p=rear->next;
		rear->next=rear->next->next;
		free(p);
	}
}
void main()
{
	list *l=NULL;
	l=create(l);
	output(l);
	Del_pos(l,1);
	output(l);
	destroylist(l);
}