带头结点的循环链表表示队列 只设一个队尾指针，写置空，判队空，入队，出队，初始化队

#include <stdio.h>
#include<stdio.h>
#include<malloc.h>

typedef struct node{
        int data;
    struct node *next;
}Linklist;

typedef struct{
    Linklist *rear;
}LinkQ;

LinkQ *SetQueue(){
    LinkQ *Q;
    Q=(LinkQ *)malloc(sizeof(LinkQ));
    Q->rear->next=Q->rear;
    return Q;
}

int EmptyQueue(LinkQ *Q){
    if(!Q->rear)
        return 1;
    else
        return 0;
}

LinkQ *Add(LinkQ *Q,int x){
    LinkQ *p;
    p=(LinkQ *)malloc(sizeof(LinkQ));
    p->rear->data=x;
    p->next=Q->rear->next;
    Q->rear->next=p;
    Q->rear=p;
    return Q;
}

LinkQ *Delete(LinkQ *Q){
    LinkQ *p;
    if(!EmptyQueue){
        p=Q->rear->next;
        Q->rear->next=p->next;
        free(p);
    }
    return Q;
}

LinkQ InitQueue(LinkQ *Q){
    Q->rear=Q->rear->next;
    return Q;
}

void main(){
    int n,choice;
    LinkQ *S;
    do{
    printf("1.建空队\n");
    printf("2.判空队\n");
    printf("3.入队\n");
    printf("4.出队\n");
    printf("5.置空队\n");
    printf("6.退出\n");
    printf("请选择:");
    scanf("%d",&choice);
    switch(choice){
    case 1:SetQueue(); break;
    case 2:EmptyQueue(S);break;
    case 3:printf("输入元素,以-1结束:");
        scanf("%d",&n);
        while(n!=-1){
        Add(S,n);
        scanf("%d",&n);
        };break;
    case 4:Delete(S);break;
    case 5:InitQueue(S);break;
    }
    }while(choice!=6);
}