//顺序循环队列
#include<iostream>
using namespace std;
typedef int elemType;
const int MAXSIZE = 20;

struct Queue
{
    elemType data[MAXSIZE];
    int front;//头指针
    int rear;//尾指针，若队列不空，指向队列队尾元素的下一个位置
};

//初始化
void InitQueue(Queue *q)
{
    q->front = q->rear = 0;
}

//求队列元素数
int LengthQueue(Queue *q)
{
    return (q->rear - q->front + MAXSIZE)%MAXSIZE;
}

//若队列未满，插入元素e为队列新的队尾元素
void EnQueue(Queue *q, elemType e)
{
    if((q->rear+1)%MAXSIZE == q->front)
        cout<<"出错，队列已满."<<endl;
    q->data[q->rear] = e;
    q->rear = (q->rear +1)%MAXSIZE;
}

//若队列不空，删除队头元素
void DeQueue(Queue *q, elemType *e)
{
    if(q->front == q->rear)
        cout<<"出错，队列为空."<<endl;
    *e = q->data[q->front];
    q->front = (q->front+1)%MAXSIZE;
}

//遍历队列
void TraQueue(Queue *q)
{
    if(q->front == q->rear)
        cout<<"队列为空."<<endl;
    int num = 1;
    for(int i=(q->front)%MAXSIZE;i<q->rear;i=(i+1)%MAXSIZE)
    {
        cout <<num<<":\t"<<q->data[i]<<endl;
    }
}

int main()
{
    Queue q;
    InitQueue(&q);
    for(int i=1;i<7;i++)
        EnQueue(&q,i);
    int length = LengthQueue(&q);
    cout <<"队列长度为： "<< length <<endl;
    TraQueue(&q);
    cout<<endl;

    cout<<"删除队头元素后，队列为："<<endl;
    elemType x = 0;
    DeQueue(&q,&x);
    TraQueue(&q);
    cout<<endl;

    for(int i=0;i<5;i++)
        DeQueue(&q,&x);
    TraQueue(&q);
    cout<<endl;

    return 0;
}