数据结构期末复习（三）--循环队列定义及使用

#include<iostream>
using namespace std;
#define Ok 1
#define Error 0
#define Overflow -1
#define Maxsize 100
typedef struct
{
    int *base;   //存储空间基地址
    int front;   //头指针，每次在队头删除元素，front加1
    int rear;    //尾指针，每次在队尾插入元素，rear 加1
    int queuesize;
} SqQueue;

//初始化
int Init_Queue(SqQueue &Q)
{
    //构造一个最大存储空间为MaxSize的空循环队列Q
    Q.base = new int[Maxsize];
    if(!Q.base)        //存储分配失败
        exit(Overflow);
    Q.queuesize = Maxsize;
    Q.front = Q.rear = 0;  //头尾指针置为0，对列为空
    return Ok;
}

//求队列长
int QueueLength(SqQueue Q)
{
    return (Q.rear - Q.front + Maxsize) % Maxsize;
}

//入队
int EnQueue(SqQueue &Q, int e)
{
    if((Q.rear + 1) % Q.queuesize == Q.front)
        return Error; //队满
    Q.base[Q.rear] = e; //保存队头元素
    Q.rear = (Q.rear + 1) % Q.queuesize; //队头指针加1
    return Ok;
}

//出对
int DeQueue(SqQueue &Q)
{
    if(Q.front == Q.rear)  //队空
        return Error;
    Q.front = (Q.front + 1) % Q.queuesize;
    return Ok;
}

//取队头元素
int GetHead(SqQueue Q)
{
    if (Q.front != Q.rear)  //队非空
    {
        return Q.base[Q.front]; //返回队头元素的值，队头指针不变
    }
}

//输出
void printqueue(SqQueue Q)
{
    while(Q.front != Q.rear)
    {
        cout << GetHead(Q) << " ";
        Q.front = (Q.front + 1) % Q.queuesize;
        //DeQueue(Q);
    }
    cout << endl;
}
int main()
{
    SqQueue q;
    Init_Queue(q);
    cout << "请输入数字:(0-3):0--退出，1--求表长，2--DeQue，3--EnQue\n";
    for (int i = 0; i < 10; ++i)
        EnQueue(q, i);
    int c, d;
    for(int i = 0; i < 4; ++i)
    {
        cin >> c;
        if(c == 1)
            cout << QueueLength(q) << endl;
        else if(c == 2)
        {
            cout << "yuan:";
            printqueue(q);
            DeQueue(q);
            cout << "DE hou:";
            printqueue(q);
            cout << "Len=: " << QueueLength(q) << endl;
        }
        else if(c == 3)
        {
            cout << "yuan:";
            printqueue(q);
            cout << "input num:";
            cin >> d;
            EnQueue(q, d);
            cout << "En hou:";
            printqueue(q);
            cout << "Len=: " << QueueLength(q) << endl;
        }
        else if(c == 0)
        {
            return 0;
        }
    }
    return 0;
}