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前言

编程实现循环队列的以下基本操作：建队列，取队头元素，入队，出队。
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下面就让我们一起来看看怎么实现吧

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一、代码实现

#include <iostream>

using namespace std;

#define ERROR -1
#define OK 1

typedef int QElemType;
typedef int Status;

//循环队列的存储结构
#define MAXQSIZE 100 //最大队列长度
typedef  struct
{
    
    QElemType *base;       //用于动态分配存储空间
    int  front;            //队头索引
    int  rear;             //队尾索引
} SqQueue;

//初始化
void InitQueue (SqQueue &Q)
{
    
    //构造一个空队列
    Q.base =new QElemType[MAXQSIZE];
    Q.front=Q.rear=0;
}

//销毁队列
void DestroyQueue(SqQueue &Q)
{
    
    if(Q.base)
        free(Q.base);
    Q.base = NULL;
    Q.front = Q.rear = 0;
}

//清空队列
void ClearQueue(SqQueue &Q)
{
    
    Q.front=Q.rear=0;
}
//求长度
int  QueueLength (SqQueue Q)
{
    
    return (Q.rear-Q.front+MAXQSIZE)%MAXQSIZE;
}

//判空
bool QueueEmpty (SqQueue Q)
{
    
    return (Q.front==Q.rear);
}

//求队头元素
Status GetHead (SqQueue Q, QElemType &e)
{
    
    if(Q.front==Q.rear) return ERROR;
    e=Q.base[Q.front];
    return OK;
}

//循环队列入队
Status EnQueue(SqQueue &Q,QElemType e)
{
    
    if((Q.rear+1)%MAXQSIZE==Q.front)  return ERROR;
    Q.base[Q.rear]=e;
    Q.rear = (Q.rear+1) % MAXQSIZE;
    return OK;
}

//循环队列出队
Status DeQueue (SqQueue &Q,QElemType &e)
{
    
    if(Q.front==Q.rear) return ERROR;
    e=Q.base[Q.front];
    Q.front=(Q.front+1) % MAXQSIZE;
    return OK;
}

//遍历使队列显示
void DisplayQueue(SqQueue Q)
{
    
    int i=Q.front;
    while(Q.front!=Q.rear && (i+MAXQSIZE) % MAXQSIZE != Q.rear)
    {
    
        cout<<Q.base[i]<<endl;
        i++;
    }
}
void show_help()
{
    
    cout<<"******* Data Structure ******"<<endl;
    cout<<"1----清空循环队列"<<endl;
    cout<<"2----判断循环队列是否为空"<<endl;
    cout<<"3----求循环队列长度"<<endl;
    cout<<"4----取队头元素"<<endl;
    cout<<"5----入队"<<endl;
    cout<<"6----出队"<<endl;
    cout<<"7----显示队列"<<endl;
    cout<<" 退出，输入0"<<endl;

}
int main()
{
    
    char operate_code;
    show_help();
    SqQueue Q;
    InitQueue(Q);
    QElemType e;
    int i;
    while(1)
    {
    
        cout<<"请输入操作代码:";
        cin>>operate_code;
        if(operate_code=='1')
        {
    
            cout<<"The queue has been cleared."<<endl;
            ClearQueue(Q);

        }
        else if (operate_code=='2')
        {
    
            if(QueueEmpty(Q))
                cout<<"The queue is empty."<<endl;
            else
                cout<<"The queue is not empty."<<endl;

        }
        else if (operate_code=='3')
        {
    
            cout<<"The length of queue is:"<<QueueLength(Q)<<endl;

        }
        else if (operate_code=='4')
        {
    
            cout<<"队头元素为："<<endl;
            if(GetHead(Q,e) == 1) cout<<e<<endl;
            else cout <<"error"<<endl;
        }
        else if (operate_code=='5')
        {
    
            cout<<"请输入你想要入队的数："<<endl;
            cin>>e;
            EnQueue(Q,e);
        }
        else if (operate_code=='6')
        {
    
            cout<<"出队元素为："<<endl;
            if(DeQueue(Q,e)) cout<<e<<endl;
        }
        else if (operate_code=='7')
        {
    
            cout<<"The contents of the queue are:"<<endl;
            DisplayQueue(Q);
        }
        else if (operate_code=='0')
        {
    
            break;
        }
        else
        {
    
            cout<<"\n操作码错误！！！"<<endl;
            show_help();
        }
    }
    //调用销毁栈函数
    DestroyQueue(Q);
    return 0;
}

二、运行结果

总结

本文用来介绍数据结构中循环队列的代码实现过程及运行结果示例。用菜单样式显示循环队列的初始化、清空、销毁、求长度、求队头元素、判空、入队、出队以及遍历队列使其显示等操作。