// queue.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"
#include<stdio.h>
#include<ctype.h>
#include<string.h>
#include<malloc.h>

//定义链队节点类型
typedef struct LinkQueueNode
{
 int data;
 struct LinkQueueNode * next;
}LinkQueueNode;

//定义链队类型
typedef struct LinkQueue
{
 LinkQueueNode *front,*rear;
}LinkQueue;

//初始化队列
void InitQueue(LinkQueue *lq)
{
 LinkQueueNode *p;
 p=(LinkQueueNode *)malloc(sizeof(LinkQueueNode));
 lq->front=p;
 lq->rear=p;
 (lq->front)->next=NULL;
}

//入队,入队节点值为x
void EnterQueue(LinkQueue * lq,int x)
{
 LinkQueueNode *p;
 p=(LinkQueueNode *)malloc(sizeof(LinkQueueNode));
 p->data=x;
 p->next=NULL;
 (lq->rear)->next=p;
 lq->rear=p;
}

//出队，出队节点值为x
OutQueue(LinkQueue *lq,int *x)
{
 LinkQueueNode *s;
 if(lq->front==lq->rear)
 {
  printf("队空");
  return 0;
 }
 else
 {
  s=(lq->front)->next;
  *x=s->data;
  (lq->front)->next=s->next;
  if(s->next==NULL)
   lq->rear=lq->front;
  free(s);
  return 1;
 }
}

//判断队列是否为空
EmptyQueue(LinkQueue lq)
{
 if(lq.rear==lq.front)
  return 1;
 else
  return 0;
}

//取队列头节点，队头节点值为x
GetHead(LinkQueue lq,int *x)
{
 LinkQueueNode *p;
 if(lq.rear==lq.front)
  return 0;
 else
 {
  p=lq.front->next;
  *x=p->data;
  return 1;
 }
}

void main()
{
 LinkQueue lq;
 int n;
 char ch;
 InitQueue(&lq);
 while(1)
 {
  printf("\n请输入命令 A 入队； O 出队  L 显示队列内容：\n");
  scanf("%c",&ch);

  switch(toupper(ch))
  {
  case 'A':
   printf("请输入节点值，节点准备入队\n");
   scanf("%d",&n);
   EnterQueue(&lq,n);
   break;
  case 'O':
   if(!EmptyQueue(lq))
   {
    OutQueue(&lq,&n);
    printf("值为%d的节点出队",n);
   }
   else
    printf("队列为空\n");
   break;
  case 'L':
   printf("下列节点依次出队\n");
   break;
  }
  if(toupper(ch)=='L')
  {
   while(!EmptyQueue(lq))
   {
    OutQueue(&lq,&n);
    printf("值为%d的节点出队\n",n);
   }
   break;
  }
 }
}