【数据结构】队列的出队和入队操作

队列的操作规则是先进先出，要注意一下，

1.队列为空

2.队列只有一个元素，即头尾指针都指向空 

3.初始化队列时，分配空间后不要忘记将头为指针置空

// 13_4.cpp : Defines the entry point for the console application.
//
 
#include "stdafx.h"
#include <string.h>
#include <conio.h>
#include <stdio.h>
#include <iostream>
using namespace std;
 
typedef struct student
{
	int data;
	struct student *next;
}node;
 
typedef struct linkqueue
{
	node *first, *rear;
}queue;
 
queue *insert(queue *HQ, int x)
{
	node *p = (node *)malloc(sizeof(node));
	p->data = x;
	p->next = NULL;
	if (NULL == HQ->rear)
	{
		HQ->first = p;
		HQ->rear = p;
	}
	else
	{
		HQ->rear->next = p;
		HQ->rear = p;
	}
	cout << HQ->rear->data << endl;
	return HQ;
}
 
queue *del(queue *HQ)
{
	node *p;
	int x;
	if (NULL == HQ)
	{
		cout << "Queue is null!" << endl;
	}
	else
	{
		p