数据结构-编程实现队列的入队、出队、测长、打印、出队

1：代码如下：

#include "stdafx.h"
#include<malloc.h>
#include <iostream>
#include <assert.h>
using namespace std;
typedef struct _Node
{
    int data;
    struct _Node *next;//指向链表下一个指针
}node;

typedef struct _Queue
{
    node *front;//队头
    node *rear;//队尾
}MyQueue;

//构造空的队列
MyQueue *CreateMyQueue()//空队列给个地址，队首队尾置空
{
    MyQueue *q = (MyQueue *)malloc(sizeof(MyQueue));
    q->front = NULL;//把队首指针置空
    q->rear = NULL;//把队尾指针置空
    return q;
}

//入队，从队尾一端插入节点
MyQueue *enqueue(MyQueue *q, int data)
{
    node *newP = NULL;
    newP = (node *)malloc(sizeof(node));//新建节点
    newP->data = data;//复制节点数据
    newP->next = NULL;
    if (q->rear == NULL)//若队列为空，则新节点即使队首又是队尾，队尾为空，肯定为空
    {
        q->front = q->rear = newP;
    }
    else//若队列不为空，则新节点放到队尾，队尾指针指向新节点
    {
        q->rear->next = newP;//新节点放到队尾
        q->rear = newP;//将新节点作为新的队尾
    }
    return q;
}

/*队列的打印*/
void PrintMyQueue(MyQueue *q)
{
    node *pnode = q->front;
    if (pnode == NULL)//队列为空，空队列的队首队尾皆为空
    {
        printf("Empty Queue!
");
        return;
    }
    printf("data:");
    while (pnode != q->rear)//遍历队列
    {
        printf("%d", pnode->data);//打印节点数据
        pnode = pnode->next;
    }
    printf("%d", pnode->data);//打印队尾节点数据
}

//队列的测长
int GetLength(MyQueue *q)
{
    int nlen = 0;
    node *pnode = q->front;//指向对头
    if (pnode != NULL)//队列不为空
    {
        nlen = 1;
    }
    while (pnode != q->rear)//遍历队列
    {
        pnode = pnode->next;
        nlen++;
    }
    return nlen;
}

//出队，从队头一端删除节点
MyQueue *dequeue(MyQueue *q)
{
    node *pnode = NULL;
    pnode = q->front;//指向队头
    if (pnode == NULL)//队列为空
    {
        printf("Empty queue!
");
    }
    else
    {
        q->front = q->front->next;//新对头
        if (q->front == NULL)//当删除后队列为空时，对rear置空
        {
            q->rear = NULL;
        }
        free(pnode);
    }
    return q;
}

int main()
{
    int nlen = 10;
    MyQueue *hp = CreateMyQueue();//建立队列
    enqueue(hp, 1);//入队1 2 3 4
    enqueue(hp, 2);
    enqueue(hp, 3);
    enqueue(hp, 4);
    nlen = GetLength(hp);//获得队列的长度
    printf("nlen=%d
", nlen);
    PrintMyQueue(hp);
    dequeue(hp);
    cout << "出队后：" << endl;
    PrintMyQueue(hp);
    return 0;
}

运行结果：