队列 C++ 适用各种数据类型

#ifndef QUEUE_HH#define QUEUE_HH#include<iostream>#include<stdlib.h>using namespace std;template <typename type>struct Node{    type value;    Node *next;};template <typename type>class Queue{private:    int len;    Node<type> *head;    Node<type> *tail;public:    Queue();    ~Queue();    bool isEmpty();    type poll();    bool add(type);    int getLength();};template <typename type>Queue<type>::Queue(){    this->len = -1;    this->head = NULL;    this->tail = NULL;}template <typename type>bool Queue<type>::isEmpty(){    if(this->len == -1 || this->head == NULL)    {        return true;    }    return false;}//in queuetemplate <typename type>bool Queue<type>::add(type value){    Node<type> *vNode = new Node<type>();    vNode->value = value;    if(vNode == NULL)    {        return false;    }    if(this->len == -1 || this->head == NULL)    {        vNode->next = NULL;        this->head = vNode;        this->tail = vNode;    }    else    {        vNode->next = NULL;        this->tail->next = vNode;        this->tail = vNode;    }    this->len++;    return true;}//out of queuetemplate <typename type>type Queue<type>::poll(){    if(this->len == -1 || this->head == NULL)    {        return NULL;    }    type tValue = this->head->value;    Node<type> *tNode = this->head;    this->head = this->head->next;    free(tNode);    tNode = NULL;    this->len--;    return tValue;}//get queue lengthtemplate <typename type>int Queue<type>::getLength(){    return this->len + 1;}template <typename type>Queue<type>::~Queue(){    while(this->poll()) {}}#endif