循环队列模版（链表实现）

用链表实现循环队列，也是写几个常用功能，其实和循环列表大同小异 ，就是它的一个特殊形式而已。

文件"myqueue.h"

#include<iostream>
using namespace std;

template<class T>
class My_queue;

template<class T>
class Node
{
private:
	T data;
	Node<T> *next;
public:
	Node()
	{
		next=0;
	}
	Node(T d)
	{
		data=d;
		next=0;
	}
	friend My_queue<T>;
};

template<class T>
class My_queue
{
private:
	Node<T> *tail;
public:
	My_queue()
	{
		tail=new Node<T>();
		tail->next=tail;
	}

	~My_queue()
	{
		clean();
		delete tail;
	}

	bool empty()
	{
		return (tail->next==tail);
	}

	int size()
	{
		int length=0;
		Node<T> *p=tail->next;
		p=p->next;
		while(p!=tail->next)
		{
			length++;
			p=p->next;
		}
		return length;
	}

	void push(T d)
	{
		Node<T> *p=new Node<T>(d);
		p->next=tail->next;
		tail->next=p;
		tail=p;
	}

	T front()
	{
		if(empty())
		{
			cout<<"queue is empty!"<<endl;
			exit(0);
		}
		Node<T> *p=tail->next;
		T data=p->next->data;
		return data;
	}

	T back()
	{
		if(empty())
		{
			cout<<"queue is empty!"<<endl;
			exit(0);
		}
		T data=tail->data;
		return data;
	}

	void pop()
	{
		Node<T> *r=tail->next;
		Node<T> *q=r->next;
		r->next=q->next;
		if(q==tail)
			tail=r;
		delete q;
	}

	void clean()
	{
		Node<T> *p=tail->next;
		Node<T> *q=p->next;
		while(q!=p)
		{
			p->next=q->next;
			delete q;
			p->next=q;
		}
		cout<<"clean is finished!"<<endl;
	}
};

测试代码"main.cpp"

#include"myqueue.h"

int main()
{
	My_queue<char> q;
	if(q.empty())
		cout<<"queue is empty"<<endl;

	q.push('I');
	q.push('L');
	q.push('O');
	q.push('V');
	q.push('E');
	q.push('U');

	cout<<"Now the queue's size is: "<<q.size()<<endl;

	cout<<"queue's back() is "<<q.back()<<'\n';
	cout<<"queue's front() is "<<q.front()<<endl;

	while(!q.empty())
	{
		cout<<q.front()<<" ";
		q.pop();
	}
	cout<<endl;
	return 0;
}