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  C++ Prime确实有点难啊！看了好久都没弄清楚，一点点慢慢来。

#include <iostream>

#include <string>

#include <cstdio>

template <class Type> class Queue;

//function template declaration must precede friend declaration in QueueItem

template <class T>

std::ostream& operator<<(std::ostream&,const Queue<T>&);

template <class Type> class QueueItem{

     friend class Queue<Type>;

	 // needs access to item and next

	 friend std::ostream&

		 operator<< <Type> (std::ostream&,const Queue<Type>&);

	 // private class: no public section

	 QueueItem(const Type &t):item(t),next(0){}

	 Type item;                   // value stored in this element

	 QueueItem *next;             // pointer to next element in the Queue

};

template <class Type> class Queue{

	// needs access to head

	friend std::ostream&

	operator << <Type> (std::ostream&,const Queue<Type>&);

public:

	// empty Queue

	Queue():head(0),tail(0){}

	// construct a Queue from a  pair of iterators on some sequence

	template <class It>

	Queue(It beg,It end):

	    head(0),tail(0){ copy_elems(beg,end); }

	// copy control to manage pointers to QueueItems in the Queue

	Queue(const Queue &Q)

		:head(0),tail(0){ copy_elems(Q); }

	Queue& operator=(const Queue&);            // left as exercise for the reader

	~Queue() { destroy(); }

	// replace current Queue by contents delimited by a pair of iterators

	template <class Iter> void assign(Iter,Iter);

	// return element from head of Queue

	// unchecked operation:front on an empty Queue is undefined

	Type& front() {return head->item; }

	const Type &front() const {return head->item;}

	void push(const Type &);

	void pop();

	bool empty()const{           //true if no elements in the Queue

	    return head == 0;

	}

private:

	QueueItem<Type> *head;

	QueueItem<Type> *tail;

	void destroy();

	void copy_elems(const Queue&);

	// version of copyto be used by assign to copy elements from iterator range

	template <class Iter> void copy_elems(Iter,Iter);

};

// push 函数

// push 成员将新项放在队列末尾

template <class Type> void Queue<Type>::push(const Type &val)

{

	// allocate a new QueueItem object

	QueueItem<Type> *pt = new QueueItem<Type>(val);

	// put item onto existing(眼下) queue

	if(empty())

		head = tail = pt;    // the queue now has only one element

	else {

		tail->next = pt;     // add new element to end of the queue

		tail = pt;

	}

}

//copy_element 函数

template <class Type>

void Queue<Type>::copy_elems(const Queue &orig)

{

	// copy elements from orig into this Queue

	// loop stops when to pt == 0, which happens when we reach orig.tail

	for (QueueItem<Type> *pt = orig.head; pt; pt = pt->next)

		push(pt->item);              // copy element

}

// destroy 函数

template <class Type> void Queue<Type>::destroy()

{

	while (!empty())

		pop();

}

//pop函数

template <class Type> void Queue<Type>::pop()

{

	// pop is unchecked: Popping off an empty Queue is undefined

	QueueItem<Type>* p = head;

	head = head->next;

	delete p;

}

int main()

{

	int n,val;

	Queue<int> IntQ;

	/*Queue<double> DouQ;

	Queue<string> StrQ;*/

	printf("Please enter you want total number: ");

	std::cin>>n;

	while(n){

	     std::cin>>val;

		 IntQ.push(val);

		 n--;

	}

	while(!IntQ.empty()){

		std::cout<<IntQ.front()<<std::endl;

		IntQ.pop();

	}

	return 0;

}