链队列的初始化

#include <iostream>
using namespace std;
template <class T>
struct Node
{
    T data;
    Node *next;
    Node():next(NULL){}
    Node(T _data):data(_data),next(NULL){}
};
template <class T>
class Queue
{
private:
    Node<T> *front_,*rear;
public:
    Queue():front_(NULL),rear(NULL){}
    bool EnQueue(const T &x);
    bool DeQueue(T &x);
    T getFront();
    T getRear();
    int getSize();
    bool IsEmpty();

};

template <class T>
bool Queue<T>::EnQueue(const T &x)
{
   if(front_==NULL)
   {
       rear=front_=new Node<T>(x);
       return true;

   }
   else{
    rear->next=new Node<T>(x);
    if(rear->next==NULL) return false;
    rear=rear->next;

   }
   return true;
}

template <class T>
bool Queue<T>::DeQueue(T &x)
{
    if(IsEmpty()) return false;
    else
    {
       Node<T> *p=front_;
       x=front_->data;
       front_=front_->next;
       delete p;
       return true;
    }
}

template <class T>
T Queue<T>::getFront()
{
   return front_->data;
}
template <class T>
T Queue<T>::getRear()
{
    return rear->data;
}
template <class T>
int Queue<T>::getSize()
{
    if(front_==NULL) return 0;
    if(front_==rear&&front_!=NULL) return 1;
    int n=2;
    Node<T> *current=front_;
    while(current->next!=rear)
    {
        n++;
        current=current->next;
    }
    return n;
}
template <class T>
bool Queue<T>::IsEmpty()
{
    if(front_==NULL)
        return true;
    return false;
}
int main()
{
    Queue<char> q;
    char ch;
    q.EnQueue('a');

    q.DeQueue(ch);
    cout<<"ch="<<ch<<endl;
    q.EnQueue('b');
    q.EnQueue('c');
    cout<<"size="<<q.getSize()<<endl;
    cout<<"rear="<<q.getRear()<<endl;
    q.DeQueue(ch);
    cout<<"ch="<<ch<<endl;
    return 0;
}