队列循环实现（C++）

C++队列的循环实现：

const int MAXQUEUE = 10;

template<class T>
class ZtkQueue {
public:
    ZtkQueue();
    bool empty() const;
    ErrorCode append(const T &x);
    ErrorCode serve();
    ErrorCode retrieve (T &x)const;
    bool full() const;
    int size() const;
    void clear();
    ErrorCode serve_and_retrieve(T &x);
private:
    int count;
    int rear;
    int front;
    T entry[MAXQUEUE];
};

template<class T>
ZtkQueue<T>::ZtkQueue():count(0),front(0),rear(MAXQUEUE-1)
{
}

template<class T>
ErrorCode ZtkQueue<T>::serve_and_retrieve(T &x)
{
    ErrorCode outcome = success;
    if(count > 0)
    {
        count--;
        x=entry[front];
        front = ((front+1)==MAXQUEUE)?0:front+1;
    }
    else
        outcome = underflow;
    return outcome;
}

template<class T>
void ZtkQueue<T>::clear()
{
    count=0;
    rear=MAXQUEUE - 1;
    front=0;
}

template<class T>
int ZtkQueue<T>::size() const
{
    return count;
}

template<class T>
bool ZtkQueue<T>::full() const
{
    if(count == MAXQUEUE)
        return true;
    else
        return false;
}

template<class T>
ErrorCode ZtkQueue<T>::retrieve(T &x) const
{
    ErrorCode outcome = success;
    if(!empty())
        x = entry[front];
    else
        outcome = underflow;
    return outcome;
}

template<class T>
ErrorCode ZtkQueue<T>::serve()
{
    ErrorCode outcome = success;
    if(count>0)
    {
        count--;
        front = ((front+1)==MAXQUEUE)?0:front+1;
    }
    else
        outcome = underflow;
    return outcome;
}

template<class T>
bool ZtkQueue<T>::empty()const
{
    if(count>0)
        return false;
    else
        return true;
}

template<class T>
ErrorCode ZtkQueue<T>::append(const T &x)
{
    ErrorCode outcome = success;
    if(count < MAXQUEUE)
    {
        count++;
        rear = ((rear+1)==MAXQUEUE)?0:rear+1;
        entry[rear]=x;
    }
    else
        outcome = overflow;
    return outcome;
}