队列循环实现（C++）

C++队列的循环实现：

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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;

}