简单循环队列（C++模版技术实现）

下面代码仅供本人复习数据结构所用，实用性N低，各位飘过吧~~哈哈:>

// 
// C++ 模版技术实现简单循环队列示例. 
// 
 
#include <cstdlib>
#include <iostream>
#include <iomanip>
#include <stdexcept> 
 
//
// 循环队列类模版. 
// 
// 由于循环队列队尾永远为空，队列物理空间应比指定队列逻辑空间大 1，
// 而返回的队列大小 size 应该为逻辑大小. 
// 
// 入队/出队时当发生上/下溢将抛出异常. 
//
template <typename T>
class CircularQueue
{
private:
    T *_pQueue;
    size_t _front, _rear, _size;
    static const size_t _MAX_QUEUE_SIZE = 20;
 
public:
    CircularQueue(const size_t size = _MAX_QUEUE_SIZE)
        : _front(0)
        , _rear(0)
        , _size(size + 1)
    { _pQueue = new T[_size]; }
     
     
    ~CircularQueue(void)
    { delete[] _pQueue; }
     
     
    size_t getSize(void) const
    { return _size - 1; }
     
     
    T getFront(void) const
    { 
        if (isEmpty()) {
            throw std::underflow_error("队列为空 !"); 
        }
        return _pQueue[_front]; 
    }
     
     
    bool isEmpty(void) const
    { return _front == _rear; }
     
     
    bool isFull(void) const
    { return (_rear + 1) % _size == _front; }
     
     
    void enqueue(const T &val)
    {
        if (isFull()) {
            throw std::overflow_error("队满上溢 !");
        }
        _pQueue[_rear] = val;
        _rear = (_rear + 1) % _size;
    }
     
     
    T dequeue(void)
    {
        if (isEmpty()) {
            throw std::underflow_error("队空下溢 !");
        }
        T value = _pQueue[_front];
        _front = (_front + 1) % _size;
         
        return value;
    }
};
 
 
//
// 队列测试 
//
int main(void)
{
    CircularQueue<int> queue;
    const size_t QUEUE_SIZE = queue.getSize();
     
    for (size_t i = 0; i < QUEUE_SIZE; ++i)
    {
        queue.enqueue(i);
    }
     
    // queue.enqueue(QUEUE_SIZE);
     
    std::cout << std::endl
              << "队列" << (queue.isFull() ? "" : "不") << "为满."
              << std::endl
              << "队列" << (queue.isEmpty() ? "" : "不") << "为空."
              << std::endl;
     
    for (size_t i = 0; i < QUEUE_SIZE; ++i)
    {
        std::cout << std::setw(3) << queue.dequeue();
    }
     
    // std::cout << std::setw(3) << queue.dequeue();
     
    std::cout << std::endl
              << "队列" << (queue.isFull() ? "" : "不") << "为满."
              << std::endl
              << "队列" << (queue.isEmpty() ? "" : "不") << "为空."
              << std::endl;
               
     
     
    return EXIT_SUCCESS;
} 