template<typename T>
class Queue
{
public:
	Queue(size_t capacity = 5)
		:_front(0)
		,_rear(0)
		,_capacity(capacity+3)//加一個常數防止傳參為0程式奔潰
		,_count(0)
	{
		_pData = new T[_capacity];//開闢空間
	}
	void Push(const T& x)
	{
		if(_count != _capacity)//如果佇列不滿
		{
			_pData[_rear] = x;
			_count++;//插入後佇列中元素個數加一
			_rear = (_rear+1)%_capacity;//因為是迴圈佇列所以得模它的容量
		}
	}
	void Pop()
	{
		if(!Empty())//佇列不空
		{
			_count--;
			_front = (_front+1)%_capacity;
		}
	}
	T& Front()
	{
		return _pData[_front];
	}
	const T& Front()const
	{
		return _pData[_front];
	}
	T& Back()
	{
		return _pData[(_rear-1)%_capacity];//模容量防止_rear減完變成負數
	}
	const T& Back()const
	{
		return _pData[(_rear-1)%_capacity];
	}
	size_t Size()
	{
		return _count;
	}
	bool Empty()const
	{
		return 0 == _count;
	}
private:
	T* _pData;
	size_t _front;
	size_t _rear;
	size_t _capacity;
	size_t _count;
};

int main()
{
	Queue<int> q;
	q.Push(1);
	q.Push(2);
	q.Push(3);
	q.Push(4);
	cout<<q.Front()<<endl;
	cout<<q.Back()<<endl;
	q.Pop();
	q.Pop();
	cout<<q.Front()<<endl;
	cout<<q.Size()<<endl;
	cout<<q.Back()<<endl;
	q.Pop();
	q.Pop();
	cout<<q.Empty()<<endl;
	cout<<q.Size()<<endl;

	system("pause");
	return 0;
}
 

程式執行截圖