用首位相接的数组仿stl双端队列deque

这是stl deque的测试 仅实现部分功能

这是利用首位相接的数组 [循环队列]仿stl双端队列deque

将得到一样的结果

#include<iostream>
#include<unordered_map>
using namespace std;
template<class T>
class Deque
{
	int start, rear;
	T* elements;
	int maxsize ;
public:
	Deque();
	~Deque() { delete[]elements; }
	bool empty();
	bool isfull();
	void clear();
	int front();
	int back();
	void push_back(int x);
	void push_front(int x);
	void pop_back();
	void pop_front();
	int at(int x);
	T operator[](int x);
};
template<class T>
Deque<T>::Deque()
{
	maxsize = 100;
	elements = new T[maxsize];
	start = rear = 0;
}
template<class T>
bool Deque<T>::empty()
{
	if (start == rear)
		return true;
	return false;
}
template<class T>
bool Deque<T>::isfull()
{
	if ((rear+1)%maxsize== start)
		return true;
	return false;
}
template<class T>
void Deque<T>::clear()
{
	start = rear = 0;
}
template<class T>
int Deque<T>::front()
{
	if (!empty())
		return elements[start];
	else
		cout << "队列为空" << endl;
}
template<class T>
int Deque<T>::back()
{
	if (!empty())
	{
		int temp = (rear - 1 + maxsize) % maxsize;
		return elements[temp];
	}
	else
		cout << "队列为空" << endl;
}
template<class T>
void Deque<T>::push_back(int x)
{
	if (!isfull())
	{
		elements[rear] = x;
		rear=(rear+1+maxsize)%maxsize;
	}
	else
		cout << "队列已满，不能从尾部插入" << endl;
}
template<class T>
void Deque<T>::push_front(int x)
{
	if (isfull())
		cout << "队列已满，不能从头部插入" << endl;
	else {
		start = (start - 1 + maxsize) % maxsize;
		elements[start] = x;
	}

}
template<class T>
void Deque<T>::pop_back()
{
	if (empty())
		cout << "队列为空，不能删除" << endl;
	else
	{
		rear = (rear - 1 + maxsize) % maxsize;
	}
}
template<class T>
void Deque<T>::pop_front()
{
	if (empty())
		cout << "队列为空，不能删除" << endl;
	else
	{
		start = (start + 1 + maxsize) % maxsize;
	}
}
template<class T>
int Deque<T>::at(int x)
{
	int r = (start + x + maxsize) % maxsize;
	return elements[r];
}
template<class T>
T Deque<T>::operator[](int x)
{
	return elements[(start + x+maxsize)%maxsize];
}
int main()
{
	Deque<int>q;
	q.push_back(3);
	q.push_back(4);
	q.push_back(5);
	q.push_back(6);
	q.push_front(7);
	cout << q.front() << endl;
	cout << q.back() << endl;
	cout << q.at(3) << endl;
	cout << q[0] << endl;
	q.empty();
	q.pop_back();
	q.pop_front();
	cout << q.front() << endl;
	cout << q.back() << endl;
}