只写了int类型，代码感觉还可以再优化，至于用模板则还要学习; 简单起见,全写在了一个cpp文件中

//double linked list (type int)
#include <iostream>
using namespace std;

class Node
{
public:
    Node() {};
    Node(int val) {
        this->val =val;
        prior = next = nullptr;
    }
    ~Node() {};

    void setVal(int val) { this->val = val; }
    int getVal() {
        return this->val;
    }

    Node* prior;   //指向前节点指针
    Node* next;   //指向后节点指针
    
private:
    int val=0;
};


class DLlist
{
public:

    DLlist(int size) {
        this->size = size;
        head = new Node;
        head->prior = nullptr;
        head->next = nullptr;
        tail = head;
        for (int i = 0; i < this->size; i++)
        {
            int v;
            cout << "Enter the value of No. " << i +1<< " Node: ";
            cin >> v;
            if (i==0)
            {
                head->setVal(v);
            }
            else
            {
                Node* temp=new Node;
                temp->setVal(v);
                temp->next = nullptr;
                temp->prior = tail;
                tail->next = temp;
                tail = temp;
            }
        }
    }
    ~DLlist() { Clear(); }


    int getSize()
    {
        return this->size;
    }

    void insert(int num,int pos)   //在两节点间插入，插入位置的前后节点必须都存在
    {
        Node* temp = new Node;
        Node* position;
        temp->setVal(num);
        position = GetPointer(pos);
        (position->prior)->next = temp;
        temp->next = position;
        temp->prior = position->prior;
        position->prior = temp;
        size++;
    }

    void deleteList(int pos)   //删除节点，删除位置的前后节点必须都存在
    {
        Node* position;
        position = GetPointer(pos);
        (position->prior)->next = position->next;
        (position->next)->prior = position->prior;
        delete position;
        size--;
    }

    void addFirst(int element)     //pushFront
    {
        
        if (head == nullptr)
        {
            head->setVal(element);
            head->prior = nullptr;
            head->next = nullptr;
            tail = head;
            size++;
        }
        else 
        {
            /*我们要在头结点前再插入一个结点，需要先创建一个新的结点，将头结点的值保存在新节点，然后让新节点的下
            个结点指向头结点的下一个结点，再让新节点的prior指向头结点，这样就将新节点与原来的链表融合了，然后我  
            们将头结点的数据换成element即可*/
            
            Node* temp=new Node;
            temp->setVal(head->getVal());
            temp->next = head->next;
            temp->prior = head;
            if (size > 1)
            {
                (head->next)->prior = temp;
            }
            head->next = temp;
            head->setVal(element);
            size++;
        }
    }

    void addLast(int element)   //pushBack
    {
        
        if (head==nullptr)
        {
            head->setVal(element);
            head->prior = nullptr;
            head->next = nullptr;
            tail = head;
            size++;
        }
        else
        {
            Node* temp = new Node;
            temp->setVal(tail->getVal());
            temp->prior = tail->prior;
            temp->next = tail;
            if (size-1!=0)
            {
                (tail->prior)->next = temp;
            }
            tail->prior = temp;
            tail->setVal(element);
            size++;
        }
    }

    int removeFirst()
    {
        int v = head->getVal();

        head = head->next;
        if (size > 1)
        {
            head->prior = nullptr;
        }

        size--;
        return v;
        
    }

    int removeLast()
    {
        int v = tail->getVal();
        
        tail =tail->prior;
        if (size>1)
        {
            tail->next = nullptr;
        }

        size--;
        return v;
    }

    int returnNth(int pos)
    {
        return GetPointer(pos)->getVal();
    }

    bool isEmpty()
    {
        if (size==0)
        {
            return true;
        }
        else
        {
            return false;
        }
    }

    void printList()
    {
        for (int i = 0; i < size; i++)
        {
            cout << "No. " << i +1<< " = " << GetPointer(i)->getVal() << endl;
        }
    }

    
    void Clear()
    {
        while (head != nullptr)
        {
            Node * temp = head->next;
            delete head;
            head = temp;
        }
        tail = nullptr;
        size = 0;
    }

private:
    int size = 0;
    Node* head;  //指向头节点的指针
    Node* tail;     //指向尾节点的指针

    Node* GetPointer(int pos)   //查找节点
    {
        Node* pNode = nullptr;
        if (pos<0 || pos>size-1)
        {
            cout << "Out of range! " << endl;
        }
        else
        {
            pNode = head;
            for (int i = 0; i < pos; i++)
            {
                pNode = pNode->next;
            }
            return pNode;
        }
    }
};

int main()
{
    DLlist d(3);
    cout << endl;
    cout << "Size: " << d.getSize() << endl;
    d.printList();
    cout << endl;

    cout << "Insert 10 at position 1" << endl;
    d.insert(10, 1);
    cout << "Size: " << d.getSize() << endl;
    d.printList();

    cout << endl;
    cout << "Addfirst 100" << endl;
    d.addFirst(100);
    cout << "Now No.1's value= " << d.returnNth(0) << endl;

    cout << endl;
    cout << "Remove first" << endl;
    d.removeFirst();
    d.printList();

    cout << endl;
    cout << "Remove last" << endl;
    d.removeLast();
    d.printList();

    cout << endl;
    d.~DLlist();
    cout << "Empty: " <<boolalpha<< d.isEmpty() << endl;

    system("pause");
    return 0;
}