Doubly Linked List

#include <iostream>

using namespace std;

class Node {
    private:
        Node();
        Node(string s, Node* p, Node* n);
        string body;
        Node* prev;
        Node* next;
    friend class DoublyLinkedList;
};

Node::Node(){
};

Node::Node(string s, Node* p, Node* n){
    body = s;
    prev = p;
    next = n;
};

class DoublyLinkedList{
    public:
        DoublyLinkedList();
        ~DoublyLinkedList();
        void AddInFront(string s);
        void RemoveInFront();
        void AddInBack(string s);
        void RemoveInBack();
        void ShowAll();
    private:
        Node* head;
        Node* trail;
};

DoublyLinkedList::DoublyLinkedList(){
    head = new Node();
    trail = new Node();
    head->next = trail;
    trail->prev = head;
};

DoublyLinkedList::~DoublyLinkedList(){
    while (head->next != trail){
        RemoveInFront();
    }
    delete head;
    delete trail;
};

void DoublyLinkedList::AddInFront(string s){
    Node* nxFrontNode = head->next;
    Node* n = new Node(s, head, head->next);
    head->next = n;
    nxFrontNode->prev = n;
};

void DoublyLinkedList::RemoveInFront(){
    if(head->next != trail){
        Node* nxFrontNode = head->next;
        Node* nnxFrontNode = nxFrontNode->next;
        head->next = nnxFrontNode;
        nnxFrontNode->prev = head;
        delete nxFrontNode;
    }
};

void DoublyLinkedList::AddInBack(string s){
    Node* nxBackNode = trail->prev;
    Node* n = new Node(s, trail->prev, trail);
    trail->prev = n;
    nxBackNode->next = n;
};

void DoublyLinkedList::RemoveInBack(){
    if(trail->prev != head){
        Node* nxBackNode = trail->prev;
        Node* nnxBackNode = nxBackNode->prev;
        trail->prev = nnxBackNode;
        nnxBackNode->next = trail;
        delete nxBackNode;
    }
};

void DoublyLinkedList::ShowAll(){
    Node* n = head->next;
    while(n != trail){
        cout << n -> body << endl;
        n = n -> next;
    }
}

int main()
{
    cout << "- Doubly Linked List exercise -" << endl;

    cout << "Create a new DoublyLinkedList: " << endl;
    DoublyLinkedList myDoublyLinkedList;
    myDoublyLinkedList.ShowAll();
    cout << endl;

    cout << "Remove nothing in a empty Doubly Linked List: " << endl;
    myDoublyLinkedList.RemoveInFront();
    myDoublyLinkedList.ShowAll();
    cout << endl;

    cout << "Insert something in Front: " << endl;
    myDoublyLinkedList.AddInFront("ABC");
    myDoublyLinkedList.AddInFront("DEFGH");
    myDoublyLinkedList.AddInFront("I");
    myDoublyLinkedList.AddInFront("JK");
    myDoublyLinkedList.AddInFront("LMN");
    myDoublyLinkedList.ShowAll();
    cout << endl;

    cout << "Remove something in Front: " << endl;
    myDoublyLinkedList.RemoveInFront();
    myDoublyLinkedList.RemoveInFront();
    myDoublyLinkedList.ShowAll();
    cout << endl;

    cout << "Insert something in Back: " << endl;
    myDoublyLinkedList.AddInBack("RST");
    myDoublyLinkedList.AddInBack("UVW");
    myDoublyLinkedList.AddInBack("XYZ");
    myDoublyLinkedList.ShowAll();
    cout << endl;

    cout << "Remove something in Back: " << endl;
    myDoublyLinkedList.RemoveInBack();
    myDoublyLinkedList.RemoveInBack();
    myDoublyLinkedList.ShowAll();
    cout << endl;

    cout << "end!" << endl;
    return 0;
}