List

//SLL.h

#pragma once

class List
{

public:

    int Element;

    List* Next;

    static int Count;

    static List* Head;

    static List* Tail;

    List(int InElement = 0);

    ~List();

    static bool AddFront(int InElement);

    static bool AddBack(int InElement);

    static bool RemoveFront();

    static bool RemoveBack();

    void Print();

    static void PrintAll();
};

//SLL.cpp

#include "SLL.h"
#include <iostream>

using namespace std;

List* List::Head = nullptr;
List* List::Tail = nullptr;
int List::Count = 0;

List::List(int InElement) : Element(InElement), Next(nullptr)
{
    Count++;
}
List::~List()
{
    Count--;
}

bool List::AddFront(int InElement)
{
    List* NewList = new List(InElement);

    if (!NewList)
        return false;

    if ((Head == Tail) && (Head == nullptr))
    {
        //cout << "AddFront: case 0" << endl;
        Head = NewList;
        Tail = NewList;
    }
    else
    {
        //cout << "AddFront: default" << endl;
        NewList->Next = Head;
        Head = NewList;
    }
    return true;
}

bool List::AddBack(int InElement)
{
    List* NewList = new List(InElement);

    if (!NewList)
        return false;

    if ((Head == Tail) && (Head == nullptr))
    {
        //cout << "AddFront: case 0" << endl;
        Head = NewList;
        Tail = NewList;
    }
    else
    {
        //cout << "AddFront: default" << endl;
        Tail->Next = NewList;
        Tail = NewList;
    }
    return true;
}

bool List::RemoveFront()
{
    if (!Head)
        return false;

    List* ToDelete = Head;
    if (ToDelete == Tail)
    {
        Tail = nullptr;
        Head = nullptr;
    }
    else
    {
        Head = Head->Next;
    }

    delete ToDelete;

    return true;
}

bool List::RemoveBack()
{
    if (!Tail)
        return false;

    List* ToDelete = Tail;
    if (ToDelete == Head)
    {
        Tail = nullptr;
        Head = nullptr;
    }
    else
    {
        List* BeforeTail = Head;
        while (BeforeTail->Next != Tail)
        {
            BeforeTail = BeforeTail->Next;
        }
        Tail = BeforeTail;
        BeforeTail->Next = nullptr;
    }

    delete ToDelete;

    return true;
}

void List::Print()
{
    cout << "Element = " << Element << endl;
    if (Next)
    {
        Next->Print();
    }
    else
    {
        cout << "Last element\n";
    }
}

void List::PrintAll()
{
    if (Head)
    {
        Head->Print();
    }
    else
    {
        cout << "List is empty\n";
    }
}

//Main.cpp

#include <iostream>
#include "SLL.h"

using namespace std;

int main()
{
    //List* L = new List(5);
    List::AddFront(4);
    List::AddFront(5);
    List::AddBack(3);

    List::PrintAll();

    List::RemoveBack();

    List::PrintAll();

    List::RemoveFront();

    List::PrintAll();

    List::RemoveFront();

    List::PrintAll();

    system("pause");
    return 0;
}