void List::operator+=(int key)
{
    this->addToEnd(key);
}

void List::operator+=(ListElement& element)
{
    this->addToEnd(ListElement * element);
}

void List::operator+=(ListElement* element)
{
    this->addToEnd(ListElement *element);
}

void List::operator-=(int key)
{
    this->removeKey(key);
}

void List::operator-=(ListElement& element)
{
    this->removeKey(element->getKey());
}

void List::operator-=(ListElement* element)
{
    this->removeKey(element->getKey());
}

bool List::operator== (List& otherList)
{
    bool control;

    if (sizeof(this) == sizeof(otherList))
    {
        while (this->next != NULL)
        {
            control = 0;

            while (otherList->next != NULL)
            {
                if (this->getKey() == otherList->getKey())
                {
                    control = 1;
                }
                otherList = otherList->next;
            }

            if (!control)
            {
                return 0;
            }
            this = this->next;
        }

        return 1;
    }
    else
    {
        return 0;
    }
}

bool List::operator!= (List& otherList)
{
    bool control;

    if (sizeof(this) != sizeof(otherList))
    {
        while (this->next != NULL)
        {
            control = 1;

            while (otherList->next != NULL)
            {
                if (this->getKey() == otherList->getKey())
                {
                    control = 0;
                }
                otherList = otherList->next;
            }

            if (!control)
            {
                return 0;
            }
            this = this->next;
        }

        return 1;
    }
    else
    {
        return 0;
    }
}