Сиаод 2 Релиз

#include <iostream>
#include <string>
using namespace std;

struct element {
    char x;
    element* next = nullptr;
};

class List {
    element* head;
    int size;
public:
    List() { head = nullptr; size = 0; };
    ~List();
    char& operator[](int index);
    int pop();
    void pushBack(char x);
    void pushToHead(char x);
    void equal(List *L2);
    void cleaner();
    void print();
private:

};

char &List::operator[](int index) {
    element* current = head;
    int counter = 0;
    while (current != nullptr) {
        if (counter == index) {
            return current->x;
        }
        current = current->next;
        counter++;
    }
}

List::~List() {
    while (head != nullptr) {
        element* temp = head->next;
        delete head;
        head = temp;
    }
};

int List::pop() {
    if (size == 0) { return (int()); }
    if (size == 1) { return head->x; head = nullptr; }
    else {
        element* current = head;
        for (int i = 0; i < size - 2; i++) { current = current->next; }
        int i = (*this)[size - 1];
        current->next = current->next->next;
        size--;
        return i;
    }
}


void List::pushBack(char x) {
    size++;
    if (head == nullptr) {
        head = new element;
        head->x = x;
    }
    else {
        element* current = head;
        while (current->next != nullptr) {
            current = current->next;
        }
        current->next = new element;
        current->next->x = x;
    }
};

void List::pushToHead(char x) {
    size++;
    element* temp = new element;
    temp->x = x;
    temp->next = head;
    head = temp;
};

void List::print() {
    element* temp = head;
    while (temp != nullptr) {
        cout << temp->x << " ";
        temp = temp->next;
    }
    printf("\n");
};

void List::cleaner() {
    List* nList = new List();
    element* current = this->head;
    for (int i = 0; i < size; i++) {
        if (isalpha(current->x)) { nList->pushBack(current->x); }
        current = current->next;
    }
    *this = *nList;
}

void List::equal(List* L2) {
    bool status = true;
    if (this->size != L2->size)
    {
        status = false;
    }
    element* current1 = this->head;
    element* current2 = L2->head;

    while (current1 != nullptr && current2 != nullptr)
    {
        if (current1->x == current2->x) {
            current1 = current1->next;
            current2 = current2->next;
        }
        else {
            status = false;
        }
    }
    if (status == true) {
        cout << "EQUALITY = " << status << endl;
    }
}

int main() {
    setlocale(0, "");
    List L1;
    List L2;
    L1.pushBack('A');
    L1.pushBack('B');
    L1.pushBack('C');
    L2.pushBack('A');
    L2.pushBack('B');
    L2.pushBack('C');
    L1.equal(&L2);
    L1.print();
    L2.print();
    printf("Добавим целочисленный элемент с конца и попробуем его удалить\n");
    L1.pushBack('1');
    L1.print();
    L1.cleaner();
    L1.print();
    printf("Реализуем вставку последнего символа L2 в L1\n");
    L1.pushBack(L2.pop());
    L1.print();
    return 0;
}