Letters

#include <iostream>

using namespace std;

class A {
private:
    int x;

public:
    A(int x = 0) {
        if (x > 2) {
            throw (int) 1;
        }
        this->x = x;
    }

    static const int year;

    virtual ~A() {}
};

const int A::year = 4;

class B : public A {
private:
    int y;

public:
    B(int x = 0, int y = 0) : A(x) { this->y = y; }

    ~B() {}
};

class C : public A {
private:
    int z;
public:
    C(int x = 0, int z = 0) : A(x) { this->z = z; }

    void print() {
        cout << "I am from C." << endl;
    }


};

/*
 * Virtual - makes the base pointer point to the derived function
 * Pure Virtual = Interface, forces you to inherit, makes the base class abstract meaning you can not make objects of it
*/

class Book {
private:
    A **letters;
    int len;
public:
    Book() {
        letters = NULL;
        len = 0;
    }

    void print() {
        int bs = 0;
        int cs = 0;
        for (int i = 0; i < len; ++i) {
            A *b = dynamic_cast<B *>(letters[i]);
            if (b) { bs++; }
            A *c = dynamic_cast<C *>(letters[i]);
            if (c) { cs++; }
        }
        cout << "B: " << bs << endl;
        cout << "C: " << cs << endl;
    }

    Book &operator+=(A *a) {
        A **old = letters;
        letters = new A *[len + 1];
        for (int i = 0; i < len; ++i) {
            letters[i] = old[i];
        }
        letters[len++] = a;
        delete[] old;
        return *this;
    }

    Book &operator=(const Book &b) {
        if (this == &b) return *this;
        /* Delete old objects in this */
        for (int i = 0; i < len; ++i) {
            delete[] letters[i];
        }
        delete[] letters;
        letters = new A *[b.len + 1];
        for (int j = 0; j < len; ++j) {
            letters[j] = b.letters[j];
        }
        len = b.len;
        return *this;
    }
};

int main() {
    B *ptrB = new B(5, 6);
    C *ptrC = new C(7, 3);
    C *ptrC2 = new C(1, 9);
    A *ptr[] = {ptrB, ptrC, ptrC2};

    try {
        A a(3);
        cout << a.year << endl;
    } catch (int){
        cerr << "fuck/n";
    }

    Book book;
    book += new B(5, 6);
    book += new C(5, 6);
    book += new C(5, 6);
    book += new B(5, 6);
    book.print();
    return 0;
}