reinterpret

class A {
public:
	int a;
};

class AA : public A {
public:
	int b;
};

int main() {
	A* a = new A();
	a->a = 5;
	AA* aa = reinterpret_cast<AA*>(a);
	cout << aa->a << endl;
	cout << aa->b << endl;
	aa->a = 6;
	aa->b = 7;
	cout << aa->a << endl;
	cout << aa->b << endl;
    return 0;
}