#include <iostream>

using namespace std;

template <typename T>
struct Iter {
    Iter() { cout << '+' << this << endl; }
    ~Iter() { cout << '-' << this << endl; }

    T ** pp {nullptr};
    int len {0};
    int it {0};

    void set(T ** pi, int l) {
        pp = pi;
        len = l;
    }
    Iter & begin() {
        it = 0;
        return *this;
    }
    int end() const {
        return len;
    }

    T & operator*() {
        return *pp[it];
    }
    bool operator!=(int rhs) {
        return this->it < rhs;
    }
    Iter & operator++() {
        ++it;
        return *this;
    }
};

class A {
public:
    A() : _len(4) {
        _ori_aa = new int [_len];
        _aa = new int * [_len];
        for(int i = 0; i < _len; i++) {
            _ori_aa[i] = i;
            _aa[i] = _ori_aa + i;
        }
    }
    ~A() {
        delete [] _aa;
        delete [] _ori_aa;
    }
    Iter<int> aa() const {
        Iter<int> _iter;
        _iter.set(_aa, _len);
        return _iter;
    }
private:
    const int _len;
    int * _ori_aa;
    int ** _aa;
};

int main() {
    A a;
    Iter<int> aa = a.aa();  // copy by value
    cout << '?' << &aa << endl;
    for(const int & n : aa) {
        cout << n << endl;
    }
    cout << "-------" << endl;
}