Re: How to print container elements which are pointers

On Thursday, November 8, 2012 8:36:30 PM UTC-6, V.Subramanian, India wrote:


To expose a pointer-based interface is very dangerous, since it's too
easy to leak a new-ed memory (your sample program already leaked) or
encounter a data corruption if you insist to delete the pointers
somewhere.

Anyway, here is my suggestion: to define a custom iterator.

First, as usual, you need an output operator for Person:

friend ostream& operator<<(ostream& out, Person const& p) {
    out << p.name;
    return out;
}

And then, a proxy-like iterator in Club:

class Club {

public:
struct iterator : list<Person>::iterator {
    explicit iterator(list<Person*>::iterator i) : ptr_(i) {}

    iterator(iterator const& i) : ptr_(i.ptr_) {}

    iterator& operator=(iterator i) {
        using std::swap;
        swap(this->ptr_, i.ptr_);
        return *this;
    }

    reference operator*() const {
        return **ptr_;
    }

    pointer operator->() const {
        return &(operator*());
    }

    iterator& operator++() {
        ++ptr_;
        return *this;
    }

    iterator operator++(int) {
        iterator tmp(*this);
        ++(*this);
        return tmp;
    }

    /* operator-- omitted */

    friend bool operator==(iterator x, iterator y) {
        return x.ptr_ == y.ptr_;
    }

    friend bool operator!=(iterator x, iterator y) {
        return !(x == y);
    }

private:
    list<Person*>::iterator ptr_;
};
list<Person*> officers;

iterator begin() {
    return iterator(officers.begin());
}

iterator end() {
    return iterator(officers.end());
}
};

So that you can use

copy(c.begin(),
     c.end(),
     ostream_iterator<Person>(cout, "\n"));

To print the Club. Cool?