Thread: Using an iterator with a vector of objects

As the title says, I'm trying to work with iterators in a class object. So far I haven't done anything beyond conventional for-loops and I'm a little uncertain on how to do this properly.

Some reduced code to show you what I'm hoping to accomplish:

Code:

struct Point { double x, y, z; };

class Helix
{
    public:
        /* here i have a constructor and some other functions
           which all work, so I'll leave it out */
        ...
        ...

        /* here I need help adding iterator functions,
            operator overloading, for the 'outside' */
        typedef std::vector<Point>::const_iterator cnst_iter;
        cnst_iter p_begin() { return point_coords.begin(); }
        cnst_iter p_end() { return point_coords.end(); }
    private:
        std::vector<Point> point_coords;
};

int main()
{
    short helices = 5; // example
    std::vector<Helix> helix;
    for(short level = 0; level < helices; level++)
    {
        helix.push_back(Helix(level, scale, density)); // works
    }

    /* here I need help:
        1) I would like to iterate over the vector of <Helix> objects.
        Do i need to define iterators inside the Helix class for this
        purpose as well, or is that only needed for private class
        members?

        2) I also want to iterate over the vector of <Point> structs
            inside the (vector of) Helix objects. I will be reading
            data only. */

    for(std::vector<Helix>::const_iterator it = helix.begin();
         it != helix.end();
         ++it;)
    {
        for(std::vector<Point>::const_iterator it2 = helix.p_begin();
             it2 != helix.p_end();
             ++it2)
        {
            /* here i need to retrieve data from
                the point_coords vector; */
        }
    }

    return 0;
}

I hope my code makes a bit of sense. I know it's wrong and I didn't try to compile it as is. I'm trying to get an idea of what key concepts and ingredients are missing.

Thanks.