Re: [Boost-users] [Iterators] iterators over char *

Subject: Re: [Boost-users] [Iterators] iterators over char *
From: Krzysztof Czainski (1czajnik_at_[hidden])
Date: 2010-11-02 06:04:13

2010/11/2 Rao, Anant <Anant.Rao_at_[hidden]>:
> While it’s true that a char* seems to be equivalent to an iterator (in this
> case), I prefer the iterator/reverse_iterator much better. For example, if I
> use an iterator and it reaches end(), I can do
> --it to  get to the last char.
> In a char * model, once I reach the NULL ptr (at the end of the string), I
> can’t back-track.

I think You are confusing NULL pointer with null character.

> Similarly, rbegin()/reverse_iter. Maintaining a sentinel
> value for the start of a string is more difficult (other than indices).
> IMHO, those are the solid advantages I see with an iterator.
>
> I re-read the article published by David Abrahams et al on
> ‘reverse_iterator’
> (http://www.boost.org/doc/libs/1_44_0/libs/iterator/doc/reverse_iterator.html_)
>
> and felt it’s adequate for my purposes. Basically, I will use that
> reverse_iterator for both fwd and reverse traversals by using ++ and --.

I think You are confusing bidirectional iterator with reverse iterator

> A  couple  of simple questions I have:
>
> -          Why is it not possible to define a boost::iterator as easily as a
> boost::reverse_iterator on a char * string  as in the above web link?
> (Again, it doesn’t block me – as I mentioned, I’ll just use a reverse_iter
> and use ++ and – on it to satisfy my needs. More of curiosity).

Because char* is an iterator itself.

> -          Looks like boost::reverse_iterator can’t be assigned to; can only
> be created. If I need to define it as a class member that needs to be made
> to point to diff strings as the program progresses, it doesn’t seem to be
> possible. So, I’m thinking of using a ptr to a boost::reverse_iterator so
> that I can re-seat the reverse_iterator to diff strings. Is this a
> convoluted approach or correct approach (given my needs)? If former, what’d
> be the correct approach?

I think it can be assigned to, but that is irrelevant, because You
don't seem to need it anyway.

Regards,
Kris.