Re: [boost] [iterator] counting_iterator and reverse iterator problem (was: [graph][iterators] csr graph and reverse iterator problem)

Subject: Re: [boost] [iterator] counting_iterator and reverse iterator problem (was: [graph][iterators] csr graph and reverse iterator problem)
From: Jeremiah Willcock (jewillco_at_[hidden])
Date: 2011-09-07 15:55:26

On Wed, 7 Sep 2011, Takatoshi Kondo wrote:

> Hi, All
>
> I'm using Boost.Graph and Boost.Iterators.
>
> When I use the compressed_sparse_row_graph with reverse_iterator,
> I ran into a problem.
>
> When I dereference the reverse_iterator of
> compressed_sparse_row_graph's iterator, invalid memory access occurs.

I tried my copy of GCC 4.6, and get a similar problem.  It does not seem 
to related to Boost.Graph at all, though; I get the same result (use of 
uninitialized value) with counting_iterators that are created directly 
(CSR graph vertex_iterators are counting_iterators).  I changed the 
subject line to emphasize the Boost.Iterator issue.  Here is a 
trimmed-down program that has similar problems, even with optimization 
disabled:

#include <boost/iterator/reverse_iterator.hpp>
#include <boost/iterator/counting_iterator.hpp>
#include <iostream>

int main() {
   boost::counting_iterator<int> ie(2);
   boost::reverse_iterator<boost::counting_iterator<int> > rib(ie);
   std::cout << *rib << std::endl;
   return 0;
}

-- Jeremiah Willcock