Re: [Boost-users] [graph] removing self-edges bug?

From: Aaron Windsor (aaron.windsor_at_[hidden])
Date: 2008-02-06 08:53:01

On Feb 6, 2008 4:39 AM, Sebastian Weber
<sebastian.weber_at_[hidden]> wrote:
> Hi everyone!
>
> I think I've hit a but in the remove_edge(u,v,bg) function in case I
> want to delete a self-edge. The following code crashes on my machine:
>
>   using namespace boost;
>   typedef adjacency_list<vecS, vecS, undirectedS > ubase_graph_t;
>
>   ubase_graph_t bg(5);
>
>   add_edge(0, 1, bg);
>   add_edge(1, 2, bg);
>   add_edge(3, 4, bg);
>   add_edge(4, 0, bg);
>   add_edge(2, 2, bg);
>
>   remove_edge(2, 2, bg);
>
> However, deleting via edge_descriptors is working:
>
>   BGL_FORALL_OUTEDGES(2, ed, bg, ubase_graph_t) {
>     if(target(ed, bg) == 2) {
>       remove_edge(ed, bg);
>       break;
>     }
>   }
>
> So what is wrong with remove_edge(u, u, bg) if there is a self-edge?

Hi Sebastian,

I can recreate the bug you're describing - this problem was actually
brought up a year ago as well, see:
http://lists.boost.org/Archives/boost/2007/02/116438.php. My reply to
that message describes what's going on. I've put in a ticket in for
this: http://svn.boost.org/trac/boost/ticket/1622. It won't be fixed
for 1.35, but should be fixed by the next release. Unfortunately, the
only workaround I can suggest is the one you've already discovered -
removing by edge descriptor.

Regards,
Aaron