On Jan 29, 2007, at 2:38 PM, Adrian Boeing wrote:

Hi Jens,

Unfortunately it's all part of a larger program so I can't easily provide a small example.

Yes, I am using the vecS storage: typedef boost::adjacency_list,boost::property,boost::no_property, boost::listS > graph_type;

I'm not sure how to remove the property descriptor, there does not seem to be a boost::remove(vertex prop,graph) that I can find anywhere.

Hmmm. So, when one removes a vertex from an adjacency_list with VertexListS=vecS, it actually invalidates all of the existing vertex descriptors. So simple code like the following causes problems: graph_type::vertex_descriptor u = *vertices(g).first; graph_type::vertex_descriptor v = *(++vertices(g).first); clear_vertex(u, g); remove_vertex(u, g); adjacent_vertices(v, g); // v has been invalidated vecS is a tricky beast. I usually recommend avoiding the removal of vertices when VertexListS=vecS... it's inefficient and hard to use properly. Cheers, Doug

Hello, Yes, I've been finding strange problems but as Doug mentioned, it's hard to use properly, so instead of removing them I am just clearing the vertex. (ie: clear_vertex(u, g);) It makes it a bit more annoying to use the graph, but at least I get no more crashes; and programing around the empty vertices is easier than trying to remove them from the graph. Cheers, -Adrian Leandro Melo wrote:

Hi.

I had similar problems. Unfortunately, I can't remember right now what the particular situation was. I wrote the code in different ways (because of the invalidation process), but still my program crashed. Then I tried running the same code on GCC (in a debian machine). For my surprise, the problem no longer happened.

Leandro Melo

On 1/29/07, Doug Gregor wrote:

...

On Jan 29, 2007, at 2:38 PM, Adrian Boeing wrote:

...

Hi Jens,

Unfortunately it's all part of a larger program so I can't easily provide a small example.

Yes, I am using the vecS storage: typedef boost::adjacency_list,boost::property,boost::no_property, boost::listS > graph_type;

I'm not sure how to remove the property descriptor, there does not seem to be a boost::remove(vertex prop,graph) that I can find anywhere. Hmmm. So, when one removes a vertex from an adjacency_list with VertexListS=vecS, it actually invalidates all of the existing vertex descriptors. So simple code like the following causes problems:

graph_type::vertex_descriptor u = *vertices(g).first; graph_type::vertex_descriptor v = *(++vertices(g).first); clear_vertex(u, g); remove_vertex(u, g); adjacent_vertices(v, g); // v has been invalidated

vecS is a tricky beast. I usually recommend avoiding the removal of vertices when VertexListS=vecS... it's inefficient and hard to use properly.

Cheers, Doug

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