Thank you for the hint. I've overseen that. But beside that there must be another mistake, because it crashes again after that slight change of the code. Douglas Gregor schrieb:

----- Original Message ----- From: "Stephan Höfer"

...

Graph tSubGraph = g.create_subgraph();

Ah ha! You want:

Graph& tSubGraph = g.create_subgraph();

The root graph actually allocates a new child in its own memory space in create_subgraph(), and then gives you a reference to the subgraph. What's happening here is that subgraph is getting double-freed. Yes, we should do something to protect against this.

Doug

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the original graph looks like that 0--1--2--3 | | | | 7--6--5--4 the subgraph looks like that 0--1--2 | | 6--5 typedef boost::property > VertexProperty; typedef boost::property > > EdgeProperty; typedef boost::subgraph< boost::adjacency_list > Graph; void main() { Graph g(7); boost::property_map::type weightmap = boost::get(boost::edge_weight, g); Edge e; bool inserted; boost::tie(e, inserted) = boost::add_edge(0, 1, g); weightmap[e] = 1; boost::tie(e, inserted) = boost::add_edge(1, 2, g); weightmap[e] = 1; boost::tie(e, inserted) = boost::add_edge(2, 3, g); weightmap[e] = 1; boost::tie(e, inserted) = boost::add_edge(3, 4, g); weightmap[e] = 1; boost::tie(e, inserted) = boost::add_edge(4, 5, g); weightmap[e] = 1; boost::tie(e, inserted) = boost::add_edge(5, 2, g); weightmap[e] = 1; boost::tie(e, inserted) = boost::add_edge(5, 6, g); weightmap[e] = 1; boost::tie(e, inserted) = boost::add_edge(6, 1, g); weightmap[e] = 1; boost::tie(e, inserted) = boost::add_edge(6, 7, g); weightmap[e] = 1; boost::tie(e, inserted) = boost::add_edge(7, 0, g); weightmap[e] = 1; Graph& tSubGraph = g.create_subgraph(); add_vertex(0,tSubGraph); add_vertex(1,tSubGraph); add_vertex(2,tSubGraph); add_vertex(5,tSubGraph); add_vertex(6,tSubGraph); std::vector < boost::graph_traits < Graph >::vertex_descriptor> p(boost::num_vertices(tSubGraph)); boost::prim_minimum_spanning_tree(tSubGraph, &p[0]); } The crash happens after having added for instance the 6th point of the Graph g to the subgraph. Before it worked. Jeremy Siek schrieb:

I haven't been following the thread, but if you post a small (less than one page) but complete example program that exhibits the crash I'd be willing to take a look.

Cheers, Jeremy

On Tuesday, August 5, 2003, at 02:21 AM, Stephan Höfer wrote:

...

Thank you for the hint. I've overseen that. But beside that there must be another mistake, because it crashes again after that slight change of the code.

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Now I've completed the program. Some BGL includes were missing and two typedefs. I was able to compile this little program with the VC++ .net compiler. It crashes as described after adding the vertex 6 to the subgraph. Even for other vertices this happend. #include // put this first to suppress some VC++ warnings #include #include #include #include typedef boost::adjacency_list_traits< boost::vecS, boost::vecS, boost::undirectedS >::vertex_descriptor vertex_descriptor; typedef boost::property > VertexProperty; typedef boost::property > > EdgeProperty; typedef boost::subgraph< boost::adjacency_list > Graph; typedef boost::graph_traits < Graph >::edge_descriptor Edge; int main(void) { Graph g(7); boost::property_map::type weightmap = boost::get(boost::edge_weight, g); Edge e; bool inserted; boost::tie(e, inserted) = boost::add_edge(0, 1, g); weightmap[e] = 1; boost::tie(e, inserted) = boost::add_edge(1, 2, g); weightmap[e] = 1; boost::tie(e, inserted) = boost::add_edge(2, 3, g); weightmap[e] = 1; boost::tie(e, inserted) = boost::add_edge(3, 4, g); weightmap[e] = 1; boost::tie(e, inserted) = boost::add_edge(4, 5, g); weightmap[e] = 1; boost::tie(e, inserted) = boost::add_edge(5, 2, g); weightmap[e] = 1; boost::tie(e, inserted) = boost::add_edge(5, 6, g); weightmap[e] = 1; boost::tie(e, inserted) = boost::add_edge(6, 1, g); weightmap[e] = 1; boost::tie(e, inserted) = boost::add_edge(6, 7, g); weightmap[e] = 1; boost::tie(e, inserted) = boost::add_edge(7, 0, g); weightmap[e] = 1; Graph& tSubGraph = g.create_subgraph(); boost::add_vertex(0,tSubGraph);boost::add_vertex(1,tSubGraph); boost::add_vertex(2,tSubGraph);boost::add_vertex(5,tSubGraph); boost::add_vertex(6,tSubGraph); std::vector < boost::graph_traits < Graph >::vertex_descriptor> p(boost::num_vertices(tSubGraph)); boost::prim_minimum_spanning_tree(tSubGraph, &p[0]); } Cheers, Stephan Jeremy Siek schrieb:

Hi Stephan,

What you've posted is not a complete program (it is missing at least the #include's). Please post a complete program.

Thanks, Jeremy

P.S. Sorry to be pedantic about this, but I've wasted a lot of time in the past trying to reconstruct complete programs from incomplete programs.

On Wed, 6 Aug 2003, Stephan [iso-8859-1] Höfer wrote: yg-boo> the original graph looks like that yg-boo> yg-boo> 0--1--2--3 yg-boo> | | | | yg-boo> 7--6--5--4 yg-boo> yg-boo> the subgraph looks like that yg-boo> 0--1--2 yg-boo> | | yg-boo> 6--5 yg-boo> yg-boo> typedef boost::property boost::property< boost::vertex_predecessor_t, vertex_descriptor > > yg-boo> VertexProperty; yg-boo> yg-boo> typedef boost::property boost::property boost::property > > EdgeProperty; yg-boo> yg-boo> typedef boost::subgraph< boost::adjacency_list boost::undirectedS, yg-boo> VertexProperty, EdgeProperty > > Graph; yg-boo> yg-boo> void main() yg-boo> { yg-boo> Graph g(7); yg-boo> yg-boo> boost::property_map::type weightmap = yg-boo> boost::get(boost::edge_weight, g); yg-boo> Edge e; bool inserted; yg-boo> yg-boo> boost::tie(e, inserted) = boost::add_edge(0, 1, g); weightmap[e] = 1; yg-boo> boost::tie(e, inserted) = boost::add_edge(1, 2, g); weightmap[e] = 1; yg-boo> boost::tie(e, inserted) = boost::add_edge(2, 3, g); weightmap[e] = 1; yg-boo> boost::tie(e, inserted) = boost::add_edge(3, 4, g); weightmap[e] = 1; yg-boo> boost::tie(e, inserted) = boost::add_edge(4, 5, g); weightmap[e] = 1; yg-boo> boost::tie(e, inserted) = boost::add_edge(5, 2, g); weightmap[e] = 1; yg-boo> boost::tie(e, inserted) = boost::add_edge(5, 6, g); weightmap[e] = 1; yg-boo> boost::tie(e, inserted) = boost::add_edge(6, 1, g); weightmap[e] = 1; yg-boo> boost::tie(e, inserted) = boost::add_edge(6, 7, g); weightmap[e] = 1; yg-boo> boost::tie(e, inserted) = boost::add_edge(7, 0, g); weightmap[e] = 1; yg-boo> yg-boo> Graph& tSubGraph = g.create_subgraph(); yg-boo> yg-boo> add_vertex(0,tSubGraph); add_vertex(1,tSubGraph); add_vertex(2,tSubGraph); yg-boo> add_vertex(5,tSubGraph); add_vertex(6,tSubGraph); yg-boo> yg-boo> std::vector < boost::graph_traits < Graph >::vertex_descriptor> yg-boo> p(boost::num_vertices(tSubGraph)); yg-boo> boost::prim_minimum_spanning_tree(tSubGraph, &p[0]); yg-boo> } yg-boo> yg-boo> The crash happens after having added for instance the 6th point of the Graph yg-boo> g to the subgraph. Before it worked. yg-boo>

---------------------------------------------------------------------- Jeremy Siek http://php.indiana.edu/~jsiek/ Ph.D. Student, Indiana Univ. B'ton email: jsiek@osl.iu.edu C++ Booster (http://www.boost.org) office phone: (812) 855-3608 ----------------------------------------------------------------------

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