Hi, there I am a new user of boost (in particular BGL). For my project, I am using the function of "prim_minimum_spanning_tree" to construct the minimum spanning tree. But I found a strange problem and hope to get your help. Specifically, I am following the sample code "prim-example.cpp" (using MSVC), with one modification to the weight property. That is, I am defining the weight property as property < edge_weight_t, float > not the original one property < edge_weight_t, int > And I found by doing so, the function of "prim_minimum_spanning_tree" return wrong results (no edge is returned at all). But the original version using "property < edge_weight_t, int >" definition works well. So I am wondering if I missed something to make user-defined weitgh property work for this function. Any suggestion is welcome. Thank you very much. Best regards, Shenai Problematic code: /////////////////////////////////////////////////////////////////////////////////////////////////// typedef adjacency_list < vecS, vecS, undirectedS, property<vertex_distance_t, int>, property < edge_weight_t, float > > Graph; typedef std::pair < int, int >E; const int num_nodes = 5; E edges[] = { E(0, 2), E(1, 1), E(1, 3), E(1, 4), E(2, 1), E(2, 3), E(3, 4), E(4, 0) }; float weights[] = { 1.0f, 2.0f, 1.0f, 2.0f, 7.0f, 3.0f, 1.0f, 1.0f }; Graph g(num_nodes); property_map<Graph, edge_weight_t>::type weightmap = get(edge_weight, g); for (std::size_t j = 0; j < sizeof(edges) / sizeof(E); ++j) { graph_traits<Graph>::edge_descriptor e; bool inserted; tie(e, inserted) = add_edge(edges[j].first, edges[j].second, g); weightmap[e] = weights[j]; } std::vector < graph_traits < Graph >::vertex_descriptor > p(num_vertices(g)); property_map<Graph, vertex_distance_t>::type distance = get(vertex_distance, g); property_map<Graph, vertex_index_t>::type indexmap = get(vertex_index, g); prim_minimum_spanning_tree(g, *vertices(g).first, &p[0], distance, weightmap, indexmap, default_dijkstra_visitor()); for (std::size_t i = 0; i != p.size(); ++i){ if (p[i] != i){ TRACE("I am here"); } } /////////////////////////////////////////////////////////////////////////////////////////////////// --------------------------------- Do You Yahoo!? 150万曲MP3疯狂搜，带您闯入音乐殿堂 美女明星应有尽有，搜遍美图、艳图和酷图 1G就是1000兆，雅虎电邮自助扩容！