Re: [Boost-users] Confused with BGL-- Six Degrees of KevinBaconexample

Dear Jeremiah Willcock, Thanks for your explanations. I think I am starting to walk out of the chaos... For the adjacency_list, there isn't an edge_index property. That means the edge_index property is not used by the graph internally, but could be used by user just like the edge_weight or edge_name, and these property should be assgined by user manually. So in the examples "exterior_properties.cpp", I could replace all the strings "edge_index" with "edge_weight", and doing this will not affect the result. The property map works in this case beacuse the edge_index property is type of int, and the value of the edge_index property is the offset to the beginning of the underlying property containers (int capacity[] and int flow[]). And the whole mapping process when calling the "boost::get(capacity, *out)" includes two mappings: Frist mapping: KEY=*out (edge descriptor)-->VALUE = offset value (int) Second mapping: KEY=offset value (int) --> VALUE= the corresponding property value Am I right? Thanks. Zhiyu LI "exterior_properties.cpp": typedef boost::adjacency_list > Graph; int capacity[] = { 10, 20, 20, 20, 40, 40, 20, 20, 20, 10 }; int flow[] = { 8, 12, 12, 12, 12, 12, 16, 16, 16, 8 }; boost::add_edge(0, 1, 0, G); boost::add_edge(1, 4, 1, G); ... typedef boost::property_map::type EdgeIndexMap; EdgeIndexMap edge_id = boost::get(boost::edge_index, G); boost::iterator_property_map capacity_array(capacity, edge_id), flow_array(flow, edge_id); print_network(G, capacity_array, flow_array); inside the function print_network: boost::get(capacity, *out) ...