[Boost-users] problem with vertex properties in BGL

I have to build a graph from data in a file, some information is strings which are related to vertexes. I want to prove if those vertexes already exist in the graph before the insert operation. Next is the source: typedef adjacency_matrix UGraph; // an undirected graph UGraph g(0); // start from scratch property_map::type ename = get(edge_name, g); // not sure if this is right (the graph have no elements at this point) property_map::type vname = get(vertex_name, g); typedef property_map::type vname_type; typedef boost::property_traits::key_type vktype; typedef boost::property_traits::value_type vvtype; vktype indice_nombre; vvtype valor_nombre; for(i=0;i