Ups, I think this is better. References: http://boost.org/libs/graph/doc/connected_components.html --dima #include <boost/config.hpp> #include <boost/graph/graph_traits.hpp> // for boost::graph_traits #include <boost/graph/adjacency_list.hpp> #include <boost/graph/connected_components.hpp> #include <boost/graph/iteration_macros.hpp> /**/ struct Node { typedef int vertex_index_t; vertex_index_t m_vertex_index; static vertex_index_t Node::* svertex_index; }; Node::vertex_index_t Node::* svertex_index = &Node::m_vertex_index; struct Boundary { double something; }; typedef boost::adjacency_list< boost::setS, boost::listS, boost::undirectedS, Node, Boundary, boost::no_property, boost::setS> Graph; int main(int argc, char*argv[]) { Graph g(5); typedef boost::graph_traits<Graph>::vertex_descriptor vertex_t; std::map<vertex_t, int> comps; std::map<vertex_t, boost::default_color_type> c_m; int num = boost::connected_components(g, boost::make_assoc_property_map(comps), boost::color_map(boost::make_assoc_property_map(c_m))); std::cout << "Number of cc: " << num << std::endl; return 0; }