On Fri, 20 Aug 2010, John Robertson wrote:
I'm trying to obtain an iterator of edges with a different ordering than that given in egdes(g).
The following compiles but segfaults at std::sort( VE.begin(), VE.end(), ordering< Graph, edd >() ); (runs ok if the above line is commented out)
////////////////////////////////////////////////////////////////////////////////////////////////////////////////
typedef Traits::edge_descriptor edd;
// Create ordering template < typename Graph, typename edd > struct ordering { Graph & g; bool operator ()(const edd & a, const edd & b) { return g[a].eName < g[b].eName; } };
template < typename Graph > int initialize_container( Graph & g ) {
typename graph_traits<Graph>::edge_iterator edge_iter, edges_end;
// create vector of edge descriptors. std::vector< Traits::edge_descriptor > VE(num_edges(g)+1);
int i = 1; // (Sometimes I like to start at 1.)
//insert edge descriptors into vector of edge descriptors. for (tie(edge_iter, edges_end) = edges(g); edge_iter != edges_end; ++edge_iter) { cout << " *edge_iter = " << *edge_iter << endl; VE[i++] = *edge_iter; }
// segfaults here //sort vector of edge descriptors. std::sort( VE.begin(), VE.end(), ordering< Graph, edd >() );
//print sorted edge descriptors. for( int i = 1; i < num_edges(g)+1; ++i ) cout << " -Edge " << i << " = " << VE[i] << endl;
}
What is edd (i.e., what members does it have)? Also, if you are indexing from 1, you should sort from VE.begin() + 1 to VE.end() to skip the uninitialized element 0. -- Jeremiah Willcock