Re: [Boost-users] [BGL] assert( source(* (out_edges(v, undigraph).first), undigraph) == v )

On Fri, 17 May 2013, Andreas Fabri wrote:

Hello,

When I have an undirected graph, for edge_descriptor source and target still are defined.

That is stated here: http://www.boost.org/doc/libs/1_53_0/libs/graph/doc/graph_concepts.html

My question. Is

edge_descriptor ed = * out_edges(v,undigraph).first;

Is there a requirement for graph implementations that source(ed,g) == v ?

Yes -- see http://www.boost.org/doc/libs/1_53_0/libs/graph/doc/IncidenceGraph.html#sec:.... -- Jeremiah Willcock