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

Subject: Re: [Boost-users] [BGL] assert( source(* (out_edges(v, undigraph).first), undigraph) == v )
From: Jeremiah Willcock (jewillco_at_[hidden])
Date: 2013-05-17 11:18:56

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:out-edges>.

-- Jeremiah Willcock