Re: Graph - return edge_descriptor (side-note)

From: richardshaw11 (richard.shaw_at_[hidden])
Date: 2002-08-23 01:12:11

I did mean to mention the compiler etc. It is -

gcc version 2.95.3-5 (cygwin special)

and boost 1.28

I did think after reading the graph introductin that the edge() 
function may do what I wanted but I couldn't find any other mention 
of it. Just discovered the adjacency_list_io classes after I'd spend 
the time writing my own (low tech ones).

I'll try using edge instead and see what happens

Thanks - it's great to get such a quick response.

--- In Boost-Users_at_y..., Tarjei Knapstad <tarjeik_at_c...> wrote:
> On Thu, 2002-08-22 at 10:19, Shaw, Richard A wrote:
> > Can anybody tell my why the find_edge function in the code below 
fails to
> > get a property if I return the first edge in the list.
> > 
> > This is what happens -
> > 
> > Find_edge looks for edge A - B
> > It winds it and prints out the edge descriptor, and the weight of 
the edge
> > It the returns the edge
> > The main code prints out the edge descriptor and the fails when 
trying to
> > print the weight.
> > 
> > BTW - Is there a ready made function to find an edge based on the 
vertices ?
> > 
> > #include <boost/config.hpp>
> > #include <iostream>
> > #include <fstream>
> > 
> > #include <boost/graph/graph_traits.hpp>
> > #include <boost/graph/adjacency_list.hpp>
> > #include <boost/graph/dijkstra_shortest_paths.hpp>
> > 
> > using namespace boost;
> > 
> > // Find edge
> > template <class Graph>
> > std::pair<bool, graph_traits<Graph>::edge_descriptor>
> > find_edge(graph_traits<Graph>::vertex_descriptor u,
> > graph_traits<Graph>::vertex_descriptor v,
> > 	Graph g)
> 
> It's a lot more efficient to pass a const reference to 
> the graph you're searching in.
> 
> As Jeremy though, I cannot reproduce your problem using gcc 3.1 and
> either of boost 1.2.8 or the latest CVS source tree.
> 
> Regards,
> Tarjei