CODEWITHSUNDEEP
c++listboostvectorboost-graph
Matteo Ceccarello
Matteo Ceccarello

Reputation: 231

Boost Graph Library: std::list as VertexList template parameter

I'm trying to build a graph with vertices stored in a std::list instead of a std::vector.

However I am confused by a compilation error I get. The minimal code I'm using is

#include <boost/graph/adjacency_list.hpp>

using namespace boost;

int main() {

  typedef adjacency_list< listS,listS > Graph;

  Graph g;

  add_edge(0,1,g);

  return 0;
}

Compiling with gcc-4.7.3 I get the following error:

/Users/matteo/Documents/workspace/graph-gravity-dec/src/test.cpp: In function 'int main()':
/Users/matteo/Documents/workspace/graph-gravity-dec/src/test.cpp:12:17: error: invalid conversion from 'int' to 'boost::detail::adj_list_gen<boost::adjacency_list<boost::listS, boost::listS>, boost::listS, boost::listS, boost::directedS, boost::no_property, boost::no_property, boost::no_property, boost::listS>::config::vertex_descriptor {aka void*}' [-fpermissive]
In file included from /opt/local/include/boost/graph/adjacency_list.hpp:246:0,
             from /Users/matteo/Documents/workspace/graph-gravity-dec/src/test.cpp:2:
/opt/local/include/boost/graph/detail/adjacency_list.hpp:681:5: error:   initializing argument 2 of 'std::pair<typename Config::edge_descriptor, bool> boost::add_edge(typename Config::vertex_descriptor, typename Config::vertex_descriptor, boost::directed_graph_helper<Config>&) [with Config = boost::detail::adj_list_gen<boost::adjacency_list<boost::listS, boost::listS>, boost::listS, boost::listS, boost::directedS, boost::no_property, boost::no_property, boost::no_property, boost::listS>::config; typename Config::edge_descriptor = boost::detail::edge_desc_impl<boost::directed_tag, void*>; typename Config::vertex_descriptor = void*]' [-fpermissive]

that seems complaining about an invalid conversion from int to void*.

However if I change listS to vecS everything works fine

#include <boost/graph/adjacency_list.hpp>

using namespace boost;

int main() {

  typedef adjacency_list< listS, vecS > Graph;

  Graph g;

  add_edge(0,1,g);

  return 0;
}

What am I missing? Isn't the container of vertices supposed to be interchangeable without further modification of the rest of the code?

Upvotes: 2

Views: 488

Answers (1)

doctorlove
doctorlove

Reputation: 19232

As people have said, you can't use 0, or 1 for a node in a list backed graph. This will work though:

typedef adjacency_list< listS,listS > Graph;
Graph g;
typedef boost::graph_traits < Graph >::vertex_descriptor Vertex;
Vertex v0 = boost::add_vertex(g);
Vertex v1 = boost::add_vertex(g);
boost::add_edge(v0, v1, g);

You need to make a vertex to add. There are some helpful bits of code in this question

Upvotes: 4

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