Difference between revisions of "Boost/BGL/Directed/Weighted"

#include <iostream>
#include <boost/graph/graph_traits.hpp>
#include <boost/graph/directed_graph.hpp>
 
typedef boost::property<boost::edge_weight_t, float> EdgeWeightProperty;
 
typedef boost::directed_graph<boost::no_property, EdgeWeightProperty> Graph;
 
int main(int,char*[])
{
  // Create a graph object
  Graph g;
 
  // Add vertices to the graph
  Graph::vertex_descriptor v0 = g.add_vertex();
  Graph::vertex_descriptor v1 = g.add_vertex();
  Graph::vertex_descriptor v2 = g.add_vertex();
 
  // Create weighted edges
  EdgeWeightProperty weight0 = 5;
  boost::add_edge(v0,v1,weight0,g);
 
  EdgeWeightProperty weight1 = 6;
  boost::add_edge(v1,v2,weight1,g);
 
  // Retrieve the weight of an edge (method 1, works)
  {
  typedef boost::property_map<Graph, boost::edge_weight_t>::type EdgeWeightMap;
  EdgeWeightMap edgeWeightMap = get(boost::edge_weight, g);
 
  std::pair<Graph::edge_descriptor, bool> edgePair = boost::edge(v0, v1, g);
  Graph::edge_descriptor edge = edgePair.first;
 
  std::cout << "Edge (" << v0 << ", " << v1 << ") has weight " << edgeWeightMap[edge] << std::endl;
  }
 
  // Retrieve the weight of an edge (method 2, doesn't work)
  {
  std::pair<Graph::edge_descriptor, bool> edgePair = boost::edge(v0, v1, g);
  Graph::edge_descriptor edge = edgePair.first;
  std::cout << "Edge (" << v0 << ", " << v1 << ") has weight " << g[edge]->edge_weight << std::endl;
  }
 
  return 0;
}