Boost_1_39_0/libs/graph/example/default-constructor.cpp

   1 //=======================================================================
   2 // Copyright 2001 Jeremy G. Siek, Andrew Lumsdaine, Lie-Quan Lee,
   3 //
   4 // Distributed under the Boost Software License, Version 1.0. (See
   5 // accompanying file LICENSE_1_0.txt or copy at
   6 // http://www.boost.org/LICENSE_1_0.txt)
   7 //=======================================================================
   8 #include <boost/config.hpp>
   9 #include <fstream>
  10 #include <boost/graph/adjacency_list.hpp>
  11
  12 using namespace boost;
  13
  14 template < typename Graph > void
  15 read_graph_file(std::istream & in, Graph & g)
  16 {
  17   typedef typename graph_traits < Graph >::vertices_size_type size_type;
  18   size_type n_vertices;
  19   in >> n_vertices;             // read in number of vertices
  20   for (size_type i = 0; i < n_vertices; ++i)    // Add n vertices to the graph
  21     add_vertex(g);
  22   size_type u, v;
  23   while (in >> u)               // Read in pairs of integers as edges
  24     if (in >> v)
  25       add_edge(u, v, g);
  26     else
  27       break;
  28 }
  29
  30
  31 int
  32 main()
  33 {
  34   typedef adjacency_list < listS,       // Store out-edges of each vertex in a std::list
  35     vecS,                       // Store vertex set in a std::vector
  36     directedS                   // The graph is directed
  37   > graph_type;
  38
  39   graph_type g;                 // use default constructor to create empty graph
  40   std::ifstream file_in("makefile-dependencies.dat");
  41   read_graph_file(file_in, g);
  42
  43   assert(num_vertices(g) == 15);
  44   assert(num_edges(g) == 19);
  45   return 0;
  46 }