I’m having trouble reading a GraphML file using the Boost Graph Library. The file is created without issues, but reading it back throws a parse error. Here’s a summary of what I’m doing:

1. I Create my example of graph and I save it using write_graphml. This graph only has an unique Vertex Property and no Edge properties. The code used to do so is:

   ... variables ...
   
   typedef boost::property<boost::vertex_name_t, std::string> Node_name;
   typedef boost::adjacency_list<boost::vecS, boost::vecS, boost::directedS, Node_name> Graph;
   typedef boost::graph_traits<Graph>::vertex_descriptor Vertex;
   typedef std::unordered_map<std::string, Vertex> VertexMap;
   
   Graph g;
   VertexMap vertex_map;
   
   
   ... build the graph ...
   
   std::string name = "../tmp/" + analyzed_file + ".graphml";
   std::ofstream graph_ML(name);
   boost::dynamic_properties dp;
   dp.property("name", boost::get(boost::vertex_name, g));
   
   boost::write_graphml(graph_ML, g, dp);
   

   This code works perfectly. My file is properly saved in the desired directory.

2. However, when I try to read it with the following code:

   std::string graph_ml_file_name = "../tmp/" + analyzed_file + ".graphml";
   std::ifstream graphml_file(graph_ml_file_name);
   
   if(!graphml_file)
   {
      std::cerr << "Error opening the file" << std::endl;
      return -1;
   }
   
   boost::dynamic_properties dp;
   dp.property("name", boost::get(boost::vertex_name, g));
   
   try
   {
      boost::read_graphml(graphml_file,g,dp);
   }
   catch(const std::exception& e)
   {
      std::cerr << "Error opening the graphml file" << e.what() << std::endl;
      return -1;
   }
   

   I receive the error: Error opening the graphml file: parse error: unrecognized type “

I’ve looked through the documentation and couldn’t find specifics about handling this error. Has anyone faced this issue or can suggest what might be going wrong?

I have been researching similar errors online as well as reading the official Boost Graph documentation, but I have not found a solution.