diff --git a/demo/lgf_demo.cc b/demo/lgf_demo.cc
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--- /dev/null
+++ b/demo/lgf_demo.cc
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+/* -*- C++ -*-
+ *
+ * This file is a part of LEMON, a generic C++ optimization library
+ *
+ * Copyright (C) 2003-2008
+ * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
+ * (Egervary Research Group on Combinatorial Optimization, EGRES).
+ *
+ * Permission to use, modify and distribute this software is granted
+ * provided that this copyright notice appears in all copies. For
+ * precise terms see the accompanying LICENSE file.
+ *
+ * This software is provided "AS IS" with no warranty of any kind,
+ * express or implied, and with no claim as to its suitability for any
+ * purpose.
+ *
+ */
+
+///\ingroup demos
+///\file
+///\brief Demonstrating graph input and output
+///
+/// This simple demo program gives an example of how to read and write
+/// a graph and additional maps (on the nodes or the edges) from/to a
+/// stream. 
+///
+/// \include reader_writer_demo.cc
+
+#include <iostream>
+#include <lemon/smart_graph.h>
+#include <lemon/lgf_reader.h>
+#include <lemon/lgf_writer.h>
+#include <lemon/random.h>
+
+
+using namespace lemon;
+
+int main(int argc, const char *argv[]) {
+  const int n = argc > 1 ? std::atoi(argv[1]) : 20;
+  const int e = argc > 2 ? std::atoi(argv[2]) : static_cast<int>(n * log(n));
+  const int m = argc > 3 ? std::atoi(argv[3]) : 100;
+
+  SmartDigraph digraph;
+
+  std::stringstream ss;
+
+  try {
+
+    typedef SmartDigraph Digraph;
+    typedef Digraph::Node Node;
+    typedef Digraph::Arc Arc;
+    typedef Digraph::ArcIt ArcIt;
+
+    typedef Digraph::NodeMap<int> PotentialMap;
+    typedef Digraph::ArcMap<int> CapacityMap;
+    typedef Digraph::ArcMap<std::string> NameMap;
+
+    Digraph digraph;
+    PotentialMap potential(digraph);
+    CapacityMap capacity(digraph);
+    NameMap name(digraph);
+
+    std::vector<Node> nodes;
+    for (int i = 0; i < n; ++i) {
+      Node node = digraph.addNode();
+      potential[node] = rnd[m];
+      nodes.push_back(node);
+    }
+
+    std::vector<Arc> arcs;
+    for (int i = 0; i < e; ++i) {
+      int s = rnd[n];
+      int t = rnd[n];
+      int c = rnd[m];
+      Arc arc = digraph.addArc(nodes[s], nodes[t]);
+      capacity[arc] = c;
+      std::ostringstream os;
+      os << "arc \t" << i << std::endl;
+      name[arc] = os.str();
+      arcs.push_back(arc);
+    }
+
+
+    DigraphWriter<Digraph>(ss, digraph).
+      nodeMap("potential", potential).
+      arcMap("capacity", capacity).
+      arcMap("name", name).
+      node("source", nodes[0]).
+      node("target", nodes[1]).
+      arc("bottleneck", arcs[e / 2]).
+      attribute("creator", "lemon library").
+      run();
+
+  } catch (DataFormatError& error) {
+    std::cerr << error.what() << std::endl;
+  }
+
+  try {
+
+    typedef SmartDigraph Digraph;
+    typedef Digraph::Node Node;
+    typedef Digraph::Arc Arc;
+    typedef Digraph::ArcIt ArcIt;
+
+    typedef Digraph::NodeMap<int> LabelMap;
+    typedef Digraph::NodeMap<int> PotentialMap;
+    typedef Digraph::ArcMap<int> CapacityMap;
+    typedef Digraph::ArcMap<std::string> NameMap;
+
+    Digraph digraph;
+    LabelMap label(digraph);
+    PotentialMap potential(digraph);
+    CapacityMap capacity(digraph);
+    NameMap name(digraph);
+
+    Node s, t;
+    Arc a;
+    
+    std::string creator;
+
+    for (int i = 0; i < n; ++i) {
+      Node node = digraph.addNode();
+      label[node] = i;
+    }
+    
+    DigraphReader<Digraph>(ss, digraph).
+      useNodes(label).
+      nodeMap("potential", potential).
+      arcMap("capacity", capacity).
+      arcMap("name", name).
+      node("source", s).
+      node("target", t).
+      arc("bottleneck", a).
+      attribute("creator", creator).
+      run();
+
+    DigraphWriter<Digraph>(std::cout, digraph).
+      nodeMap("potential", potential).
+      arcMap("capacity", capacity).
+      arcMap("name", name).
+      node("source", s).
+      node("target", t).
+      arc("bottleneck", a).
+      attribute("creator", creator).
+      run();
+
+  } catch (DataFormatError& error) {
+    std::cerr << error.what() << std::endl;
+  }
+
+
+  return 0;
+}