diff --git a/demo/arg_parser_demo.cc b/demo/arg_parser_demo.cc
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--- /dev/null
+++ b/demo/arg_parser_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 Argument parser demo
+///
+/// This example shows how the argument parser can be used.
+///
+/// \include arg_parser_demo.cc
+
+#include <lemon/arg_parser.h>
+
+using namespace lemon;
+int main(int argc, const char **argv)
+{
+  ArgParser ap(argc,argv);
+  int i;
+  std::string s;
+  double d;
+  bool b,sil;
+  bool g1,g2,g3;
+  ap.refOption("n", "An integer input.", i, true)
+    .refOption("val", "A double input.", d)
+    .synonym("vals","val")
+    .refOption("name", "A string input.", s)
+    .refOption("f", "A switch.", b)
+    .refOption("nohelp", "", sil)
+    .refOption("gra","Choice A",g1)
+    .refOption("grb","Choice B",g2)
+    .refOption("grc","Choice C",g3)
+    .optionGroup("gr","gra")
+    .optionGroup("gr","grb")
+    .optionGroup("gr","grc")
+    .mandatoryGroup("gr")
+    .onlyOneGroup("gr")
+    .other("infile","The input file.")
+    .other("...");
+  
+  ap.parse();
+
+  std::cout << "Parameters of '" << ap.commandName() << "':\n";
+
+  if(ap.given("n")) std::cout << "  Value of -n: " << i << std::endl;
+  if(ap.given("val")) std::cout << "  Value of -val: " << d << std::endl;
+  if(ap.given("name")) std::cout << "  Value of -name: " << s << std::endl;
+  if(ap.given("f")) std::cout << "  -f is given\n";
+  if(ap.given("nohelp")) std::cout << "  Value of -nohelp: " << sil << std::endl;
+  if(ap.given("gra")) std::cout << "  -gra is given\n";
+  if(ap.given("grb")) std::cout << "  -grb is given\n";
+  if(ap.given("grc")) std::cout << "  -grc is given\n";
+                                     
+  switch(ap.files().size()) {
+  case 0:
+    std::cout << "  No file argument was given.\n";
+    break;
+  case 1:
+    std::cout << "  1 file argument was given. It is:\n";
+    break;
+  default:
+    std::cout << "  "
+	      << ap.files().size() << " file arguments were given. They are:\n";
+  }
+  for(unsigned int i=0;i<ap.files().size();++i)
+    std::cout << "    '" << ap.files()[i] << "'\n";
+  
+}