I've owned the BGL book for a few years and am, just now, having a go at chapter 3. I've written... #include int main() { return EXIT_SUCCESS; } ...and, when I compile it using vc9, get... Compiling... main.cpp c:\boost_1_42_0\boost\unordered\unordered_set.hpp(402) : error C2220: warning treated as error - no 'object' file generated c:\boost_1_42_0\boost\unordered\unordered_set.hpp(500) : see reference to class template instantiation 'boost::unordered_set' being compiled c:\boost_1_42_0\boost\unordered\unordered_set.hpp(402) : warning C4224: nonstandard extension used : formal parameter 'hash' was previously defined as a type c:\boost_1_42_0\boost\unordered\unordered_set.hpp(890) : warning C4224: nonstandard extension used : formal parameter 'hash' was previously defined as a type c:\boost_1_42_0\boost\unordered\unordered_set.hpp(989) : see reference to class template instantiation 'boost::unordered_multiset' being compiled c:\boost_1_42_0\boost\multi_index\detail\bucket_array.hpp(115) : warning C4224: nonstandard extension used : formal parameter 'hash' was previously defined as a type c:\boost_1_42_0\boost\multi_index\detail\bucket_array.hpp(165) : see reference to class template instantiation 'boost::multi_index::detail::bucket_array<Allocator>' being compiled c:\boost_1_42_0\boost\multi_index\hashed_index.hpp(437) : warning C4224: nonstandard extension used : formal parameter 'hash' was previously defined as a type c:\boost_1_42_0\boost\multi_index\hashed_index.hpp(1170) : see reference to class template instantiation 'boost::multi_index::detail::hashed_index' being compiled c:\boost_1_42_0\boost\multi_index\hashed_index.hpp(462) : warning C4224: nonstandard extension used : formal parameter 'hash' was previously defined as a type c:\boost_1_42_0\boost\multi_index\hashed_index.hpp(492) : warning C4224: nonstandard extension used : formal parameter 'hash' was previously defined as a type c:\boost_1_42_0\boost\graph\named_graph.hpp(304) : warning C4224: nonstandard extension used : formal parameter 'property' was previously defined as a type c:\boost_1_42_0\boost\graph\named_graph.hpp(316) : see reference to class template instantiation 'boost::graph::named_graph' being compiled c:\boost_1_42_0\boost\graph\named_graph.hpp(309) : warning C4224: nonstandard extension used : formal parameter 'property' was previously defined as a type c:\boost_1_42_0\boost\graph\named_graph.hpp(360) : warning C4224: nonstandard extension used : formal parameter 'property' was previously defined as a type c:\boost_1_42_0\boost\graph\named_graph.hpp(368) : warning C4224: nonstandard extension used : formal parameter 'property' was previously defined as a type Build log was saved at "file://c:\sigmaTrunk\boost\vc\Debug\BuildLog.htm" boost - 1 error(s), 10 warning(s) ========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ========== ...is this to be expected? BTW, very much liked chapter 2, best in the book. Louis.