Hi, I am using Windows XP, boost 1.38 and mingw 3.4.5 (Code::Blocks IDE). I cannot compile BOOST_CHECK_EQUAL_COLLECTIONS when using wstring. See below: #define CHECK_EQUAL_COLLECTIONS(L, R) \ BOOST_CHECK_EQUAL_COLLECTIONS((L).begin (), (L).end (), (R).begin (), (R).end ()) vector<string > v1; vector<wstring> v2; CHECK_EQUAL_COLLECTIONS(v1, v1); // this compiles fine. CHECK_EQUAL_COLLECTIONS(v2, v2); // this gives me the error listed below (at the end). Searching for a solution I've found this: http://lists.boost.org/boost-users/2005/09/13720.php And in fact, adding the code below solves it. namespace std { ostream& operator << (ostream& ostr, wstring const& str) { ostr << boost::lexical_cast<wstring>(str); return ostr; } } However this seems somewhat clumsy to me. I do not like the idea of doing a cast like this that obviously can fail if the wstring has a wide char that cannot be mapped to char properly. And it seems inappropriate to require the user to define such a thing. Is there a better way of solving this ? Can anything be done in the unit test framework itself to solve this in a better way ? I am a beginner with template metaprogramming so I ask the experts here to tell me if there is a better way or if that's the way it is and nothing can be done. Thank you for your attention ! Mauricio. c:\boost_1_38_0\boost\test\utils\wrap_stringstream.hpp||In function `boost::basic_wrap_stringstream<CharT>& boost::operator<<(boost::basic_wrap_stringstream<CharT>&, const T&) [with CharT = char, T = std::basic_string<wchar_t, std::char_traits<wchar_t>, std::allocator<wchar_t> >]':| c:\boost_1_38_0\boost\test\test_tools.hpp|641|instantiated from `boost::test_tools::predicate_result boost::test_tools::tt_detail::equal_coll_impl(Left, Left, Right, Right) [with Left = __gnu_cxx::__normal_iterator<std::wstring*, std::vector<std::wstring, std::allocator<std::wstring> > >, Right = __gnu_cxx::__normal_iterator<std::wstring*, std::vector<std::wstring, std::allocator<std::wstring> > >]'| C:\projects\cpplib\source\test\string_util_test.cpp|71|instantiated from here| c:\boost_1_38_0\boost\test\utils\wrap_stringstream.hpp|66|error: no match for 'operator<<' in '(+targ)->boost::basic_wrap_stringstream<CharT>::stream [with CharT = char]() << t'| C:\CodeBlocks\MinGW\bin\..\lib\gcc\mingw32\3.4.5\..\..\..\..\include\c++\3.4.5\bits\ostream.tcc|63|note: candidates are: std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(std::basic_ostream<_CharT, _Traits>&(*)(std::basic_ostream<_CharT, _Traits>&)) [with _CharT = char, _Traits = std::char_traits<char>]| C:\CodeBlocks\MinGW\bin\..\lib\gcc\mingw32\3.4.5\..\..\..\..\include\c++\3.4.5\bits\ostream.tcc|74|note: std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(std::basic_ios<_CharT, _Traits>&(*)(std::basic_ios<_CharT, _Traits>&)) [with _CharT = char, _Traits = std::char_traits<char>]| C:\CodeBlocks\MinGW\bin\..\lib\gcc\mingw32\3.4.5\..\..\..\..\include\c++\3.4.5\bits\ostream.tcc|86|note: std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(std::ios_base&(*)(std::ios_base&)) [with _CharT = char, _Traits = std::char_traits<char>]| C:\CodeBlocks\MinGW\bin\..\lib\gcc\mingw32\3.4.5\..\..\..\..\include\c++\3.4.5\bits\ostream.tcc|121|note: std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(long int) [with _CharT = char, _Traits = std::char_traits<char>]| C:\CodeBlocks\MinGW\bin\..\lib\gcc\mingw32\3.4.5\..\..\..\..\include\c++\3.4.5\bits\ostream.tcc|155|note: std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(long unsigned int) [with _CharT = char, _Traits = std::char_traits<char>]| C:\CodeBlocks\MinGW\bin\..\lib\gcc\mingw32\3.4.5\..\..\..\..\include\c++\3.4.5\bits\ostream.tcc|98|note: std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(bool) [with _CharT = char, _Traits = std::char_traits<char>]| C:\CodeBlocks\MinGW\bin\..\lib\gcc\mingw32\3.4.5\..\..\..\..\include\c++\3.4.5\ostream|178|note: std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(short int) [with _CharT = char, _Traits = std::char_traits<char>]| C:\CodeBlocks\MinGW\bin\..\lib\gcc\mingw32\3.4.5\..\..\..\..\include\c++\3.4.5\ostream|189|note: std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(short unsigned int) [with _CharT = char, _Traits = std::char_traits<char>]| C:\CodeBlocks\MinGW\bin\..\lib\gcc\mingw32\3.4.5\..\..\..\..\include\c++\3.4.5\ostream|193|note: std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(int) [with _CharT = char, _Traits = std::char_traits<char>]| C:\CodeBlocks\MinGW\bin\..\lib\gcc\mingw32\3.4.5\..\..\..\..\include\c++\3.4.5\ostream|204|note: std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(unsigned int) [with _CharT = char, _Traits = std::char_traits<char>]| C:\CodeBlocks\MinGW\bin\..\lib\gcc\mingw32\3.4.5\..\..\..\..\include\c++\3.4.5\bits\ostream.tcc|179|note: std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(long long int) [with _CharT = char, _Traits = std::char_traits<char>]| C:\CodeBlocks\MinGW\bin\..\lib\gcc\mingw32\3.4.5\..\..\..\..\include\c++\3.4.5\bits\ostream.tcc|214|note: std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(long long unsigned int) [with _CharT = char, _Traits = std::char_traits<char>]| C:\CodeBlocks\MinGW\bin\..\lib\gcc\mingw32\3.4.5\..\..\..\..\include\c++\3.4.5\bits\ostream.tcc|238|note: std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(double) [with _CharT = char, _Traits = std::char_traits<char>]| C:\CodeBlocks\MinGW\bin\..\lib\gcc\mingw32\3.4.5\..\..\..\..\include\c++\3.4.5\ostream|219|note: std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(float) [with _CharT = char, _Traits = std::char_traits<char>]| C:\CodeBlocks\MinGW\bin\..\lib\gcc\mingw32\3.4.5\..\..\..\..\include\c++\3.4.5\bits\ostream.tcc|261|note: std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(long double) [with _CharT = char, _Traits = std::char_traits<char>]| C:\CodeBlocks\MinGW\bin\..\lib\gcc\mingw32\3.4.5\..\..\..\..\include\c++\3.4.5\bits\ostream.tcc|284|note: std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(const void*) [with _CharT = char, _Traits = std::char_traits<char>]| C:\CodeBlocks\MinGW\bin\..\lib\gcc\mingw32\3.4.5\..\..\..\..\include\c++\3.4.5\bits\ostream.tcc|307|note: std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(std::basic_streambuf<_CharT, _Traits>*) [with _CharT = char, _Traits = std::char_traits<char>]| c:\boost_1_38_0\boost\test\utils\xml_printer.hpp|103|note: std::ostream& boost::unit_test::operator<<(const boost::unit_test::custom_printer<boost::unit_test::pcdata>&, boost::unit_test::const_string)| c:\boost_1_38_0\boost\test\utils\lazy_ostream.hpp|40|note: std::ostream& boost::unit_test::operator<<(std::ostream&, const boost::unit_test::lazy_ostream&)| ||=== Build finished: 1 errors, 0 warnings ===| -- Mauricio Gomes Pensar Digital 55-11-8319-9610 (Brazil - mobile)