Hello, I attach a diff for parsers.cpp which avoids error in my previous message, but now linker claims :( bin\boost\libs\program_options\build\libboost_program_options.lib\mingw\debu g\threading-multi\libboost_program_options-mgw-mt-d-1_31.lib(convert.obj)(.r data$_ZTVSt7codecvtIwciE+0x10): In function `ZNSbIwSt11char_traitsIwESaIwEE13_S_copy_charsEPwS3_S3_': C:/CPP/MINGW/include/c++/3.3.1/bits/stl_iterator_base_funcs.h: undefined reference to `std::codecvt<wchar_t, char, int>::do_out(int&, wchar_t const*, wchar_t const*, wchar_t const*&, char*, char*, char*&) const' bin\boost\libs\program_options\build\libboost_program_options.lib\mingw\debu g\threading-multi\libboost_program_options-mgw-mt-d-1_31.lib(convert.obj)(.r data$_ZTVSt7codecvtIwciE+0x14):C:/CPP/MINGW/include/c++/3.3.1/bits/stl_itera tor_base_funcs.h: undefined reference to `std::codecvt<wchar_t, char, int>::do_unshift(int&, char*, char*, char*&) const' bin\boost\libs\program_options\build\libboost_program_options.lib\mingw\debu g\threading-multi\libboost_program_options-mgw-mt-d-1_31.lib(convert.obj)(.r data$_ZTVSt7codecvtIwciE+0x18):C:/CPP/MINGW/include/c++/3.3.1/bits/stl_itera tor_base_funcs.h: undefined reference to `std::codecvt<wchar_t, char, int>::do_in(int&, char const*, char const*, char const*&, wchar_t*, wchar_t*, wchar_t*&) const' bin\boost\libs\program_options\build\libboost_program_options.lib\mingw\debu g\threading-multi\libboost_program_options-mgw-mt-d-1_31.lib(convert.obj)(.r data$_ZTVSt7codecvtIwciE+0x1c):C:/CPP/MINGW/include/c++/3.3.1/bits/stl_itera tor_base_funcs.h: undefined reference to `std::codecvt<wchar_t, char, int>::do_encoding() const' bin\boost\libs\program_options\build\libboost_program_options.lib\mingw\debu g\threading-multi\libboost_program_options-mgw-mt-d-1_31.lib(convert.obj)(.r data$_ZTVSt7codecvtIwciE+0x20):C:/CPP/MINGW/include/c++/3.3.1/bits/stl_itera tor_base_funcs.h: undefined reference to `std::codecvt<wchar_t, char, int>::do_always_noconv() const' bin\boost\libs\program_options\build\libboost_program_options.lib\mingw\debu g\threading-multi\libboost_program_options-mgw-mt-d-1_31.lib(convert.obj)(.r data$_ZTVSt7codecvtIwciE+0x24):C:/CPP/MINGW/include/c++/3.3.1/bits/stl_itera tor_base_funcs.h: undefined reference to `std::codecvt<wchar_t, char, int>::do_length(int const&, char const*, char const*, unsigned) const' bin\boost\libs\program_options\build\libboost_program_options.lib\mingw\debu g\threading-multi\libboost_program_options-mgw-mt-d-1_31.lib(convert.obj)(.r data$_ZTVSt7codecvtIwciE+0x28):C:/CPP/MINGW/include/c++/3.3.1/bits/stl_itera tor_base_funcs.h: undefined reference to `std::codecvt<wchar_t, char, int>::do_max_length() const' Regards, Janusz