hi, here is the code fragment in my win32 project: namespace gtl { typedef unsigned int dword; }; void myFun( const char * _szText ){} int i = 10; myFun( boost::str( boost::format( " Page %2d" ) %i ).c_str() ); but there is so many more warinings as below: LobbyRoomListWnd.cpp d:\working\alan_gamma\publiclibrary\boost\boost\format\alt_sstream_impl.hpp(100) : warning C4244: '+=' : conversion from '__w64 int' to 'boost::io::basic_altstringbuf<Ch,Tr,Alloc>::off_type', possible loss of data with [ Ch=char, Tr=std::char_traits<char>, Alloc=std::allocator<char> ] c:\program files\microsoft visual studio .net 2003\vc7\include\xtree(267) : while compiling class-template member function 'boost::io::basic_altstringbuf<Ch,Tr,Alloc>::pos_type boost::io::basic_altstringbuf<Ch,Tr,Alloc>::seekoff (boost::io::basic_altstringbuf<Ch,Tr,Alloc>::off_type,std::_Iosb<_Dummy>::seekdir,std::_Iosb<_Dummy>::openmode)' with [ Ch=char, Tr=std::char_traits<char>, Alloc=std::allocator<char>, _Dummy=int ] d:\working\alan_gamma\publiclibrary\boost\boost\format\format_class.hpp(136) : see reference to class template instantiation 'boost::io::basic_altstringbuf<Ch,Tr,Alloc>' being compiled with [ Ch=char, Tr=std::char_traits<char>, Alloc=std::allocator<char> ] d:\working\alan_gamma\richonlineclient\roclient\game\lobby\lobbyroomlistwnd.cpp(427) : see reference to class template instantiation 'boost::basic_format<Ch>' being compiled with [ Ch=char ] d:\working\alan_gamma\publiclibrary\boost\boost\format\alt_sstream_impl.hpp(102) : warning C4244: '+=' : conversion from '__w64 int' to 'boost::io::basic_altstringbuf<Ch,Tr,Alloc>::off_type', possible loss of data with [ Ch=char, Tr=std::char_traits<char>, Alloc=std::allocator<char> ] d:\working\alan_gamma\publiclibrary\boost\boost\format\alt_sstream_impl.hpp(110) : warning C4244: 'argument' : conversion from '__w64 int' to 'int', possible loss of data d:\working\alan_gamma\publiclibrary\boost\boost\format\alt_sstream_impl.hpp(118) : warning C4244: '+=' : conversion from '__w64 int' to 'boost::io::basic_altstringbuf<Ch,Tr,Alloc>::off_type', possible loss of data with [ Ch=char, Tr=std::char_traits<char>, Alloc=std::allocator<char> ] d:\working\alan_gamma\publiclibrary\boost\boost\format\alt_sstream_impl.hpp(120) : warning C4244: '+=' : conversion from '__w64 int' to 'boost::io::basic_altstringbuf<Ch,Tr,Alloc>::off_type', possible loss of data with [ Ch=char, Tr=std::char_traits<char>, Alloc=std::allocator<char> ] d:\working\alan_gamma\publiclibrary\boost\boost\format\alt_sstream_impl.hpp(151) : warning C4244: 'argument' : conversion from '__w64 int' to 'int', possible loss of data c:\program files\microsoft visual studio .net 2003\vc7\include\xtree(267) : while compiling class-template member function 'boost::io::basic_altstringbuf<Ch,Tr,Alloc>::pos_type boost::io::basic_altstringbuf<Ch,Tr,Alloc>::seekpos (boost::io::basic_altstringbuf<Ch,Tr,Alloc>::pos_type,std::_Iosb<_Dummy>::openmode)' with [ Ch=char, Tr=std::char_traits<char>, Alloc=std::allocator<char>, _Dummy=int ] d:\working\alan_gamma\publiclibrary\boost\boost\format\alt_sstream_impl.hpp(160) : warning C4244: 'argument' : conversion from '__w64 long' to 'int', possible loss of data d:\working\alan_gamma\publiclibrary\boost\boost\format\alt_sstream_impl.hpp(265) : warning C4244: 'initializing' : conversion from '__w64 int' to 'int', possible loss of data c:\program files\microsoft visual studio .net 2003\vc7\include\xtree(267) : while compiling class-template member function 'boost::io::basic_altstringbuf<Ch,Tr,Alloc>::int_type boost::io::basic_altstringbuf<Ch,Tr,Alloc>::overflow (boost::io::basic_altstringbuf<Ch,Tr,Alloc>::int_type)' with [ Ch=char, Tr=std::char_traits<char>, Alloc=std::allocator<char> ] d:\working\alan_gamma\publiclibrary\boost\boost\format\alt_sstream_impl.hpp(266) : warning C4244: 'initializing' : conversion from '__w64 int' to 'int', possible loss of data d:\working\alan_gamma\publiclibrary\boost\boost\format\format_implementation.hpp(193) : warning C4267: 'initializing' : conversion from 'size_t' to 'std::streamsize', possible loss of data c:\program files\microsoft visual studio .net 2003\vc7\include\ios(119) : while compiling class-template member function 'boost::basic_format<Ch>::string_type boost::basic_format<Ch>::str(void) const' with [ Ch=char ] c:\program files\microsoft visual studio .net 2003\vc7\include\xtree(267) : while compiling class-template member function 'boost::basic_format<Ch>::basic_format(const Ch *)' with [ Ch=char ] d:\working\alan_gamma\publiclibrary\boost\boost\format\format_implementation.hpp(206) : warning C4267: 'initializing' : conversion from 'size_t' to 'std::streamsize', possible loss of data d:\working\alan_gamma\publiclibrary\boost\boost\optional\optional.hpp(102) : while compiling class-template member function 'boost::basic_format<Ch>::size_type boost::basic_format<Ch>::size(void) const' with [ Ch=char ] c:\program files\microsoft visual studio .net 2003\vc7\include\ios(119) : while compiling class-template member function 'boost::basic_format<Ch> &boost::basic_format<Ch>::parse(const boost::basic_format<Ch>::string_type &)' with [ Ch=char ] d:\working\alan_gamma\publiclibrary\boost\boost\format\format_implementation.hpp(210) : warning C4267: '+=' : conversion from 'size_t' to 'std::streamsize', possible loss of data d:\working\alan_gamma\publiclibrary\boost\boost\format\format_implementation.hpp(213) : warning C4267: '+=' : conversion from 'size_t' to 'std::streamsize', possible loss of data RichOnline.cpp c:\program files\microsoft visual studio .net 2003\vc7\include\xutility(1136) : warning C4267: '=' : conversion from 'size_t' to 'std::allocator<_Ty>::value_type', possible loss of data with [ _Ty=gtl::dword ] c:\program files\microsoft visual studio .net 2003\vc7\include\vector(862) : see reference to function template instantiation 'void std::fill<std::vector<_Ty>::_Tptr,_Ty>(_FwdIt,_FwdIt,const _Ty &)' being compiled with [ _Ty=size_t, _FwdIt=std::vector<size_t>::_Tptr ] c:\program files\microsoft visual studio .net 2003\vc7\include\vector(809) : while compiling class-template member function 'void std::vector<_Ty>::_Insert_n(std::vector<_Ty>::iterator,std::vector<_Ty>::size_type,const _Ty &)' with [ _Ty=size_t ] d:\working\alan_gamma\publiclibrary\boost\boost\regex\v4\cregex.hpp(229) : see reference to class template instantiation 'std::vector<_Ty>' being compiled with [ _Ty=size_t ] c:\program files\microsoft visual studio .net 2003\vc7\include\xutility(1161) : warning C4267: '=' : conversion from 'size_t' to 'std::allocator<_Ty>::value_type', possible loss of data with [ _Ty=gtl::dword ] c:\program files\microsoft visual studio .net 2003\vc7\include\memory(237) : see reference to function template instantiation 'void std::fill_n<_Ty*,_Diff,_Tval>(_OutIt,_Diff,const _Ty &)' being compiled with [ _Ty=std::allocator<gtl::dword>::value_type, _Diff=std::vector<size_t>::size_type, _Tval=size_t, _OutIt=std::allocator<gtl::dword>::value_type * ] c:\program files\microsoft visual studio .net 2003\vc7\include\memory(257) : see reference to function template instantiation 'void std::_Uninit_fill_n<std::allocator<_Ty>::value_type,_Diff,_Tval>(_Ty *,_Diff,const _Tval &,std::allocator<_Ty> &,std::_Scalar_ptr_iterator_tag)' being compiled with [ _Ty=gtl::dword, _Diff=std::vector<size_t>::size_type, _Tval=size_t ] c:\program files\microsoft visual studio .net 2003\vc7\include\vector(878) : see reference to function template instantiation 'void std::_Uninitialized_fill_n<std::vector<_Ty>::pointer,std::vector<_Ty>::size_type,_Ty,std::_Vector_val<_Ty,_Alloc>::_Alty>(_FwdIt,_Diff,const _Tval &,_Alloc &)' being compiled with [ _Ty=size_t, _Alloc=std::allocator<gtl::dword>, _FwdIt=std::vector<size_t>::pointer, _Diff=std::vector<size_t>::size_type, _Tval=size_t ] c:\program files\microsoft visual studio .net 2003\vc7\include\vector(877) : while compiling class-template member function 'std::vector<_Ty>::pointer std::vector<_Ty>::_Ufill(std::vector<_Ty>::pointer,std::vector<_Ty>::size_type,const _Ty &)' with [ _Ty=size_t ] thanks very much for any reply. -- Yours Sincerely, Alan Huang