C++ Project compiles as static lib, fails (linker error) as dynamic lib. why?

Question

I've a VS2008 native C++ project, that I wish to compile as a DLL.

It only references one external library (log4cplus.lib), and uses its functions. (also uses log4cplus's .h files , naturally).

When I try to compile my project as a static library, it succeeeds. When I try as DLL, it fails :

1>MessageWriter.obj : error LNK2019: unresolved external symbol "public: static class log4cplus::Logger __cdecl log4cplus::Logger::getInstance(class std::basic_string<wchar_t,struct std::char_traits<wchar_t>,class std::allocator<wchar_t> > const &)" (?getInstance@Logger@log4cplus@@SA?AV12@ABV?$basic_string@_WU?$char_traits@_W@std@@V?$allocator@_W@2@@std@@@Z) referenced in function "class log4cplus::Logger __cdecl Log(void)" (?Log@@YA?AVLogger@log4cplus@@XZ)

There are 4 more errors just like this related to functions within log4cplus.lib.

It seems like something really stupid.. please help me :)

Thanks!

Edit :

I am linked against the log4cplus.lib file, and it finds it just fine. also, the log4cplus.lib is 100% functional, I am using it in another project with no problems. My original intention was to compile my project as a static library and use it in another DLL I am writing, but when do this, I get the same linker errors in that other project...

Edit #2 :

The functions which cause the linker errors are static functions.. could this be part of the problem?

Answer 1

wilx is right.I have the same link problem.

it took me almost one day to slove this issue.

I have downloaded log4cplus-1.0.4, after I opened this project with visual studio 2010,compile it, both static and dynamic library, no error.

however, when I try to use those library, I got a link error,no matter static library or dynamic library.

the reason is,by default, those project use multi-byte character, however, my own project use unicode,so,to slove those link problem, you just need to change one project's charset.

both unicode or both multi-byte charset.

and to change one project's charset in visual studio 2010, see the following link.

How do I turn off Unicode in a VC++ project?