I'm trying to use an external DLL (provided by AutoItX) with Visual C++ 2010. AutoItX provides a DLL, but for some reason not a LIB, so I generated one with Visual Studio.
The problem is that the linker seems to have trouble linking against the library. I added AutoItX3.lib as an additional dependency under Properties->Linker -> Inputs, and added the directory to Properties -> Linker -> General -> Additional Library Directories. No matter what I do, I still get these errors:
1>main.obj : error LNK2019: unresolved external symbol _AU3_Send#8 referenced in function _WinMain#16
1>main.obj : error LNK2019: unresolved external symbol _AU3_WinWaitActive#12 referenced in function _WinMain#16
1>main.obj : error LNK2019: unresolved external symbol _AU3_Run#12 referenced in function _WinMain#16
1>main.obj : error LNK2019: unresolved external symbol _AU3_Sleep#4 referenced in function _WinMain#16
AU3_Send, AU3_WinWaitActive, AU3_Run, and AU3_Sleep are functions called by the program, main.cpp. I'm really out of ideas, because these functions clearly exist in the DLL. Any help would be appreciated.
It is very common to provide only DLLs as a mean of interfaces. Many software providers do that. Doing this has following impacts (consequences):
the client applications can only dynamically link to the library provided (hence the name Dynamic-Link Library). The binding between the provider (the library) and the consumer (the App or any other Library) is made dynamically.
the client must use LoadLibray and GetProcAddress in order to bind the library and retrieve the Symbols (functions) desired
the interface (contract) between the Library and the consumer should be documented via a Header file - see AutoIt3.h for example - (or any other documentation like a help file, ..)
No LIB is provided (since it is not needed), since the Linking takes place at runtime, not at compiler/linker time
To resolve your problem you just need to remove the static dependency (the LIB) you put in the Visual Studio configuration and set the dependency at runtime using LoadLibrary and GetProcAddress
Related
I would like to integrate Lua into my current C++ application I build with VisualStudio 2015 (x64 mode).
I grabbed a simple Lua wrapper from here, and the Lua binaries for windows x64 from here (the lua-5.1.5_Win32_dll14_lib.zip one).
Next, I added the include and library path to the project preferences. Works so far in the IDE. However, when I try to compile the code it throws 24 errors (like these first two):
1>LuaScript.obj : error LNK2019: unresolved external symbol "lua_close" referenced in function ""public: __cdecl LuaScript::~LuaScript(void)" (??1LuaScript##QEAA#XZ)".
1>LuaScript.obj : error LNK2019: unresolved external symbol "lua_gettop" referenced in function ""public: void __cdecl LuaScript::clean(void)" (?clean#LuaScript##QEAAXXZ)".
which tells me next to nothing. Seems that the linker is unable to find the library but the includes are working and the path to library is set, too. Any suggestions what I might have missed or should look into? Any hint would be appreciated!
I have the following linker error in one project of a Visual Studio 2013 solution:
error LNK2019: unresolved external symbol "__declspec(dllimport) public: static class std::locale::_Locimp * __cdecl std::locale::_Getgloballocale(void)" (__imp_?_Getgloballocale#locale#std##SAPEAV_Locimp#12#XZ) referenced in function "class std::ctype<char> const & __cdecl std::use_facet<class std::ctype<char> >(class std::locale const &)" (??$use_facet#V?$ctype#D#std###std##YAAEBV?$ctype#D#0#AEBVlocale#0##Z)
In all projects I linked the run-time library dynamically (/MD).
I considered the hints in the following posts:
C++ linker unresolved external symbols
What libraries do I
need to link my mixed-mode application to?
Boost -
Unresolved external symbols when compiling linking with /MT instead
of /MD
Link error 2001:unresolved external symbol
Linker errors between multiple projects in Visual C++
but was not able to solve this issue.
Actually, I am not even aware of where in the project _Getgloballocale is used. Maybe it would also help to know the lib in which _Getgloballocale is located.
The projects use the following libraries:
cURL
Protobuf
libboost_thread-vc120-mt-1_56.lib
libboost_system-vc120-mt-1_56.lib
libboost_python-vc120-mt-1_56.lib
libboost_filesystem-vc120-mt-1_56.lib
In all projects I linked the run-time library dynamically (/MD).
As others noted, verifying this might be less obvious than appears. For one, some of your libraries might drag in external dependencies that do rely on a mis-matching runtime.
Suggest you link with /VERBOSE on (in your EXE project, properties / linker / general / show progress), and search the output dump for MSVCR. You might catch a different version (msvcr100.lib) or a different configuration (msvcr120d.lib). Also try to search for LIBCMT - that is the library for static linking of the runtime. These typically appear as part of a /DEFAULTLIB linker directive, and you should be able to understand from the dump in which library context this directive is present.
You can also post here the verbose output (or the relevant snippets), and we can try to help interpret it.
I have created Regular DLLs Dynamically Linked to MFC.
in before build dll in dll project i used add another class. this class provide more method of constructor overloading.
Then I build dll successfully after i used this lib and dll file include project and then go to build and get linker error when using constructor overloading class
My Class Name: Object
Error 11 error LNK2001: unresolved external symbol "public: __thiscall AvinashiAMF::Object::~Object(void)" (??1Object#AvinashiAMF##QAE#XZ) BuleCappServiceUseDynamicDllDlg.obj
Error 10 error LNK2001: unresolved external symbol "public: __thiscall AvinashiAMF::Object::Object(enum AvinashiAMF::ObjectType,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >)" (??0Object#AvinashiAMF##QAE#W4ObjectType#1#V?$basic_string#DU?$char_traits#D#std##V?$allocator#D#2##std###Z) BuleCappServiceUseDynamicDllDlg.obj
Error 12 fatal error LNK1120: 2 unresolved externals D:\Test Aplications\Visual Studio 2008\Projects\BuleCappServiceUseDynamicDll\Release\BuleCappServiceUseDynamicDll.exe
You're probably not exporting your class. See here http://msdn.microsoft.com/en-us/library/81h27t8c.aspx
Also, a nice tool to check for this kind of issues is depends.exe, included with Visual Studio, which allows you to check for exported and imported symbols.
There are two significantly different dynamic link libraries: implicitly linked and explicitly linked.
In short, implicitly linked is linked at the compile time. You need an import library to link with(.lib), header file with functions prototypes and properly usage of the dllexport and dllexport or use .def file.
dllexport/dllexport are easier to use in this case. System takes care of loading libraries (DLLs).
Explicit linking is a runtime linking. You do not need any import library or headers. You need to know what is the function signature. You have to explicitly call LoadLibrary and GetProcAddress to call the function.
To see how to properly create macros for export/import create empty Win32 project select DLL and make sure the Export symbols check box is checked.
In the main header file you will see explanation how to use macros for import/export.
I have a project in which I need to link some DirectX libraries in windows 8. I cannot figure out where to find these symbols, if it's because of a mismatch between versions/runtimes or whatever somewhere or what the hell could be happening.
So I link with these libraries, under windows 8.1 (with cmake):
set(MY_LIBS
general dsound
general d3d9
general dxerr
general strmiids
general comctl32
general winmm
general pdh
general ComDlg32
general Gdi32
general User32
general Ole32
general oleaut32
general Msimg32
general opengl32
general glu32
general PowrProf
general strmbase)
As you can see I also include strmbase, which is the sample compiled for base classes from the windows sdk, that I compiled myself. But I still have these unresolved references:
error LNK2019: unresolved external symbol _DirectSoundCaptureEnumerateW#8 referenced in...
error LNK2019: unresolved external symbol _GetDeviceID#8 referenced in...
error LNK2001: unresolved external symbol _GetDeviceID#8
error LNK2019: unresolved external symbol _DirectSoundEnumerateW#8 referenced in...
LNK2019: unresolved external symbol _DirectSoundCaptureCreate8#12 referenced in function...
error LNK2019: unresolved external symbol _DirectSoundCreate#12 referenced in function...
Does anyone have any idea where to find these symbols and/or what to do to get it compiling.
The problem was that there was a precompiled library trying to find these symbols in a 64-bit library. But the precompiled library was expecting 32-bit symbols because the name mangling is different. The problem was gone when I linked against 32-bit libraries, even if my system is 64 bits.
I just tried to build Qt for WinCE7.0 using VS2008 after lots of code modification I successfully compiled main libraries.
While Compiling the QtScript library I received the following linker errors:
1>Linking...
1> Creating library ..\..\lib\QtScript4.lib and object ..\..\lib\QtScript4.exp
1>BytecodeGenerator.obj : error LNK2019: unresolved external symbol __imp__Inf referenced in function "public: static double __cdecl QTWTF::FloatHashTraits<double>::emptyValue(void)" (?emptyValue#?$FloatHashTraits#N#QTWTF##SANXZ)
1>Executable.obj : error LNK2001: unresolved external symbol __imp__Inf
1>MathObject.obj : error LNK2001: unresolved external symbol __imp__Inf
1>DateMath.obj : error LNK2019: unresolved external symbol __imp__Nan referenced in function "double __cdecl QTWTF::parseDateFromNullTerminatedCharacters(char const *,bool &,int &)" (?parseDateFromNullTerminatedCharacters#QTWTF##YANPBDAA_NAAH#Z)
1>JSValue.obj : error LNK2001: unresolved external symbol __imp__Nan
1>..\..\lib\QtScript4.dll : fatal error LNK1120: 2 unresolved externals
I have absolutely no idea which libraries I missed to link with!
Thanks
If you're using Windows, I'll assume you're building in MSVS. I often start projects WITHOUT default libs and if I happen to touch "out of reach" terriotry from another lib, I add what I need as I go along.
Fortunately, MSVS is great at helping me with this. Just turn VERBOSE compiling status and see what libs it's trying to access, then just add them:
right click the project, linker, show progress -> select VERBOSE
Another method is when I check MSDN for Microsoft functions and see the lib they are declared in and add it (since VERBOSE can be overkill on my poor output window). I don't know if Qt has a detailed reference documentation (also stating the libs) but it's worth a shot.
When all else fails, just add all libs Qt could possibly want (make sure IGNORE STANDARD LIBS is disabled) then check VERBOSE and only keep those in the list.
Assuming you have all the libraries in the project, another problem is mismatched dependencies (right click the solution, startup project -> select the one you need, [project dependencies -> map each dependency for the specified libs).
Also make sure when you import an extern the lib is defined in Linker->Input.
However, if you modified the source (either adding new functions/global or static vars or you modified function signatures), the unresolved external reference means a function/var definition has no associated body. Either implement one or add { } in the definition; so if that's the case, check the functions/vars from the error message.