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[Solved] dll import problem
I'm trying to add a library to my project.
In .pro I ve already add the library:
@LIBS += -L$$PWD\libs\Vicon\ -lViconDataStreamSDK_CPP
INCLUDEPATH += $$PWD\libs\Vicon\include@
In .cpp already add the header file:
This header has a lot of classes inside of a namespace which i called:
@using namespace ViconDataStreamSDK::CPP;@
Everything seems ok, I call the classes, but when debugging an error occur with dll import:
engine.obj:-1: error: LNK2019: unresolved external symbol "__declspec(dllimport) public: class ViconDataStreamSDK::CPP::Output_Connect __thiscall ViconDataStreamSDK::CPP::Client::Connect(class ViconDataStreamSDK::CPP::String const &)" (_imp?Connect@Client@CPP@ViconDataStreamSDK@@QAE?AVOutput_Connect@23@ABVString@23@@Z) referenced in function "public: void __thiscall Engine::ConnectVicon(void)" (?ConnectVicon@Engine@@QAEXXZ)
engine.obj:-1: error: LNK2019: unresolved external symbol "__declspec(dllimport) public: __thiscall ViconDataStreamSDK::CPP::Client::Client(void)" (_imp??0Client@CPP@ViconDataStreamSDK@@QAE@XZ) referenced in function "public: void __thiscall Engine::ConnectVicon(void)" (?ConnectVicon@Engine@@QAEXXZ)
It seems is connected with this part of my header file Client.h:
#define CLASS_DECLSPEC __declspec(dllexport)
#define CLASS_DECLSPEC __declspec(dllimport)
#endif // _EXPORTING@
And I have .dll and the .lib files inside the correct folders.....
Any ideia whats going on?
Are you sure the library is properly named? ViconDataStreamSDK_CPP.lib?
Yes.... can deceive because the CPP but both of them are in the folder of debugging and in the folder of the .pro path
ViconDataStreamSDK_CPP -> Object File Library
Could it be because they were made with Visual Studio C++ and Im using Qt IDE? Any conflict?
Are you sure this lib and dll were built with Visual Studio? Not MinGW/Cygwin and therefore GCC as a compiler?
Not sure, but in the Software Development Kit they just say this:
Windows – C++
Your application should
Link against “ViconDataStreamSDK_CPP.lib”
“Microsoft.VC8.CRT” (x86) or “Microsoft.VC9.CRT” (x64).
And I've put both the dlls in the correct folders.
Well then you have a "mangling":http://en.wikipedia.org/wiki/Name_mangling problem: your DLL was built against an older version of Visual Studio which exported the symbols for C++ in a different way.
You will only be able to link against that DLL with code compiled using:
Visual Studio 2005 aka VC80 for the 32 bits version
Visual Studio 2008 aka VC90 for the 64 bits version
If you use a newer version of Visual Studio, then you will have to get newer versions of that library.
Enjoy the joys of programming on the Windows platform :D
Problem was solved.
With new dll, the problem was solved.
Thank you all
marcanudo last edited by
Have the same problem, sent you a pm JLamas.