[Solved] dll import problem

JLamas

Hi.

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:
@#include "Client.h"@

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:

@#ifdef _EXPORTING
#define CLASS_DECLSPEC __declspec(dllexport)
#else
#define CLASS_DECLSPEC __declspec(dllimport)
#endif // _EXPORTING@

And I have .dll and the .lib files inside the correct folders.....
Any ideia whats going on?

Thank you.

rcari

Are you sure the library is properly named? ViconDataStreamSDK_CPP.lib?

JLamas

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.dll
and
ViconDataStreamSDK_CPP -> Object File Library

Could it be because they were made with Visual Studio C++ and Im using Qt IDE? Any conflict?

rcari

Are you sure this lib and dll were built with Visual Studio? Not MinGW/Cygwin and therefore GCC as a compiler?

JLamas

Not sure, but in the Software Development Kit they just say this:

Windows – C++
Your application should
#include “Client.h”
Link against “ViconDataStreamSDK_CPP.lib”
Redistribute:
“ViconDataStreamSDK_CPP.dll”
“Microsoft.VC8.CRT” (x86) or “Microsoft.VC9.CRT” (x64).

And I've put both the dlls in the correct folders.

rcari

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

JLamas

Problem was solved.

With new dll, the problem was solved.

Thank you all

marcanudo

Have the same problem, sent you a pm JLamas.