QtCreator LNK2019 error with external library - c++

Question

I have a problem when I want to link a library to my Qt project.
When I try to include an external library (libnodave.lib) in Qt Creator and try to build it, the following error occurs.
main.obj:-1: Fehler: LNK2019: unresolved external symbol __imp_daveSetDebug referenced in function main
I'm pretty sure that I included all needed files in my project and the .pro file. I used the "Add Library" wizard to add the library.
After no success with Qt Creator, I created a minimal example with Visual Studio. When I include all the needed files to the VS project, I can build and run it without errors. So I think that there must be a problem with Qt Creator linking the library. I also tried the Qt-Visual-Studio-Add-in, but there, the same error occurs.
Here are my minimal examples with the library I want to include.
In the Visual Studio example, I added the library path, the include path, and the name of the library to the project properties. It works.
I hope you can help me with my problem.
EDIT:
I want to use the library to get some data from a S7-300 SPS device.
The following code is the minimal example from Qt Creator.
#include <QCoreApplication>
#include <QDebug>
#include <nodave.h>
int main(int argc, char *argv[])
{
QCoreApplication a(argc, argv);
daveInterface *di;
daveSetDebug(daveDebugConnect); // Function of libnodave Library
qDebug() << "Hello World";
return a.exec();
}
This is the whole code from the Visual Studio minimal example.
#include "stdafx.h"
#include <nodave.h>
int _tmain(int argc, _TCHAR* argv[])
{
daveInterface *di;
daveSetDebug(daveDebugConnect);
printf("Hello World\n");
return 0;
}
The code is very small, so I don't think that there is an error inside.
That's why I think it must be a problem with the Qt linker or something like that.
EDIT:
My .pro file.
QT += core
QT -= gui
TARGET = qtminimal
CONFIG += console
CONFIG -= app_bundle
TEMPLATE = app
SOURCES += main.cpp
win32: LIBS += -L$$PWD/../libnodave-0.8.5/win/ -llibnodave
INCLUDEPATH += $$PWD/../libnodave-0.8.5
DEPENDPATH += $$PWD/../libnodave-0.8.5

Answer 1

The problem was that the Qt project is 64bit and the library I want to include is only 32bit.
So I downloaded the 32bit version of Qt and now it works.
I found the mistake, when I tried to build only the minimal example with libnodave, without any 64bit Qt libraries.
By creating a new Qt project in VS2013, with this workaround and adding the libnodave library afterwards I could change whether it should be a 64bit or 32bit build. By choosing the 32bit build, the Qt library creates errors but not the libnodave lib. When I choose 64bit build, only libnodave creates the errors.
I hope it is useful for someone else.