Linking 3rd Party Library: Unresolved Externals

[WickedOne612]

I am encountering a problem with linking a library and include files from an SDK into my Qt program. I'm using Qt5.3 to create a program and then linking the .lib and including the include files via the .pro file. It seems like I am able to get the library to link, but the compiler complains that there is an undefined reference.

More specifically:

I created a test Qt GUI program that contains a folder in the build directory as follows:

• /3rdparty
• • include
• • • IBScanUltimate.h
• • • IBScanUltimateApi.h
• • • IBScanUltimateApi_defs.h
• • • IBScanUltimateApi_err.h
• • • LinuxPort.h
• • lib
• • • IBScanUltimate.lib

The project file for Qt, which includes the library linking, is as follows:

@INCLUDEPATH += "C:\Users\jcady_000\Documents\Git\whirl_auth\test_software\TestFingerprint\3rdparty\IBScanUltimate\include"
INCLUDEPATH += "C:\Users\jcady_000\Documents\Git\whirl_auth\test_software\TestFingerprint\3rdparty\IBScanUltimate\lib"
LIBS += -L"C:\Users\jcady_000\Documents\Git\whirl_auth\test_software\TestFingerprint\3rdparty\IBScanUltimate\lib" -l"IBScanUltimate"

TEMPLATE = app

QT += qml quick

SOURCES += main.cpp

RESOURCES += qml.qrc

Additional import path used to resolve QML modules in Qt Creator's code model

QML_IMPORT_PATH =

Default rules for deployment.

include(deployment.pri)@

The main.cpp file is as follows:

@#include <QGuiApplication>
#include <QQmlApplicationEngine>
#include <QDebug>
#include "IBScanUltimate.h"
#include "IBScanUltimateApi.h"
#include "IBScanUltimateApi_defs.h"
#include "IBScanUltimateApi_err.h"

int main(int argc, char *argv[])
{
QGuiApplication app(argc, argv);

QQmlApplicationEngine engine;

engine.load(QUrl(QStringLiteral("qrc:///main.qml")));

int *pDeviceCount = 0;
if (IBSU_GetDeviceCount(pDeviceCount) > 0)
{
    qDebug() << "Connnected";
}
else
{
    qDebug() << "Disconnected";
}
return app.exec();

}@

On compiling, the file is linked, but it throws the following error:

@C:\Users\jcady_000\Documents\Git\whirl_auth\test_software\TestFingerprint\main.cpp:-1: error: undefined reference to `IBSU_GetDeviceCount@4'
collect2.exe:-1: error: error: ld returned 1 exit status@

It seems that while the compiler can detect the header file references and link the library successfully, it cannot resolve the reference to the IBSU_GetDeviceCount (or any) function.

Anyone have any idea what's going on or how to solve it?

Thank you,
Jay

[WickedOne612]

I think the problem might be that they library was compiled using Windows. Does anyone know how I can compile the library for Windows but the application for something else?

[SGaist]

Hi,

What do you mean by "compile a library for Windows but the application for something else" ?

Where does that SDK come from ? Which compiler was used ?

[WickedOne612]

For anyone else having the same problem, I solved it.

The library was compiled for a 64-bit version of windows. I got the 32-bit version from the maker and compiled it with MinGW 32-bit and it worked properly.