Undefined reference to 'vtable for myClass'

? Offline

I have this undefined reference to 'vtable for myClass' problem. Why is it so?

I have a header file myClass.h which contains a slot function

@
#ifndef MYCLASS_H
#define MYCLASS_H
#include <QObject>
#include "qdebug.h"

class myClass : public QObject
{
Q_OBJECT

public slots:
void cppSlot(int number);

};

#endif // MYCLASS_H
@

A cpp file myClass.cpp

@
#include "myclass.h"

void myClass::cppSlot(int number) {
qDebug() << "Called the C++ slot with" << number;
}
@

with main file main.cpp

@
#include <QtGui/QApplication>
#include "qmlapplicationviewer.h"
#include "QDeclarativeContext"
#include "myclass.h"

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

QmlApplicationViewer viewer;
myClass MyClass;
viewer.rootContext()->setContextProperty("myObject", &MyClass);
viewer.setOrientation(QmlApplicationViewer::ScreenOrientationAuto);
viewer.setMainQmlFile&#40;QLatin1String("qml/test1/main.qml"&#41;);
viewer.showExpanded();

return app.exec();

}
@

I have also spcific the header and cpp file in my .pro file.

@

Add more folders to ship with the application, here

folder_01.source = qml/test1
folder_01.target = qml
DEPLOYMENTFOLDERS = folder_01

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

QML_IMPORT_PATH =

symbian:TARGET.UID3 = 0xE6EDC966

Allow network access on Symbian

symbian:TARGET.CAPABILITY += NetworkServices

Define QMLJSDEBUGGER to allow debugging of QML in debug builds

(This might significantly increase build time)

DEFINES += QMLJSDEBUGGER

If your application uses the Qt Mobility libraries, uncomment

the following lines and add the respective components to the

MOBILITY variable.

CONFIG += mobility

MOBILITY +=

The .cpp file which was generated for your project. Feel free to hack it.

SOURCES += main.cpp
myclass.cpp

Please do not modify the following two lines. Required for deployment.

include(qmlapplicationviewer/qmlapplicationviewer.pri)
qtcAddDeployment()

HEADERS +=
myclass.h
@

koahnig

Hi,
it would be good to see the complete error message as well.

? Offline

Hi koahnig,

The error message is as follows:

@
debug/main.o: In function myClass': C:\Laptop\Dropbox\Qt\examples\test1-build-desktop/../test1//myclass.h:7: undefined reference to vtable for myClass'
debug/main.o: In function ~myClass': C:\Laptop\Dropbox\Qt\examples\test1-build-desktop/../test1//myclass.h:7: undefined reference to vtable for myClass'
collect2: ld returned 1 exit status
mingw32-make[1]: *** [debug\test1.exe] Error 1
mingw32-make: *** [debug] Error 2
The process "C:\QtSDK\mingw\bin\mingw32-make.exe" exited with code 2.
Error while building project test1 (target: Desktop)
When executing build step 'Make'
@

yshurik

you may need to qmake+rebuild, also you may try to define at least virtual destructor

dangelog

http://doc.qt.nokia.com/4.7/debug.html#common-bugs

(moc wasn't run on your header, and/or the resulting cpp wasn't linked in. rerun qmake)

? Offline

Hi Guys,

Thanks for your help, I have moc and I have added
@
HEADERS +=
myclass.h
SOURCES += main.cpp
myclass.cpp
@

in my .pro file. I found my mistake, I must also add

@
CONFIG += qt
@

It works now, even though I don't know why. =)