"undefined reference for vtable" problem

[jepessen]

Hi.

I've downloaded a simple application to see how I can draw using Opengl.

The project has only the main.cpp that have the following code:

#include <QtGui/QApplication>
#include <QGLWidget>
#include <QHBoxLayout>
#include <QSize>
#include <QPushButton>
 
class MyGLWidget : public QGLWidget
{
    Q_OBJECT
public:
    MyGLWidget (QWidget* parent ) : QGLWidget(parent)
    {
    }
    float red, blue, green;
    void initializeGL()
    {
        red = 0;
        blue = 0;
        green = 0;
    }
 
public slots:
 
    void resetColor()
    {
        red = 0;
        blue = 0;
        green = 0;
        update();
    }
 
    void paintGL()
    {
        red += 0.007;
        blue += 0.002;
        green += 0.005;
        glClearColor(red,green,blue,0);
        glClear(GL_COLOR_BUFFER_BIT);
    }
};
 
 
class MiaMainWindow:public QWidget
{
public:
    MiaMainWindow ():QWidget(NULL){
        MyGLWidget *glWidget = new MyGLWidget(this);
        QHBoxLayout *layout = new QHBoxLayout(this);
        QPushButton *button = new QPushButton("Get to the Choppa!!!", this);
        setLayout(layout);
        layout->addWidget(glWidget);
        layout->addWidget(button);
        connect(button, SIGNAL(clicked()),glWidget, SLOT(resetColor()));
        setWindowTitle("Hello World!");
        sizeHint();
    }
 
    QSize sizeHint() const
    {
        return QSize(100,100);
    }
 
};
 
int main(int argc, char** argv){
 
    QApplication app(argc, argv);
    MiaMainWindow win;
    win.show();
    int res = app.exec();
    return res;
}

#include <QtGui/QApplication>
#include <QGLWidget>
#include <QHBoxLayout>
#include <QSize>
#include <QPushButton>

class MyGLWidget : public QGLWidget
{
    Q_OBJECT
public:
    MyGLWidget (QWidget* parent ) : QGLWidget(parent)
    {
    }
    float red, blue, green;
    void initializeGL()
    {
        red = 0;
        blue = 0;
        green = 0;
    }

public slots:

    void resetColor()
    {
        red = 0;
        blue = 0;
        green = 0;
        update();
    }

    void paintGL()
    {
        red += 0.007;
        blue += 0.002;
        green += 0.005;
        glClearColor(red,green,blue,0);
        glClear(GL_COLOR_BUFFER_BIT);
    }
};


class MiaMainWindow:public QWidget
{
public:
    MiaMainWindow ():QWidget(NULL){
        MyGLWidget *glWidget = new MyGLWidget(this);
        QHBoxLayout *layout = new QHBoxLayout(this);
        QPushButton *button = new QPushButton("Get to the Choppa!!!", this);
        setLayout(layout);
        layout->addWidget(glWidget);
        layout->addWidget(button);
        connect(button, SIGNAL(clicked()),glWidget, SLOT(resetColor()));
        setWindowTitle("Hello World!");
        sizeHint();
    }

    QSize sizeHint() const
    {
        return QSize(100,100);
    }

};

int main(int argc, char** argv){

    QApplication app(argc, argv);
    MiaMainWindow win;
    win.show();
    int res = app.exec();
    return res;
}

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and the .pro is the following one:

#-------------------------------------------------
#
# Project created by QtCreator 2011-09-14T20:01:51
#
#-------------------------------------------------
 
QT       += core
QT       += gui
QT       += opengl
 
TARGET = tryme
CONFIG   += console
CONFIG   -= app_bundle
TEMPLATE = app
SOURCES += main.cpp

#-------------------------------------------------
#
# Project created by QtCreator 2011-09-14T20:01:51
#
#-------------------------------------------------

QT       += core
QT       += gui
QT       += opengl

TARGET = tryme
CONFIG   += console
CONFIG   -= app_bundle
TEMPLATE = app
SOURCES += main.cpp

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But, when I compile it (using qtcreator 2.3.0 with Qt 4.7.4 and MinGW 4.4), I've the following errror:

debug/main.o: In function `MyGLWidget':
dir\tryme-build-desktop-Qt_4_7_3_for_Desktop_-_MinGW_4_4__Qt_SDK__Debug/../tryme/main.cpp:12: undefined reference to `vtable for MyGLWidget'
dir\tryme-build-desktop-Qt_4_7_3_for_Desktop_-_MinGW_4_4__Qt_SDK__Debug/../tryme/main.cpp:12: undefined reference to `vtable for MyGLWidget'
collect2: ld returned 1 exit status
mingw32-make[1]: *** [debug\tryme.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 tryme (target: Desktop)
When executing build step 'Make'

I've read something about this error but I don't know where's the error. Can anyone help me, please?

Thanks in advance for your replies.

Regards.

[wysota]

qmake only looks for Q_OBJECT macro in header files. So either move your class definition to a header file (and add it to your project and rerun qmake) or force running moc on your main.cpp by writing #include "main.moc" under the class definition (and rerun qmake).

[kalgorithmist]

That's strange, but try to remove the Q_OBJECT macro from the class definition.

[jepessen]

Really thanks. It solved my problem :-)