Hi!

I am playing with qt and wrote a program that looks like this:

main.cpp:

#include "qapplication.h"
#include "mainwindow.h"

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

MainWindow *mw = new MainWindow();
mw->setCaption("KDC");
mw->show();

app.connect(&app, SIGNAL(lastWindowClosed()), &app, SIGNAL(quit()));
return app.exec();
}




mainwindow.h:
g++ -I/usr/lib/qt3/include -c main.cpp
g++ -I/usr/lib/qt3/include -c mainwindow.cpp
g++ -o main main.o mainwindow.o -L/usr/lib/qt3/lib -L/usr/X11R6/lib/ -lqt -lX11 -lXext
mainwindow.o: In function `MainWindow::MainWindow(void)':
mainwindow.o(.text+0x1e): undefined reference to `MainWindow::QPaintDevice virtual table'
mainwindow.o(.text+0x25): undefined reference to `MainWindow virtual table'
collect2: ld returned 1 exit status
make: *** [kdc] Error 1
#ifndef classMainWindow
#define classMainWindow

#include "qmainwindow.h"
#include "qptrlist.h"
#include "qworkspace.h"

class MainWindow : public QMainWindow
{
Q_OBJECT
public:
MainWindow();
~MainWindow();

private:
//QWorkspace *ws;
QWorkspace* ws;
};

#endif



mainwindow.cpp:

#include "mainwindow.h"
#include "qvbox.h"

MainWindow::MainWindow()
{
QVBox *vb = new QVBox(this);
vb->setFrameStyle(QFrame::StyledPanel | QFrame::Sunken);
ws = new QWorkspace(vb);
ws->setScrollBarsEnabled(true);
setCentralWidget(vb);
}

Then I tried to compile this with a Makefile like this:

INCLUDEDIR = -I$(QTDIR)/include
LIBDIR = -L$(QTDIR)/lib -L/usr/X11R6/lib/
LIBS = -lqt -lX11 -lXext

kdc : main.o mainwindow.o
g++ -o main main.o mainwindow.o $(LIBDIR) $(LIBS)

main.o : main.cpp
g++ $(INCLUDEDIR) -c main.cpp

mainwindow.o : mainwindow.cpp
g++ $(INCLUDEDIR) -c mainwindow.cpp

but I always get this error:

g++ -I/usr/lib/qt3/include -c main.cpp
g++ -I/usr/lib/qt3/include -c mainwindow.cpp
g++ -o main main.o mainwindow.o -L/usr/lib/qt3/lib -L/usr/X11R6/lib/ -lqt -lX11 -lXext
mainwindow.o: In function `MainWindow::MainWindow(void)':
mainwindow.o(.text+0x1e): undefined reference to `MainWindow::QPaintDevice virtual table'
mainwindow.o(.text+0x25): undefined reference to `MainWindow virtual table'
collect2: ld returned 1 exit status
make: *** [kdc] Error 1

Does anybody know what I am doing wrong?
Please, help!

the code is supposed to look like this:

----- main.cpp: -------
#include "qapplication.h"
#include "mainwindow.h"

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

MainWindow *mw = new MainWindow();
mw->setCaption("KDC");
mw->show();

app.connect(&app, SIGNAL(lastWindowClosed()), &app, SIGNAL(quit()));
return app.exec();
}

---- mainwindow.h: ------
#ifndef classMainWindow
#define classMainWindow

#include "qmainwindow.h"
#include "qptrlist.h"
#include "qworkspace.h"

class MainWindow : public QMainWindow
{
Q_OBJECT
public:
MainWindow();
~MainWindow();

private:
//QWorkspace *ws;
QWorkspace* ws;
};

#endif

---- mainwindow.cpp ---
#include "mainwindow.h"
#include "qvbox.h"

MainWindow::MainWindow()
{
QVBox *vb = new QVBox(this);
vb->setFrameStyle(QFrame::StyledPanel | QFrame::Sunken);
ws = new QWorkspace(vb);
ws->setScrollBarsEnabled(true);
setCentralWidget(vb);
}


--- and the error message like this: ---
g++ -I/usr/lib/qt3/include -c main.cpp
g++ -I/usr/lib/qt3/include -c mainwindow.cpp
g++ -o main main.o mainwindow.o -L/usr/lib/qt3/lib -L/usr/X11R6/lib/ -lqt -lX11 -lXext
mainwindow.o: In function `MainWindow::MainWindow(void)':
mainwindow.o(.text+0x1e): undefined reference to `MainWindow::QPaintDevice virtual table'
mainwindow.o(.text+0x25): undefined reference to `MainWindow virtual table'
collect2: ld returned 1 exit status
make: *** [kdc] Error 1

I think your problem is you aren't running moc before the compile.

Qt isn't pure C++, it also uses a meta-object compiler (moc) which you need to run before g++. Doing this manually is a pain; using qmake to do it for you is a lot easier. Look at the Trolltech docs for information on qmake. (I believe in Qt < 3 there is a similar program called tmake).

If you don't have any classes qith Q_OBJECT at the top of them, you don't need to run the moc.

Alex

I'm Having the Same Exact Problem but how can I avoid getting these unexplained erros .

I'm using KDevelop where to add moc , Do I have to change the compiler command ??

when I paste down Tutorial Chapter 7 it works perfectly ????????????????????????????????????????

And If I wrote the exact same code it doesn't work

Please Answer Me ?

I'm Stuck and I can't move ????