How to Fix undefined reference to vtable

I was working on reorganising some code when I came across the following error which stumped me for ages. I was trying to move a class out of "Simulation.h/Simulation.cp" and into "SceneWindow.h/SceneWindow.cp".

make -k -s
Simulation.o: In function `~TSceneWindow':
/home/binh/Documents/polyworld/app/Simulation.cp:6392: undefined reference to `vtable for TSceneWindow'
/home/binh/Documents/polyworld/app/Simulation.cp:6392: undefined reference to `vtable for TSceneWindow'
/home/binh/Documents/polyworld/app/Simulation.cp:6392: undefined reference to `vtable for TSceneWindow'
/home/binh/Documents/polyworld/app/Simulation.cp:6392: undefined reference to `vtable for TSceneWindow'
/home/binh/Documents/polyworld/app/Simulation.cp:6392: undefined reference to `vtable for TSceneWindow'
Simulation.o:/home/binh/Documents/polyworld/app/Simulation.cp:6392: more undefined references to `vtable for TSceneWindow' follow
collect2: ld returned 1 exit status
make: *** [Polyworld] Error 1
make: Target `first' not remade because of errors.

Compilation exited abnormally with code 2 at Thu Mar  5 02:51:00

The solution was to ensure that I placed a reference to "SceneWindow.h" in my "Makefile". In my case I needed to place the reference in my ".pro" file and then use "qmake" to generate a "Makefile".

This took me hours to figure out. Grr.

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9/6/2011

A few people have kindly shared their tips.

Anonymous suggested

• running qmake and then re-building

miformaprohibidaenlibertad suggested

• This problem is also related with virtual functions. A common reason of the "vtable" message is not declaring a virtual function equal to zero, for example virtual foo(); instead of virtual foo() = 0;

I suggest that you first make sure that you are including all the necessary header files in your Makefile. I had to do this because I was writing my Makefiles manually.

If you are using Qt, you can rely on qmake to include all the necessary header files in your Makefile as long as you double check that you have included all the necessary header files in your ".pro" file.

Finally, try making your virtual functions into pure virtual functions by setting them equal to zero. I'm not sure whether this will work but it's another good option that you can try.

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