CODEWITHSUNDEEP
c++
tangrs
tangrs

Reputation: 9930

Passing object pointer as pointer to base class

Is this code legal?

It crashes and I'm not sure if it's because of my programming environment (it's an embedded device) or because I've written dodgy code.

int foo(NGKGame * game) {
    game->init(); //Crashes here
    return 0;
}

int main() {
    NGKGame * game = new PlaneGame();
    game->init(); //This call is okay
    foo(game); 

    return 0;
}

NGKGame is the base class. PlaneGame is a derived class from NGKGame. init() is a pure virtual function in the base class but is implemented in PlaneGame.

Thanks,

Edit:

The init function being called twice is just as part of the example. In my current implementation, it's empty.

Upvotes: 0

Views: 104

Answers (4)

shekhar
shekhar

Reputation: 1420

The code looks fine. It might have to do with some compiler flags. I had a somewhat similar issue a while ago. A code which juggles around pointers, would work fine with no optimization flags (using gcc), but would crash with the -O3(optimization) turned on. I did not figure out how to get rid of that, so I just manually added various optimization flags that were enabled with -O3 and it worked fine.

Upvotes: 0

Filip Roséen
Filip Roséen

Reputation: 63797

There's nothing wrong with your snippet.

Though are you meant to call NGKGame::init twice or is it just part of your example code? My hunch is that something inside PlaneGame::init is malfunctioning when calling it again, if that is the case.

Upvotes: 0

David Grayson
David Grayson

Reputation: 87396

It's probably crashing because you are calling init() twice on the same object. Since you didn't show us the source code of init() I can't speculate on why it would crash, but it seems like a function named init should only be called once.

If you want a better answer, please see http://sscce.org/

Upvotes: 2

Keith
Keith

Reputation: 6834

This code is fine - assuming its OK for you to call init() twice.

That init() is PV in NGKGame is not a problem. The whole point of PVs is to allow you to call them in the manner of foo().

Upvotes: 1

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