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Class Inheritance and Constructors/Destructors

Jason2Jason · 2002-09-04T12:18:08

Hi, i did a search in the forums about this but didn''t find a clear answer. Say I have a base class: CBase, and it had a constructor to init some variables. Then I derive a class: CDerived : public CBase, which aslso has a constructor to init some of its own vars, will the first constructor get called then the constructor in the derived class be called next? Or will I have to rewrite the first constructer in the derived class? What about destructors? Will the base one be called then the new one in the derived class? Thanks, -J _____________________________________________ :S Confused? Me too! :S

General and Gameplay Programming Programming

Started by Jason2Jason September 03, 2002 12:37 PM

12 comments, last by Jason2Jason 21 years, 7 months ago

Sneftel

1,788

September 03, 2002 08:16 PM

quote:Original post by biovenger
No, the derived constructor gets called first, then the default base constructor (BaseClass(); {}).

You''re wrong. Have you even tried this?

Here''s some proof code.

  #include <iostream>class CBase{        public:        CBase() { std::cout << "CBase::CBase()\n"; }};class CDerived : public CBase{        public:        CDerived() { std::cout << "CDerived::CDerived()\n"; }};int main(){        CDerived myClass;        return 0;}

Gosh, it runs the base-class ctor first! fancy that!

Don''t listen to me. I''ve had too much coffee.

Gyzmo

162

September 04, 2002 11:37 AM

HELLOOOOO!!!!! has anybody paid any attention to my first post? I think it has illustrated it pretty conclusively, why are you still discussing this?

Gyzmo
==============================
"Well is the world standard" - The Alchemist
"Not in Canada!" - jonnyfish

Gyzmo=============================="Well is the world standard" - The Alchemist"Not in Canada!" - jonnyfish

Jason2Jason

166

Author

September 04, 2002 12:03 PM

yes i did, it works as you said, so if any one says other wise, they are wrong.

-J

siaspete

208

September 04, 2002 12:18 PM

If Gyzmo didn''t clear it up for you all, just write a small test app for yourselves.

// Create an object here, and the compiler will call these for you, in this order
CBase ()
CDerived ()
// It goes out of scope or gets deleted, the compiler will call these for you, in this order
~CDerived ()
~CBase ()

You should never have to call a destructor manually. You normally never have to call an constructor manually.

Also, always make your base class destructor virtual. Otherwise the derived one will not be called when you do this:

Base * p = new Derived;
delete p;

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