Re: Multiple inheritance and pointer equivalence

From:
"Thomas J. Gritzan" <phygon_antispam@gmx.de>
Newsgroups:
comp.lang.c++
Date:
Wed, 02 Dec 2009 00:25:01 +0100
Message-ID:
<hf48kj$33i$1@newsreader3.netcologne.de>
io_x schrieb:

"io_x" <a@b.c.invalid> ha scritto nel messaggio
news:4b0f84ec$0$10444$4fafbaef@reader2.news.tin.it...

"Danny Woods" <dannywoodz@yahoo.co.uk> ha scritto nel messaggio
news:50skccrsex.fsf@gmail.com...

Hi all,

Given this simple program:

----

#include <cstdio>

class A { public: virtual ~A() {} };
class B { public: virtual ~B() {} };
class C : public A, public B { public: virtual ~C() {} };

int main(void)
{
 C *c = new C();
 A *a = c;
 B *b = c;

 printf("c: %p; a: %p; b: %p\n", c, a, b);

 delete c;
 return 0;
}

----

i not find in the example above no double free;
where is it?


There's no double delete in this code. The double delete occured in
another usage/situation the OP described.

where is the problem?
the debugger show that the call for construction
are C()A()B()
and for distruction ~C()~B()~A()
(this mean that printf print someting wrong here below)
where is the problem?

A()B()C()
c: 00852FC0; a: 00852FC0; b: 00852FC8
~C(); this=00852FC0
~B(); this=00852FC8
~A(); this=00852FC0
END


Your debugger is wrong. The base classes are constructed first, followed
by the derived class.

--
Thomas

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