Re: Multiple inheritance and pointer equivalence

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;
}

----

Is it to be expected that the addresses stored in a and b are different?

I've tried this with Visual C++ and Cygwin g++, with identical results.

The problem I have is that there are other subclasses of A and B that
are distinct, but that there's a special case where the combined
subclass, C, is required to fill both roles. When the code that cleans
up a and b runs later, I'll end up with double deletion

unless I can
reliably tell that a and b point to the same object, but the simple
'a == b' doesn't work here.