[boost] reinterpret_cast : differents structs or classes with identical structural type

From: Marco Servetto (marco.servetto_at_[hidden])
Date: 2007-09-22 01:38:39

Hello,
Supposing having
struct A{
  int a1;
  double a2;
  int a3[3];
  };
struct B{
  int b1;
  double b2;
  int b3[3];
  };

A and B are two structure with same strucutural type but different
name, (and different name for fields...)

The question is: C++ grants that
A a;
a.a2=8.8;
assert(reinterpret_cast<B*>(&a)->b2==8.8);

If the response is yes,
it is even true for classes with inheritance?
that is A1,B1,C1 have same struttural type of A2,B2,C2 and
class A1 :public B1, class B1: public C1
and
class A2 :public B2, class B2: public C2
can i safaly reinterpreter cast from A1 to A2 and acceding public
fields (of A1,B1,C1)
trought the field names of A2?

Thanks in advance for your help.