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

From: David Abrahams (dave_at_[hidden])
Date: 2007-10-01 20:03:12

on Fri Sep 21 2007, "Marco Servetto" <marco.servetto-AT-gmail.com> wrote:

> 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);

C++ guarantees very, very little about reinterpret_cast, and certainly
not that.  In general the results of reinterpret_cast are
implementation-defined.

-- 
Dave Abrahams
Boost Consulting
http://www.boost-consulting.com