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Re: Help on gcc


On Tue, 5 Feb 2002, James Dressler wrote:

> For those that believe in "Free Software": read carefully the e-mails 
> exchanged between me and Mr. Oliva, who answers by GCC (a free C++ 
> Compiler)...
> 
> ------------------------------------------------------------------
> Here begins my answer to you, Mr. Oliva:
> 
> It's a simple example, only to show the point.
> 
> I'm happy to tell you that it's impossible, on a operational system like 
> Solaris, Windows NT, Windows 2000, Linux and any other Unix-like system, to 
> "destroy the world" using a NULL pointer, because this is a logical address.

Actually, since it's undefined, it could do whatever it wanted to.
It has nothing to do with MMU's.

> There is a Memory Management Unit to map the logical address to physical 
> address, what make impossible that using a NULL pointer do any harm.

Sorry, what you did with it is undefined, the compiler can do whatever it 
wants as a result.
Period.
>  And I'm 
> just using a not too much technical language, to make it easier for you to 
> understand.
I'm sure you don't need to.

> 
> Imagine, for example, that it's not a NULL pointer, but a pointer that 
> dereferences an area of memory, previously allocated using "new", that has 
> been already returned to the operational system by a "delete" statement. It 
> will not work too. No exception raised.
Nor is one required to be.
> 
> For your information, although I think you already know, it works on 
> Microsoft C++ Compiler, and many others C++ Compilers. To be happy, like you 
> said, it's better to go with them. 
If you want non-standard behavior that Microsoft C++ gives you, 
then use it.
> Probably you think that gcc is a joke, 
> something to play with. 
No, he doesn't.
> You convinced me.
> 
> And I don't see any relation between my sister and C++. 
It was, of course, a joke.
> I guess if someone at Microsoft gave me an awful answer like you, what would happen to him. 
He'd charge you 300 bucks?

> Probably, he would be fired. That's what you deserve.
> 
> Best regards
> James M. Dressler
> 
> 
> >From: Alexandre Oliva <aoliva@redhat.com>
> >To: "James Dressler" <jamesmdr@hotmail.com>
> >CC: gcc@gcc.gnu.org
> >Subject: Re: Help on gcc
> >Date: 05 Feb 2002 19:10:26 -0200
> >
> >On Feb  5, 2002, "James Dressler" <jamesmdr@hotmail.com> wrote:
> >
> > > does not work, never prints "captured"
> >
> >Dereferencing a NULL pointer invokes undefined behavior, so the crash
> >you get is in perfect accordance with the Standard, and it is indeed
> >the expected behavior.  In fact, be happy that the program didn't
> >format your hard disk, destroy the universe nor go out with your
> >sister :-)  It might throw an exception, but that's not what most would
> >expect from C++ programs in this situation.  C++ != Java :-)
> >
> >--
> >Alexandre Oliva   Enjoy Guarana', see http://www.ic.unicamp.br/~oliva/
> >Red Hat GCC Developer                  aoliva@{cygnus.com, redhat.com}
> >CS PhD student at IC-Unicamp        oliva@{lsd.ic.unicamp.br, gnu.org}
> >Free Software Evangelist                Professional serial bug killer
> 
> 
> 
> 
> 
> James Masi Dressler
> 
> DBKi Software
> ===============
> www.dbki.com.br
> ===============
> 
> 
> _________________________________________________________________
> Chegou o novo MSN Explorer. Instale jŠ. … gratuito: 
> http://explorer.msn.com.br
> 


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