Re: abs function question

[Nathan Myers <ncm-nospam at cantrip dot org>]

On Tue, Jul 29, 2003 at 08:00:19AM +0200, Gabriel Dos Reis wrote:
> Nathan Myers <ncm-nospam@cantrip.org> writes:
> 
> | On Tue, Jul 29, 2003 at 06:39:30AM +0200, Gabriel Dos Reis wrote:
> | > Steve Ellcey <sje@cup.hp.com> writes:
> | > 
> | > | I am currently running into a problem with the function abs and the
> | > | header std_cstdlib.h.  
> | > 
> | > Huh!?  How can an inline definition could possibly clash with a using
> | > declaration?  Some piece of information is missing.  Could tell us
> | > more about that inline declaration?
> | 
> | I think he's saying that if __cplusplus is defined, no abs is declared 
> | at all, 
> 
> How do you read that from 
> 
>    The problem is that my system's stdlib.h header file is smart enough to
>    not do an extern declaration for abs if it is in C++ mode and *instead
>    does an inline declaration of the abs function*. 
> 
> ?

Selective garbling.  If the original question doesn't make sense, try 
small perterbations.  An "inline declaration" doesn't mean anything.
Maybe the header assumes it *will* be defined inline, or maybe it 
defines a macro if not in C++.  Obviously we can't be sure without
more information.  All we do know is that is doesn't work now.

It would be an unfortunate choice to use ::abs, generally, because in
C it's not going to be defined inline.  In C there's generally a macro 
abs() hiding it, which we have to #undef because it doesn't scope.  
Leaving it undeclared in their header allows C++ to define both ::abs 
(extern) inline and std::abs aliased to it, or vice versa.

Nathan Myers
ncm-nospam@cantrip.org