From mboxrd@z Thu Jan  1 00:00:00 1970
From: Frank Klemm <pfk@fuchs.offl.uni-jena.de>
To: gcc@gcc.gnu.org
Subject: Re: Proposal
Date: Thu, 27 Sep 2001 07:09:00 -0000
Message-id: <20010927160755.D330@fuchs.offl.uni-jena.de>
References: <200109151841.UAA04064@fuchs.offl.uni-jena.de> <20010917235928.A11347@daikokuya.demon.co.uk> <20010918021527.A14623@fuchs.offl.uni-jena.de> <orpu8dyrmj.fsf@localhost.localdomain>
X-SW-Source: 2001-09/msg01093.html

On Thu, Sep 27, 2001 at 05:17:40AM -0300, Alexandre Oliva wrote:
> On Sep 17, 2001, Frank Klemm <pfk@fuchs.offl.uni-jena.de> wrote:
> 
> > For instance try to convert 
> 
> >    #define MILLION	MY_MERGE_5 ( 1, _, 000, _, 000 )
> 
> If you're going down this road, I'd rather just do
> 
> #define MILLION MERGE3(1, 000, 000)
> 
> where
> 
> #define MERGE3(a,b,c) a##b##c
> 
Everyone misinterprets this example.

This is not an example to write 'grouped' numbers.

It is an example what must be forbidden to be able to write a filter program
which removes '_' from numbers.

'_' should be allowed in numbers. It is allowed between the digits of
numbers in a C/C++ source _before_ preprocessing. It is not allowed between
digits which are 'created' during the preprocessor phase.

It is nearly impossible to write a filter which recognizes such '_'
and removes it. This is the reason for this rule. If gcc introduces a '_' in
numbers, such a filter is a MUST.


Exercise: 
  Write a program which translates the following C_99 program to C99:

------------------------------------------------------------------------
#include <stdio.h>

#define MY_MERGE_5(a,b,c,d,e)  a##b##c##d##e  
#define MILLION                MY_MERGE_5 ( 1, _, 000, _, 000 )
#define BILLION	               MY_MERGE_5 ( MILLION, _, 000, _, 000 )	// UK notation
#define VAR		       MY_MERGE_5 ( a, _, b, _, c )
#define VAR2		       MY_MERGE_5 ( a, b, c, d, e )

int  
main ( void ) 
{
    int        abc   = MILLION;
    int        VAR   = MILLION;
    long long  x     = BILLION;
    int        VAR2  = MILLION;

    printf ("%d %d %lld %d %d\n", abc, VAR, x, VAR2, abcde );
    printf ("1000000 1000000 1000000000000 1000000 1000000\n" );
    return 0;
}
-----------------------------------------------------------------------

-- 
Frank Klemm