Date: Tue, 16 May 95 01:43:35 PDT
Reply-To: pdasilva AT tpone DOT telepac DOT pt (P. da Silva)
From: pdasilva AT tpone DOT telepac DOT pt (P. da Silva)
To: djgpp AT sun DOT soe DOT clarkson DOT edu
Subject: garbage at end of number [Was BUG or What?]

Thanks for all kind answers to my post "BUG OR WHAT".
Here is it and a summary of all responses I received:

> FILE TP.H
> #define CT 0x2000
> #define AA     (0xfd+CT)
> #define BB     (0xfe+CT)
> #define CC     (0xff+CT)
>
> FILE TP.C
> #include "tp.h"
> static int x[]={BB};
>
> Compiling this with GCC ver. 2.6.3 gives the error message
> tp.c:2: garbage at end of number
>
> But if you change to
> static int x[]={AA};
> or
> static int x[]={CC};
>
> it compiles OK.
>

The C language requires to have whitespace between a hex-number
ending in "e" and a subsequent "+" or "-".

There's a VERY good reason for this apparently bizarre rule.
Floating Point Constants.

E.g.
float a = 12e4;
float b = 13e-2;
/* peculiar but legal usage: */
float c = 0x10e+3;
/* which is NOT the same as: */
float d = 0x10e + 3;


Some GCC INFO follows:
======================

In the info-node `Incompatibilities', it says:

   * GNU C complains about program fragments such as `0x74ae-0x4000'
     which appear to be two hexadecimal constants separated by the minus
     operator.  Actually, this string is a single "preprocessing token".
     Each such token must correspond to one token in C.  Since this
     does not, GNU C prints an error message.  Although it may appear
     obvious that what is meant is an operator and two values, the ANSI
     C standard specifically requires that this be treated as erroneous.

     A "preprocessing token" is a "preprocessing number" if it begins
     with a digit and is followed by letters, underscores, digits,
     periods and `e+', `e-', `E+', or `E-' character sequences.

     To make the above program fragment valid, place whitespace in
     front of the minus sign.  This whitespace will end the
     preprocessing number.
..
If you pass Option `-ftraditional' to gcc, this, among other things,
happens:
        * Certain constructs which ANSI regards as a single invalid
          preprocessing number, such as `0xe-0xd', are treated as
          expressions instead.

Thanks again
Paulo