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From: Laurent Guerby <Laurent.Guerby@enst-bretagne.fr>
Subject: Re: Waiver question
Date: 1997/04/29
Message-ID: <fxrafuwcjp.fsf@boole.enst-bretagne.fr>#1/1
X-Deja-AN: 238069683
Sender: guerby@boole.enst-bretagne.fr
References: <33585385.C8D@lmtas.lmco.com> <dewar.861594356@merv>
 <m2k9luibub.fsf@acm.org> <1997Apr28.151327.1@eisner> <m2zpui69zn.fsf@acm.org>
Organization: ENST de Bretagne, Brest FRANCE
Newsgroups: comp.lang.ada
Date: 1997-04-29T00:00:00+00:00
List-Id: <comp.lang.ada>


Corey Minyard <minyard@acm.org> writes:
> [...] For instance, the following code (and I hope
> the kind readers of the newsgroup excuse me for using C, but it is
> more compact for this type of stuff):

   Sacrilege ! See below. ;-)

> int
> main()
> {
>    int a[4];
>    char *c;
> 
>    a[0] = 0; a[1] = 0; a[2] = 0; a[3] = 0;
>    c = (char *) a;
>    c[0] = 0x01;
>    c[1] = 0x02;
>    c[2] = 0x03;
>    c[3] = 0x04;
>    printf("%x %x %x %x\n", a[0], a[1], a[2], a[3]);
>    return 0;
> }

   Here a somewhat equivalent Ada code, people can judge the
"compactness": 

with Ada.Text_IO;         use Ada.Text_IO;
with Ada.Integer_Text_IO; use Ada.Integer_Text_IO;
with Interfaces;          use Interfaces;
procedure Main is
   A : array (1..4) of Integer   := (others => 0);
   C : array (1..4) of Integer_8 := (1, 2, 3, 4);   
   for C'Address use A'Address;
begin
   Put (A (1), 12, 16);   Put (A (2), 12, 16);
   Put (A (3), 12, 16);   Put (A (4), 12, 16);
   New_Line;
end Main;           

   Of course in Ada the "with" clauses are mandatory (not the case of
#include in C. If you want to use the C printf, you can also do it, it
removes a few Ada IO with clauses:

procedure printf (Fmt : String; A, B, C, D : Integer);
pragma Import (C, printf);
...
printf ("%x %x %x %x" & ASCII.LF, A (1), A (2), A (3), A (4));

> on the Alpha will print:
> 	1020304 0 0 0
> and on the C40 will print:
> 	1 2 3 4
> because on the C40 a char and an int are the same size because the
> minimum size of any addressable unit is 32-bits.

   On Intel/Linux/GNAT I get

 16#4030201#       16#0#       16#0#       16#0# 

   or

4030201 0 0 0

> Corey Minyard               Internet:  minyard@acm.org
>   Work: minyard@nortel.ca       UUCP:  minyard@wf-rch.cirr.com

-- 
Laurent Guerby <guerby@gnat.com>, Team Ada.
   "Use the Source, Luke. The Source will be with you, always (GPL)."