From mboxrd@z Thu Jan  1 00:00:00 1970
X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me
X-Spam-Level: 
X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00 autolearn=ham
	autolearn_force=no version=3.4.4
X-Google-Language: ENGLISH,ASCII-7-bit
X-Google-Thread: 103376,51e0e3232c45c76c
X-Google-Attributes: gid103376,public
X-Google-ArrivalTime: 2001-06-11 09:29:07 PST
Path: 
 archiver1.google.com!newsfeed.google.com!newsfeed.stanford.edu!news-spur1.maxwell.syr.edu!news.maxwell.syr.edu!feed2.news.rcn.net!rcn!wn4feed!worldnet.att.net!135.173.83.71!wnfilter1!worldnet-localpost!bgtnsc05-news.ops.worldnet.att.net.POSTED!not-for-mail
Message-ID: <3B24F26E.E198252C@worldnet.att.net>
From: James Rogers <jimmaureenrogers@worldnet.att.net>
X-Mailer: Mozilla 4.76 [en] (Win98; U)
X-Accept-Language: en
MIME-Version: 1.0
Newsgroups: comp.lang.ada
Subject: Re: converting - adasockets
References: <20010611.085009.1789366143.627@zamek.gda.pl>
 <3b2498c9$1_2@Newsfeeds.com> <3B24AF5D.241C9743@Physik.Uni-Magdeburg.DE>
 <3B24EB7A.D2792E53@worldnet.att.net>
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
Date: Mon, 11 Jun 2001 16:29:07 GMT
NNTP-Posting-Host: 12.86.34.16
X-Complaints-To: abuse@worldnet.att.net
X-Trace: bgtnsc05-news.ops.worldnet.att.net 992276947 12.86.34.16 (Mon,
 11 Jun 2001 16:29:07 GMT)
NNTP-Posting-Date: Mon, 11 Jun 2001 16:29:07 GMT
Organization: AT&T Worldnet
Xref: archiver1.google.com comp.lang.ada:8555
Date: 2001-06-11T16:29:07+00:00
List-Id: <comp.lang.ada>

James Rogers wrote:
> 
> Gerald Kasner wrote:
> >
> > "David C. Hoos, Sr." schrieb:
> > >
> > > Assuming the following Ada declarations,
> > > S : String [1 .. 10];
> >
> > This is not an Ada declaration ! (Pascal,Modula-2,Oberon-2...??)
> >
> > > I : Integer;
> > >
> > Why unchecked conversion ?
> 
> Unchecked Conversion is necessary because the data is not a string
> representation of an integer, but an integer value returned as
> a string.  For instance, if the integer is represented as 32 bits,
> the string will be returned as a four byte string. Those four bytes
> need to be interpreted as an integer instead of as a string.
> 
> Ada provides two approaches for solving this problem.
> 
> The first is to use unchecked conversion as described by Mr.
> Hoos. The second is to define a string and an integer to occupy
> the same address. Simply copy the string from Adasockets into
> the overlayed string, then read the value as an integer.
> 
> The C code example used by the original poster showed the C
> equivalent of viewing a string as an integer. There was no conversion
> of values as would occur using the 'value attribute.

A simple example of defining an integer and a string to occupy the
same address follows:

-- Coversion between String and Integer when the string merely contains
-- the bit pattern for the integer, not the character representation
-- of the integer.
--
with Ada.Text_Io;

procedure Memory_Overlay is
   String_Rep : String(1..4);
   Integer_Rep : Integer;
   Num : Integer;

   for String_Rep'Address use Integer_Rep'Address;
begin
   Num := 0;
   while Num < 1024 loop
      Integer_Rep := Num;
      Ada.Text_Io.Put_Line("Integer_Rep:" & Integer'Image(Integer_Rep));
      Ada.Text_Io.Put_Line("String_Rep: " & String_Rep);
      Num := Num + 100;
   end loop;
end Memory_Overlay;

Jim Rogers
Colorado Springs, Colorado USA