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-Thread: 103376,4819e43c270862a9
X-Google-Attributes: gid103376,domainid0,public,usenet
X-Google-Language: ENGLISH,ASCII
Path: 
 g2news2.google.com!news1.google.com!newsfeed.stanford.edu!headwall.stanford.edu!newsfeed.news2me.com!newsfeed.icl.net!newsfeed.fjserv.net!oleane.net!oleane!hunter.axlog.fr!nobody
From: Jean-Pierre Rosen <rosen@adalog.fr>
Newsgroups: comp.lang.ada
Subject: Re: Newbie Question: Integer_IO an Data_error
Date: Fri, 27 Mar 2009 09:59:22 +0100
Organization: Adalog
Message-ID: <gh4iqg.09i.ln@hunter.axlog.fr>
References: <873ad0ueva.fsf@babel.localdomain>
 <Wp6dnQTpg6rFYlbUnZ2dnUVZ8tudnZ2d@posted.plusnet>
NNTP-Posting-Host: mailhost.axlog.fr
Mime-Version: 1.0
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: 8bit
X-Trace: s1.news.oleane.net 1238135995 16104 195.25.228.57 (27 Mar 2009
 06:39:55 GMT)
X-Complaints-To: abuse@oleane.net
NNTP-Posting-Date: Fri, 27 Mar 2009 06:39:55 +0000 (UTC)
User-Agent: Thunderbird 2.0.0.21 (Windows/20090302)
In-Reply-To: <Wp6dnQTpg6rFYlbUnZ2dnUVZ8tudnZ2d@posted.plusnet>
Xref: g2news2.google.com comp.lang.ada:5333
Date: 2009-03-27T09:59:22+01:00
List-Id: <comp.lang.ada>

Tim Rowe a �crit :
> Zachary Kline wrote:
>> The problem comes with Data_errors: if I try to
>> handle that case the same way, we get a seemingly infinite loop.
> 
> 
> I'm an Ada newbie too, but the first thing I wonder is what Get does
> with the input characters if they don't match the expected type. I
> wonder whether it leaves them on the input stream -- in which case
> subsequent attempts to read the input will try to read the same
> characters each time. Until somebody who knows what they're talking
> about comes along (won't be long) I'd try doing a string Get after a
> failed numeric get, to see what's still in the input stream.

When a character is incorrect, the current position stays on it, to
allow you to do a Get(Char) and see what happened. OTOH, it means that
you must do a skip_line to get rid of the remaining of the line, and get
a fresh one. A typical reading loop is:

loop
   begin
      Get (N);
      exit;    -- OK, no exception
   exception
      when Data_Error =>
         Skip_Line;
         Put_Line ("Error, try again");
   end;
end loop;

-- 
---------------------------------------------------------
           J-P. Rosen (rosen@adalog.fr)
Visit Adalog's web site at http://www.adalog.fr