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From: Matthew Heaney <matthew_heaney@acm.org>
Subject: Re: get_line
Date: 1998/06/06
Message-ID: <m3d8cmgkjh.fsf@mheaney.ni.net>#1/1
X-Deja-AN: 360316709
References: <Pine.OSF.3.95.980605111447.22858A-100000@esus.cs.montana.edu>
 <dewar.897143686@merv> <m3zpfqu68v.fsf@mheaney.ni.net>
 <6lcql0$8qj$1@goanna.cs.rmit.edu.au>
Organization: Network Intensive
Newsgroups: comp.lang.ada
Date: 1998-06-06T00:00:00+00:00
List-Id: <comp.lang.ada>


Dale Stanbrough <dale@goanna.cs.rmit.edu.au> writes:

> Yes you are correct. I didn't write exactly what i should have, I can 
> now see! What i should have said is "if you do read in exactly the number
> of characters as are in the buffer, then you really don't know what
> situation you are in - you can still never tell if a skip_line was
> called".

I'm still confused by your answer.

I'm confused, because you definately can tell what state you're in, if
the buffer size is the same as the number of input characters, because
the rule for this case is "No, skip line is NOT called."

This very issue was the subject of an AI.

To determine when you're finished consuming all the text on a line, the
definitive test is

  if Last < Line'Last then
    <all done>
  else
    <there's more to read, possibly just a line terminator>
  end if;

Which is why I said to make the Line'Last greater than the maximum
number of input characters: so you can write that predicate.  I like to
do this:

declare
   Max_Length : constant Positive := <whatever>;
   Line : String (1 .. Max_Length + 1);
   Last : Natural;
begin
   Get_Line (Line, Last);

   if Last <= Max_Length then
      <we got all the input, including the line terminator>
   else
      <input line is too long for buffer; handle error>
   end if;
end;

If the user enters Max_Length characters, then all is well, and
Skip_Line is called automatically.

If the user enters more than max_length characters, then Skip_Line is
definately NOT called.  This you know, because the language says so.