Re: Strings and reading from a file

[Marin David Condic <condicma@bogon.pwfl.com>]

Martin C. Carlisle wrote:
> 
> I can't imagine!  Probably something more like:
> 
> function Next_Line(File : in Ada.Text_IO.File_Type :=
>    Ada.Text_Io.Standard_Input) return String is
>    Answer : String(1..256);
>    Last   : Natural;
> begin
>    Ada.Text_IO.Get_Line(File => File,
>       Item => Answer,
>       Last => Last);
>    if Last = Answer'Last then
>       return Answer & Next_Line;
>    else
>       return Answer(1..Last);
>    end if;
> end Next_Line;
> 
This is a very clever and much more general solution than my original
code segment. (I must confess, I've seen this idiom before.) It has the
decided advantage that it will work for any length line and coupled with
the Unbounded_String type makes the most "polished" answer to the
original post. (If Cameron Hodge is still listening?) Obviously, it will
not incur any recursion overhead for most lines, so it has efficiency
working for it as well.

However - enamoured as I am with the "perfect" solution that works for
any case that may arise - I'd wonder if in practice it isn't a bit of
overkill. In my experience with text files, most lines are less than the
80 character width of a punchcard or glass-teletype. Probably 95% of
text lines are within twice that number. I can't recall ever seeing a
text line (in a standard text file like what would be used for some word
processing app - not a custom data file) which ever exceeded a 256 byte
string. 

Perhaps I'll have to dig up my newly minted statistics library and hack
together a little program to produce the descriptive statistics on line
length from some collection of text files - just so I know what length
to pick to get me to Six Sigma on the "defect rate"? Or would that
constitute proof that I have way too much time on my hands? (Well at
least its not as bad as the web page where someone translated the King
James Version of the Bible into Pig Latin! :-)

MDC
-- 
Marin David Condic
Real Time & Embedded Systems, Propulsion Systems Analysis
United Technologies, Pratt & Whitney, Large Military Engines
M/S 731-95, P.O.B. 109600, West Palm Beach, FL, 33410-9600
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