Re: Ada Idioms Progress Preview

[Ole-Hjalmar Kristensen <ohk@clustra.com>]

Ted Dennison<dennison@telepath.com> writes:

> In article <umqr8ug55d9.fsf@maestro.clustra.com>, Ole-Hjalmar Kristensen says...
> >One thing which can be said in favour of having a terminator character
> >is that it frees you from having to store the length explicitly. The
> >length of a string is usually different from the size of the array
> >used to store the string.
> 
> It frees you from that problem in *some* cases. I find that most of the time I
> don't change the string, so I can declare it perfectly sized. When you do that,
> you are not storing the length explicitly, but rather implicitly in the array
> bounds. As others have mentioned, you also don't have to iterate through every
> valid data element to derive this piece of implicit information like you do with
> C. Thus perfectly-sized Ada strings give you the best of both worlds.
> 

But you usually don't need to know the length of the string, precisely
because it has a sentinel value at the end :-)

Perfectly-sized C string are no problems either:

char x[] = "a perfect string";

I was thinking of the case where you cannot statically allocate a
perfectly sized string, which pops up whenever you have to get
variable sized strings from somewhere, as you describe below.

Btw., I'm not saying that C strings are superior in general or trying
to start a war, just that there are cases when using a sentinel value
makes sense.

> Unfortunately, the most notable exception to this is in reading data from
> Text_IO, which is also one of the first things a newbie will want to do with Ada
> strings. :-(
> 
> ---
> T.E.D.    homepage   - http://www.telepath.com/dennison/Ted/TED.html
>           home email - mailto:dennison@telepath.com


-- 
Kabelsalat ist gesund.

Ole-Hj. Kristensen