Path: utzoo!mnetor!uunet!mcvax!enea!sommar
From: sommar@enea.se (Erland Sommarskog)
Newsgroups: comp.lang.misc
Subject: FOR loops
Message-ID: <2853@enea.se>
Date: 15 Mar 88 22:21:09 GMT
References: <2827@enea.se> <1557@pasteur.Berkeley.Edu>
Reply-To: sommar@enea.UUCP(Erland Sommarskog)
Followup-To: comp.lang.misc
Organization: ENEA DATA AB, Sweden
Lines: 53

Wayne A. Christopher (faustus@ic.Berkeley.EDU) writes:
>In article <2827@enea.se>, sommar@enea.se (Erland Sommarskog) writes:
>> ... Ada as I see it have
>> the perfect solution: The loop variable is declared in the FOR-
>> statement, and is thus not accessible afterwards.
>
>Here's the problem with that construct:  I often write
>	for (i = 0; i < max; i++)
>		if (something)
>			break;
>	if (i == max)
>          ...
>If the loop variable is inaccessible outside of the loop there's
>no way to tell how it terminated, except by using an extra flag,
>which is ugly.

Sorry to be a little rude, but is just an argument for the Ada style.
I find your style ugly and Ada stops you using it. Why is it ugly?
Because you're using i in two ways here. First as an iterator, and the 
as a flag to se if "something" (dit not) occur. So the extra flag is not
ugly. Another point is that I would probably use a WHILE loop instead.

Some proposals: (in Ada)
-- WHILE a la Pascal
i := 0;
While i < max and not something loop
...
End loop;
-- Here you *can* test use i for the test, but I'd prefer "something"

-- FOR loop with exit-statement. 
For i in 0..max - 1 loop   -- And why not 1..max? But we have had that debate.
   Exit when something;
End loop;
If not something then    

-- Or if "something" is an error condition, use an exception handler
Begin
   For i in 0..max - 1 loop
   End loop
   Do_the_normal_stuff;
Exception
   when Something => Clean_up_or_re_raise;
End;
Continue_if_you_like;



-- 
Erland Sommarskog       
ENEA Data, Stockholm        
sommar@enea.UUCP           "Si tu crois l'amour tabou...
                            Regarde bien, les yeux d'un fou!!!" -- Ange