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From: kwh@bentley.UUCP (KW Heuer)
Newsgroups: net.lang.c++
Subject: Re: Unintuitive semantics for initializing in for statements
Message-ID: <805@bentley.UUCP>
Date: Fri, 9-May-86 20:39:07 EDT
Article-I.D.: bentley.805
Posted: Fri May  9 20:39:07 1986
Date-Received: Sun, 11-May-86 04:25:37 EDT
References: <17195@rochester.ARPA> <5334@alice.uUCp> <101@cstvax.UUCP>, <224@tuck.nott-cs.UUCP>
Organization: AT&T Bell Laboratories, Liberty Corner
Lines: 30

In article <224@tuck.nott-cs.UUCP> nott-cs!anw (Andy Walker) writes:
>In article <101@cstvax.UUCP> db@cstvax.UUCP (Dave Berry) writes:
>> An alternative would be to have a 'for' expression - the same as a 'for'
>> statement except that it returns the value of the iteration variable on
>> exit.

Not all "for" statements *have* an iteration variable.

>	The trouble with all such suggestions is that there are too many
>things that a loop *could* deliver, and for every application that would
>make use of one such thing, there are equally worthy applications for all
>the others.  Further, there is always a cogent objection.  For example,
>you could return:
>
>   a)	The value that the iteration variable would have on the next cycle
>	[ie, the value that caused termination] -- but this could easily
>	be > maxint.

If so, you've already got a problem (probably infinite loop).  Remember, a
"for" is just a glorified "while".

>...	Better to have nothing than to spread such confusion!

I ran into these same problems some years ago when designing a language with
statement-expression equivalence.  I concluded that a loop has a void value.

In C++, it's not so bad having statements which are not expressions, because
you can just make a one-statement inline function and use "return".

Karl W. Z. Heuer (ihnp4!bentley!kwh), The Walking Lint