Article View: comp.lang.modula2
Article #4594Re: "for" loops (was Re: C++ vs. Modula2)
From: Guy Harris
Date: Sat, 28 Jan 1989 05:23
Date: Sat, 28 Jan 1989 05:23
42 lines
1768 bytes
1768 bytes
>Actually, C's "for" can be duplicated EXACTLY by C's "do ... while"
>loops.
No, they can't.
for (i = 0; i < N; i++) /* N is a *variable* here */
stuff;
isn't duplicated by
i = 0;
do
stuff;
while (++i < N);
because, if N is 0, the first loop will be executed 0 times and the
second loop will be executed 1 time. It *is* duplicated by
i = 0;
while (i < N) {
stuff;
i++;
}
as long as "stuff" doesn't include a "continue" (see p. 60 of K&R
Second Edition; there's probably similar stuff somewhere in the First
Edition).
>These two iterations are indistinguishable from one another. The "for" term
>in C is totally superfluous and is only included because it makes it look like
>languages that have a more "for"-ish "for" statement, like Pascal or Modula.
Well, to quote something else from p. 60:
The "for" is preferable when there is a simple initialization
since it keeps the loop control statements close together and
visible at the top of the loop.
Whether you agree with that opinion or not is your business; however, it
seems the reason "for" was included wasn't solely to "make it look like
languages that have a more 'for'-ish 'for' statement", but because DMR
felt the "for" statement had merits of its own.
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Path: arc1-ca.pugleaf.net!utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cornell!batcomputer!itsgw!steinmetz!uunet!auspex!guy From: guy@auspex.UUCP (Guy Harris) Newsgroups: comp.lang.modula2,comp.lang.c Subject: Re: "for" loops (was Re: C++ vs. Modula2) Message-ID: <904@auspex.UUCP> Date: 28 Jan 89 05:23:12 GMT References: <INFO-M2%89011219330825@UCF1VM> <739@jupiter.iis.UUCP> <1611@csuna.UUCP> Reply-To: guy@auspex.UUCP (Guy Harris) Organization: Auspex Systems, Santa Clara Lines: 42