Path: utzoo!attcan!uunet!mailrus!cs.utexas.edu!usc!rutgers!bpa!sjuphil!ryan
From: ryan@sjuphil.uucp (Patrick M. Ryan)
Newsgroups: comp.lang.misc
Subject: Re: do...while vs. repeat...until (was: Errors aren't that simple)
Message-ID: <1990Mar16.135706.28432@sjuphil.uucp>
Date: 16 Mar 90 13:57:06 GMT
References: <8192@hubcap.clemson.edu> <17000003@hpcvra.CV.HP.COM> <Mar.7.10.43.42.1990.17402@paul.rutgers.edu> <5819.25f7a840@vax1.tcd.ie> <16188@haddock.ima.isc.com>
Reply-To: ryan@sjuphil.UUCP (Patrick M. Ryan)
Organization: SJU Grad CSC
Lines: 30

In article <16188@haddock.ima.isc.com> karl@haddock.ima.isc.com (Karl Heuer) writes:
>In article <5819.25f7a840@vax1.tcd.ie> cbuckley@vax1.tcd.ie writes:
>>In article <Mar.7.10.43.42.1990.17402@paul.rutgers.edu>, emuleomo@paul.rutgers.edu (Emuleomo) writes:
>>> The other less serious flaw in C is the do...while contruct.
>>> I kind of prefer PASCAL's repeat....until construct myself.
>>
>That's enough to make it a (minor) flaw.  Judging from my own personal
>experience, it is more natural for a test-at-top loop to specify the condition
>for continuing (while), but for a test-at-bottom loop to specify the condition
>for terminating (until).  I don't know if there's been a study on this; in
>fact, I'm not entirely sure how to formalize the concept.

  a simple hack to fix this problem:

#define repeat    do
#define until(c)  while (!(c))

thus,

repeat {                                   do {
    statement;        becomes                    statement;
until(condition);                          while (!(condition))

easy, no?

-- 
patrick m. ryan                                                 saint joseph's
ryan@sju.edu  /  ryan%sjuphil.sju.edu@bpa.bell-atl.com              university
{bpa|burdvax|princeton|rutgers}!sjuphil!ryan                      philadelphia
pmr@gemini.gsfc.nasa.gov                                          pennsylvania