Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!gatech!ncar!tank!mimsy!chris
From: chris@mimsy.UUCP (Chris Torek)
Newsgroups: comp.lang.c
Subject: Re: int divided by unsigned.
Message-ID: <18306@mimsy.UUCP>
Date: 28 Jun 89 04:10:04 GMT
References: <18296@mimsy.UUCP> <13959@lanl.gov>
Distribution: na
Organization: U of Maryland, Dept. of Computer Science, Coll. Pk., MD 20742
Lines: 39

In article <13959@lanl.gov> jlg@lanl.gov (Jim Giles) writes:
>In every other programming language I am familiar with, integer division
>is guaranteed to produce a result which is smaller than (or equal to)
>the numerator in absolute value.  That is, you can count on the following
>relation:
>            | a/b | <= | a |

Well, you can count on it in C, too, because in `unsigned a; int b; a/b'
you have unsigned division, rather than integer division; I find this
no more odd than the fact that `a/b' is sometimes integer division and
sometimes floating point division.  But maybe I am just used to it.

>Other languages which have unsigned either don't allow mixed mode at all
>(like Modula I, II, etc)

This I dislike (purely as a matter of taste), although as long as there
is a mechanism for explicit conversions, the language has not lost any
abilities.

>or they treat unsigned as inferior to inferior to signed for automatic
>conversion.  This later decision conforms to intuition (ie. the relation
>above) more often than the procedure C uses.

That depends on where you get your intuition.  I never would have
expected people to put up with traffic jams either---it seems
intuitively obvious that people would agree to flexible work hours
instead, at least in jobs that permit it (most `white collar' work).
That is, arrive any time between 0600 and 1000---sort of an extended
version of `flex time'.  But maybe that has something to do with
me getting up at 1800 one day, 2250 the next, and around 0200
the day after. . . .

Anyway, I happen to like `sticky unsigned' operation, but as I say,
perhaps I am just used to it.  It seems to me that a C-like language
with `sticky signed' operation would work as well, although the
results of such mixed mode operations would astonish me for a while.
-- 
In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 7163)
Domain:	chris@mimsy.umd.edu	Path:	uunet!mimsy!chris