Path: utzoo!utgpu!water!watmath!clyde!ima!haddock!karl
From: karl@haddock.ISC.COM (Karl Heuer)
Newsgroups: comp.lang.c
Subject: min and max
Message-ID: <2254@haddock.ISC.COM>
Date: 14 Jan 88 01:43:27 GMT
References: <11182@brl-adm.ARPA> <2197@haddock.ISC.COM> <518@cresswell.quintus.UUCP>
Reply-To: karl@haddock.ima.isc.com (Karl Heuer)
Organization: Interactive Systems, Boston
Lines: 37

In article <518@cresswell.quintus.UUCP> ok@quintus.UUCP (Richard A. O'Keefe) writes:
>In article <2197@haddock.ISC.COM>, karl@haddock.ISC.COM (Karl Heuer) writes:
>> Actually, I'd give a higher wish-priority to min and max operators.  They
>> could have used "><" and "<>", respectively; the syntax would drive BASIC
>> and PASCAL users crazy!  :-)
>
>Some years ago the C compiler I used *did* have min (spelled "/\")
>and max (spelled "\/") operators.  These symbols are ever so much better
>because they are standard mathematical notation.

Okay, as long as you're careful not to put "/\" at the end of a line.
(ANSI Backslash continuation occurs before token scanning!)

>["lo \/ a /\ hi" is likely to generate less code than the macros would.]

Right.  One thing I like about that idiom is that, assuming lo <= hi, the
relative precedence/associativity of \/ and /\ is irrelevant.  In addition to
the usual min() and max() functions, I keep a med() function in my library:
med(lo, x, hi) returns lo \/ x /\ hi if lo <= hi; undefined if lo > hi.  (I
could easily remove the lo <= hi restriction and have it always return the
median of the three numbers, but I've never needed that functionality and I
wanted to keep the implementation simple.)

Of course, the assignment operators /\= and \/= would be great.  Think of all
the times you've ever written "if (x > xmax) xmax = x;".

>Do I think it would be a good idea to add the to the standard?  No.

Despite my posted enthusiasm for these and the exponentiation operator, I must
agree.  There isn't enough prior art.  I would like to see it become a common
extension, though.

What's the appropriate precedence for these operators?  (What was it on those
compilers that had this extension?)

Karl W. Z. Heuer (ima!haddock!karl or karl@haddock.isc.com), The Walking Lint
(Btw, I believe "><" and "<>" are used in SAS for min and max operators.)