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From: rmarti@sun.UUCP
Newsgroups: net.lang.c
Subject: Re: Precedent for use of =
Message-ID: <4824@sun.uucp>
Date: Mon, 7-Jul-86 13:44:55 EDT
Article-I.D.: sun.4824
Posted: Mon Jul  7 13:44:55 1986
Date-Received: Tue, 8-Jul-86 06:46:13 EDT
References: <1954@brl-smoke.ARPA>
Organization: Sun Microsystems, Inc.
Lines: 43

> Everybody keeps guessing at the reasons for the use of = for asignment
> and == for equality tests.  How about a different angle: how many times
> in a program do you assign something versus how many times you compare things?
> 
> [ ... ]
> 
> Maybe Mssrs. Kernighan and/or Ritchie would like to give some input on
> their reasons of choice.
> -------

They already did.  Let me quote K&R, p.17:

  The double equals sign == is the C notation for "is equal to" (like
  Fortrans's .EQ.).  This symbol is used to distinguish the equality
  test from the single = used for assignment.  Since assignment is about
  twice as frequent as equality testing in typical C programs, it's
  appropriate that the operator be half as long.

Personally, I still prefer := for assignment and = for equality over =
and ==.  I also think that the keystroke argument is ridiculous (flames
to /dev/null).  The problem with = and == is further aggravated by the
fact that in C an assignment is an expression and not a statement, so
that code like

  if (i = 0) {
    /* do something */
  }
  else {
    /* do something else */
  }

is legal C and usually  /* does something else */   than you expected  :-)

Despite that, I would never call Messrs K&R idiots, as Niklaus Wirth has
been labeled in a recent message (not the one I am responding to):
I think both C and Pascal have been reasonable designs of programming
languages and important contributions to the computing community.
-- 

Robert Marti, Sun Microsystems, Inc.

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