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From: guy@auspex.UUCP (Guy Harris)
Newsgroups: comp.unix.wizards,comp.lang.c
Subject: Re: Old-fashioned assignment operators (was Re: braces
Message-ID: <746@auspex.UUCP>
Date: 17 Dec 88 21:28:18 GMT
References: <9076@smoke.BRL.MIL> <14020049@hpisod2.HP.COM> <212@UNIX386.Convergent.COM> <2151@uokmax.UUCP> <2155@uokmax.UUCP>
Reply-To: guy@auspex.UUCP (Guy Harris)
Followup-To: comp.lang.c
Organization: Auspex Systems, Santa Clara
Lines: 16

(Wow, a C question in comp.unix.*, rather than the other way around!)

>  The question I have is, what exactly *is* the correct interpretation of
>x=-y in modern C?

In sufficiently modern C, the interpretation is "assign the negative of
the value of 'y' to 'x'".

>What does the ANSI C standard say about this?

The dpANS says "=-" should not be interpreted as an assignment operator
(and the final standard, once it exists, will almost certainly say the
same thing).  The (non-dpANS-conformant) C compilers AT&T has
distributed with System V releases do not interpret it as such, and
more C compilers are picking this up (for instance, in SunOS 4.0,
support for "old-style assignment operators" went away).