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From: volpe@underdog.crd.ge.com (Christopher R Volpe)
Newsgroups: comp.lang.c
Subject: Comma operator: lvalue????
Message-ID: <10839@crdgw1.crd.ge.com>
Date: 7 Aug 90 18:05:19 GMT
Sender: news@crdgw1.crd.ge.com
Reply-To: volpe@underdog.crd.ge.com (Christopher R Volpe)
Lines: 24

Can someone with a copy of the standard tell me if the comma
operator produces an lvalue. This is one of the only operators
that K&R2 fails to mention whether or not it returns an lvalue.
My intuition at first would tell me no, but the following works
under GNU C:

main()
{
  int a,b;

  if (&a == &(a,b)) printf("I shouldn't see this\n");
  if (&b == &(a,b)) printf(" Test 1: address-of works properly.\n");
  (a,b)=4;
  if (b==4) printf("Test 2: Assignment works properly.\n");
}

I assume that if the comma operator EVER produces an lvalue, it does
so if and only if the right operand is an lvalue. Is this correct?

(Oh, BTW, sorry I forgot to sign my previous post about the macros)

Chris Volpe
GE Corporate R&D
volpecr@crd.ge.com