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Article #438Re: Array of unions
From: Joseph S. D. Yao
Date: Wed, 03 Jul 1985 01:51
Date: Wed, 03 Jul 1985 01:51
44 lines
2201 bytes
2201 bytes
In article <27694@lanl.ARPA> rmc@lanl.ARPA writes:
>> I defined an array of unions as follows:
>> typedef union {
>> unsigned char *bytes;
>> unsigned long *words;
>> } block;
>> block sched[NKEYS];
>> Now if I try to pass sched[i] as a parameter,
>> the C compiler bombs with "Fatal error in /lib/ccom".
> Here's an example of a program that didn't
>compile under 4.2/4.3bsd (VAX). The program DID
>compile on a SUN, or with the portable C compiler
>under SUMacC.
>#define NKEYS 20
> typedef union {
> unsigned char *bytes; unsigned long *words;
> } block;
> main()
> {
> block sched[NKEYS]; int i;
> i= 4; bar(i, sched);
> }
>
> bar (i, sched) block sched[];
> { foo(sched[i]); }
>
> foo (junk) block junk;
> { printf("%d\n",junk.bytes); }
As others have said, this should have worked. Potential problems/
perturbations to test:
(1) in bar(), try changing sched[] to *sched. As discussed ad
infinauseum elsewhere, this s h o u l d make no difference.
(2) in bar(), pass &sched[i]; and in foo(), declare block *junk;.
Also, of course, junk->bytes. The construct you use there is
relatively recent, and might cause problems that haven't been
encountered before. I know that passing structs as parameters
is now old hat, but I think some compilers handle unions a
little strangely. Addresses (as in the old days) might be
a bit better.
Good luck. Write if it's found to work.
--
Joe Yao hadron!jsdy@seismo.{ARPA,UUCP}
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Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/18/84; site hadron.UUCP Path: arc1-ca.pugleaf.net!utzoo!watmath!clyde!bonnie!akgua!whuxlm!harpo!decvax!genrad!panda!talcott!harvard!seismo!trwatf!rlgvax!prcrs!hadron!jsdy From: jsdy@hadron.UUCP (Joseph S. D. Yao) Newsgroups: net.bugs Subject: Re: Array of unions Message-ID: <212@hadron.UUCP> Date: Tue, 2-Jul-85 21:51:22 EDT Article-I.D.: hadron.212 Posted: Tue Jul 2 21:51:22 1985 Date-Received: Fri, 5-Jul-85 06:11:53 EDT References: <27676@lanl.ARPA> <27694@lanl.ARPA> Reply-To: jsdy@hadron.UUCP (Joseph S. D. Yao) Distribution: net Organization: Hadron, Inc., Fairfax, VA Lines: 44