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From: kdq@demott.COM (Kevin D. Quitt)
Newsgroups: comp.lang.c
Subject: Re: Initializing bit fields
Message-ID: <343@demott.COM>
Date: 29 Jun 90 00:15:53 GMT
References: <1656@crabcake>
Reply-To: kdq@demott.COM (Kevin D. Quitt)
Organization: DeMott Electronics Co., Van Nuys CA
Lines: 39

In article <1656@crabcake> zhu@cs.jhu.edu (Benjamin Zhu) writes:
>>"All unnamed structure or union members are ignored during initialization."
>>ANSI 3.5.7 (page 72, line 38)  Thus the middle zero initializes
>>field2.
>>
>
>	That is what I thought before. However, after I tried this out
>	with my gcc compiler, it turns out that at least gcc is not doing
>	what I expected. Here is an example.
>
>main(void)
>{
>	struct  {
>		unsigned int	field1 : 2;
>		unsigned int	field2 : 2;	/* unsigned int field2 :2, */
>		unsigned int	       : 2;	/*                     :2; */
>		unsigned int	fieldn : 2;
>	}  mask = { 1, 1, 1 };
>
>	printf("%u %u %u\n", mask.field1, mask.field2, mask.fieldn);
>}
>
>	Guess what's the printout?
>
>	1 1 0			/* should be 1 1 1 according to ANSI */

    What version are you running, and on what machine? gcc 1.37.1 on a
Motorola Delta 3000 series (680x0) produces the correct results, as does
the native compiler.  (THAT was a surprise - of course, I had to move the
struct out of the main function and remove the void parameter).


-- 
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Kevin D. Quitt         demott!kdq   kdq@demott.com
DeMott Electronics Co. 14707 Keswick St.   Van Nuys, CA 91405-1266
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