Initializing bit fields

[Kevin D. Quitt]

In article <1656 at crabcake> zhu at 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 at demott.com
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