Re: I hate

Or it can insert empty space between consecutive members of a struct
(think union-of-structs) to improve data alignment.

  - a


Brian Alliet <[email protected]> writes:
> On May 13, 2004, at 9:25 AM, Andrew Kohlsmith wrote:
>
>> ... Why shouldn't it work?  I don't know Pascal but I was under the
>> impression
>> that was the *specific* reason for unions in C.
>
> Say that in comp.lang.c and you'll get yourself killed :) (check the
> archives in google, they're vicious in there).
>
>> union {
>> 	short s1;
>> 	int i1;
>> 	long l1; } mystuff;
>>
>> mystuff.l1 = 0xffffffff;
>> mystuff.i1 = 0xaaaa;
>> mystuff.s1 = 0x00;
>>
>> mystuff.l1 should now be 0xffffaa00, should it not?
>
> Certainly not. For all you know sizeof(short) == sizeof(int) ==
> sizeof(long). Even if they aren't you don't know what endianness the
> target platform is. And even if you know all that. The compiler can
> perfectly legally treat the above as just a plain old struct and not
> have the  memory overlapping at all!
>
> -Brian
>
>
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