Date: Sat, 06 Mar 1999 11:00:05 -0800 (PST) From: John Polstra <jdp@polstra.com> To: Nate Williams <nate@mt.sri.com> Cc: current@FreeBSD.ORG Subject: Re: callout changes nit Message-ID: <XFMail.990306110005.jdp@polstra.com> In-Reply-To: <199903061736.KAA24445@mt.sri.com>
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Nate Williams wrote:
>> > +void
>> > +callout_init(c)
>> > + struct callout *c;
>> > +{
>> > + bzero(c, sizeof c);
>> > }
>> >
>> > That doesn't look correct, does it?
>>
>> Agreed. I think it should be "sizeof *c".
>
> Ahh, I see. I think it should say
>
> bzero(c, sizeof(struct callout));
>
> To avoid the compiler using the size of the pointers et. al.
This is largely a matter of taste, so we don't need to agree on it. :-)
But I do have a specific reason for preferring the "sizeof *c"
form. Namely, it reduces redundancy. The advantage is best seen if
you consider making a macro for clearing a structure. Here are two
possibilities:
#define CLEAR_STRUCT(ptr) bzero((ptr), sizeof *(ptr))
#define CLEAR_STRUCT(ptr, type) bzero((ptr), sizeof(type))
In this context, the 1-parameter form is indisputably less
error-prone. Of course, the context of the original example was
different. So I'm satisfied to say we are both "right".
John
---
John Polstra jdp@polstra.com
John D. Polstra & Co., Inc. Seattle, Washington USA
"Nobody ever went broke underestimating the taste of the American public."
-- H. L. Mencken
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