C99: Suggestions for style(9)

[Christoph Mallon]

Zaphod Beeblebrox schrieb:
> On Fri, May 1, 2009 at 4:30 AM, Julian Elischer <julian at elischer.org> wrote:
> 
>> As an old-fart I have found many cases where what I thought was
>> a silly style rule, turned out to save my work in some way.
>>
>> Christoph Mallon wrote:
>>
>>
>>
>>>>    struct foo *fp;
>>>>    struct bar *bp;
>>>>
>>>>    fp = get_foo();
>>>>    if (!fp) return;
>>>>    bp = fp->bp;
>>>>
>>>> this can't easily be translated to the more natural:
>>>>
>>>>    struct foo *fp = get_foo();
>>>>    struct bar *bp = fp->bp;
>>>>
>> Well more natural for you, but not necessarily for everyone,
>> and NOT the same as what is there now, as you noticed.
>>
>>
>>
>>>> since really you'd want to write:
>>>>
>>>>    struct foo *fp = get_foo();
>>>>    if (!fp) return;
>>>>    struct bar *bp = fp->bp;
>>>>
>>>> which isn't legal in 'C'.  However, we have enough where this isn't
>>>>
>>> You're mistaken, this is perfectly legal C. See ISO/IEC 9899:1999 (E)
>>> §6.8.2:1. In short: you can mix statements and declarations.
>>>
> Sure, but it's still very  bad: If I'm not mistaken, this would mean that
> "bp" would only be valid within the "if" clause --- which isn't very useful.

You are mistaken. Re-read the "if": It already contains a "return;" as 
then-part. The declaration of "bp" has no relation to the "if".
In fact this is very good: "bp" can only be used after the "if", because 
it is declared after it. Further, it most probably is only assigned a 
value once, so declaration and the signle assignment are in the same 
place, which aids readability and makes the code more concise.

	Christoph