On Feb 24, 2012, at 7:50 AM, Oleg Krupnov wrote:
> An interesting question. The following samples are equivalent in terms
> of compiled code, but which one is more correct from the language's
> point of view?
>
> self = [super init];
> if (self)
> {
> }
> return self;
>
> self = [super init];
> if (self != nil)
> {
> }
> return self;
>
> The Xcode samples promote the first variant, but I'm wondering if the
> second one is more correct?
It isn't. Both are valid methods of checking to see if some object is non-zero.
> I also heard that generally speaking NULL is not necessarily always
> equal to 0 on all architectures.
>
> Thoughts?
Where in the world did you hear that? From the C99 standard, 6.3.2.3 paragraph
3:
"An integer constant expression with the value 0, or such an expression cast to
type void *, is called a null pointer constant. If a null pointer constant is
converted to a pointer type, the resulting pointer, called a null pointer, is
guaranteed to compare unequal to a pointer to any object or function."
I suppose some compilers can ignore the standard and do their own thing, but
the compilers that come with Xcode are pretty good with standards compliance.
Nick Zitzmann
<http://www.chronosnet.com/>
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