On Sep 6 2007 12:23, David Miller wrote:
quoted text
>>     return copied ? : err;
>>   }
>> 
>> Shouldn't this read:
>> 
>>     return copied ? copied : err;
>> 
>> Or am I missing something?
>
>These two statements are equivalent, the first version is
>a shorthand allowed by gcc.

Not only that. With x?x:z, x is evaluated twice,
while with x?:z, x is only evaluated once. That's for stuff when you 
want to, say [dumb example follows],

size_t my_read(..) {
    return read(..) ? : -1
}

and the only other way would be to use a temporary,

size_t my_read(..) {
	size_t x = read(..);
	return x ? x : -1;
}

gcc should be smart enough to also do optimization in the second case..


	Jan
-- 
-
unsubscribe notice
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/