«

what's this?

> Is that sufficiently simple for you? (Remember to replace 11 with a
> different
> value from the array if sizeof(float) doesn't happen to be 3 on your
> system.)

Does something like this have a legitimate use at all?

MisterE wrote:

>
>
>> Is that sufficiently simple for you? (Remember to replace 11 with a
>> different
>> value from the array if sizeof(float) doesn't happen to be 3 on your
>> system.)
>
> Does something like this have a legitimate use at all?

/Something/ like this, yes, depending on how close a similarity
you insist on. `malloc` is, after all, a useful function.

--
"Never ask that question!" /Babylon 5/

Hewlett-Packard Limited Cain Road, Bracknell, registered no:
registered office: Berks RG12 1HN 690597 England

"MisterE" <> writes:

>> Is that sufficiently simple for you? (Remember to replace 11 with a
>> different
>> value from the array if sizeof(float) doesn't happen to be 3 on your
>> system.)
>
> Does something like this have a legitimate use at all?

This may save you a couple of bytes.

Making it more readable by placing the table as a static before the
call would probably not cost you any bytes, this would, however only
work if this is used where you can have declarations, otherwise eg. in
a macro, this may be a solution.

The numbers look odd though, appearently only size 1 to 4 produces
sensible values, what's the context here?

--
... __o Øyvind
... _`\(, http://www.darkside.no/olr/
... (_)/(_) ... biciclare necesse est ...

fuzhen wrote:
> what's this?
Doodles from a sick programmer.

"fuzhen" <> schreef in bericht
news:b4f91191-dafe-4a63-84a7-...
> what's this?

in what context was this used?

On Jun 11, 4:30 pm, Richard Heathfield <r...@see.sig.invalid> wrote:
> fuzhen said:
>
> > what's this?
>
> Checking the subject line, I guess you are referring to this:
>
> p=(char *)malloc((sizeof(float))["\000\006\010\013\015\100"])
>
> to which the answer is that it's a badly written call to malloc. But, given
> suitable furniture (a function wrapped around it, <stdlib.h>, etc - and a
> semicolon wouldn't go amiss at the end there), it's perfectly legal, provided
> sizeof(float) doesn't exceed 6 on the target system. On systems where it
> does, the behaviour is undefined.
>
> Let's start off by assuming sizeof(float) is 3 - which is a perfectly legal
> value for sizeof(float), and has the merit of being a little unlikely, to say
> the least.
>
> Thus, given that assumption, the code reduces to:
>
> p=(char *)malloc((3)["\000\006\010\013\015\100"])
>
> and (3) is just 3, so that gives us:
>
> p=(char *)malloc(3["\000\006\010\013\015\100"])
>
> Now, a[i] and *(a + i) are guaranteed to be equivalent, so let's do some
> substituting:
>
> p=(char *)malloc(*(3+"\000\006\010\013\015\100"))
>
> Okay, x+y is the same as y+x, so:
>
> p=(char *)malloc(*("\000\006\010\013\015\100"+3))
>
> and *(a + i) is the same as a[i], so:
>
> p=(char *)malloc("\000\006\010\013\015\100"[3])
>
> Now, "\000\006\010\013\015\100" is an array with values { 0, 6, 8, 11, 13, 64,
> 0 }, so "\000\006\010\013\015\100"[3] is element 3 of that array: element 0
> is 0, element 1 is 6, element 2 is 8, element 3 is 11. So we can substitute
> that back in again:
>
> p=(char *)malloc(11)
>
> and finally we can lose the spurious and utterly pointless cast, which gives:
>
> p = malloc(11)
>
> Is that sufficiently simple for you? (Remember to replace 11 with a different
> value from the array if sizeof(float) doesn't happen to be 3 on your system.)
>
> --
> Richard Heathfield <http://www.cpax.org.uk>
> Email: -http://www. +rjh@
> Google users: <http://www.cpax.org.uk/prg/writings/googly.php>
> "Usenet is a strange place" - dmr 29 July 1999

This is the first time I am seeing array literals declared in this
manner. This is a new addition in C99, isn't it? And this cryptic
thing is supposed to pass array literals ( just to quote one of the
possible scenarios).

rahul wrote:
> Richard Heathfield <r...@see.sig.invalid> wrote:
> > Checking the subject line, I guess you are referring to this:
> >
> > p=(char *)malloc((sizeof(float))["\000\006\010\013\015\100"])
<snip>
>
> This is the first time I am seeing array literals declared in this
> manner. This is a new addition in C99, isn't it?

No. Neither string literals nor a[i] == i[a] is new.

--
Peter

On Jun 12, 10:07 am, Peter Nilsson <ai...@acay.com.au> wrote:
> rahul wrote:
> > Richard Heathfield <r...@see.sig.invalid> wrote:
> > > Checking the subject line, I guess you are referring to this:
>
> > > p=(char *)malloc((sizeof(float))["\000\006\010\013\015\100"])
> <snip>
>
> > This is the first time I am seeing array literals declared in this
> > manner. This is a new addition in C99, isn't it?
>
> No. Neither string literals nor a[i] == i[a] is new.
>
> --
> Peter

Thanks Peter,
I missed that part in the FAQ. I got my answer.
char *a = "hello";
printf ("%c", 2[a]);
The above snippet directly does
printf ("%c", 2["hello"]);

a[i] == i[a]. Hey...I knew that