How come C allow structure members to be addressed like an array ?

[pereges]

#include <stdio.h>

typedef struct
{
double x, y, z;
}vector;

int main(void)
{
int i;
vector v;
double *cord;

v.x = 10;
v.y = 1;
v.z = 2;

cord = &v.x;

for(i = 0; i < 3; i++)
{
printf("%f\n", cord[i]);
}
return 0;
}

here's the output i get:
10.000000
1.000000
2.000000

which is the same as v

i don't how it happens as i was just trying some random ideas but
great stuff really. helped me to reduce some of my code to almost
1/3rd its size.

[Antoninus Twink]

On 16 Jun 2008 at 0:34, Keith Thompson wrote:

Stop talking about the "Roma gypsies", right now. Don't respond to
this. Don't try to defend your opinions. Just shut the hell up about
it.

However unpleasant you may find Thomas's racist views, don't you believe
even more strongly that he has a right to free speech?

[santosh]

Antoninus Twink wrote:

On 16 Jun 2008 at 0:34, Keith Thompson wrote:

>Stop talking about the "Roma gypsies", right now. Don't respond to
this. Don't try to defend your opinions. Just shut the hell up
about it.

However unpleasant you may find Thomas's racist views, don't you
believe even more strongly that he has a right to free speech?

Again you fail to understand that there is such a thing called
topicality. Even you must admit that the current subject is simply not
topical in clc. And it's not hair-splitting or pedanticism either. The
subject is *massively* off-topic.

Why not move it to soc.culture.iri sh or somewhere similar?

[vippstar]

On Jun 16, 9:46 pm, santosh <santosh....@gm ail.comwrote:

troll wrote:

<troll snip>

Again you fail to understand that there is such a thing called
topicality. Even you must admit that the current subject is simply not
topical in clc. And it's not hair-splitting or pedanticism either. The
subject is *massively* off-topic.

Why not move it to soc.culture.iri sh or somewhere similar?

santosh, he does understand that. He's a troll, remember? ;-)
Let's just let this thread die peacefully... as you noted such
discussions are massively off-topic, and people can be quite
passionate about them so it's best to just let the topic die.

[Richard Heathfield]

santosh said:

Antoninus Twink wrote:

>On 16 Jun 2008 at 0:34, Keith Thompson wrote:

>>Stop talking about the "Roma gypsies", right now. Don't respond to
this. Don't try to defend your opinions. Just shut the hell up
about it.

However unpleasant you may find Thomas's racist views, don't you
believe even more strongly that he has a right to free speech?

Again you fail to understand that there is such a thing called
topicality. Even you must admit that the current subject is simply not
topical in clc. And it's not hair-splitting or pedanticism either. The
subject is *massively* off-topic.

I agree that it's off-topic. For once I actually agree with Mr Twink, too:
Tomas has the right to peddle his revolting opinions in public if he
wishes. But we are not obliged to listen. And this is supposed to be a
techie group, not a sounding-board for racists.

Why not move it to soc.culture.iri sh or somewhere similar?

I think it would be more appropriate to move it to alt.racist.bigo t, don't
you? But of course, realistically it's way too late to move the discussion
anywhere. There is a certain inertia to a thread, and each new participant
increases that inertia, because it gets harder and harder to get everyone
to agree to subscribe to the new group and continue the thread therein.

--
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

[Richard Tobin]

In article <sl************ *******@nospam. invalid>,
Antoninus Twink <no****@nospam. invalidwrote:

>On 16 Jun 2008 at 0:34, Keith Thompson wrote:

>Stop talking about the "Roma gypsies", right now. Don't respond to
this. Don't try to defend your opinions. Just shut the hell up about
it.

>However unpleasant you may find Thomas's racist views, don't you believe
even more strongly that he has a right to free speech?

How does telling someone not to say something infringe on their right
to free speech?

-- Richard
--
In the selection of the two characters immediately succeeding the numeral 9,
consideration shall be given to their replacement by the graphics 10 and 11 to
facilitate the adoption of the code in the sterling monetary area. (X3.4-1963)

[Mark McIntyre]

Tomás Ó hÉilidhe wrote:

On Jun 16, 10:52 am, Nick Keighley <nick_keighley_ nos...@hotmail. com>
wrote:>

>In my country (UK) you'd have problems with the law for behaving the
way you propose (and a good thing too).

Warning a Roma gypsie to stay out of my personal space is no different
than shouting SHOO at a dog when it comes too close.

That's one racist remark too many. Welcome to my bozo bin.

There isn't a court in Britain or Ireland that would find someone
guilty for punching a Roma gypsie. In fact you'd be hard pushed to
even find a policeman that would pursue the matter.

You appear to be living in the 1970s. Fortunately nowadays in Britain an
unprovoked assault gets prosecuted irrespective of the race of the victim.

[lawrence.jones]

Richard Tobin <ri*****@cogsci .ed.ac.ukwrote:

>
and so it would be unreasonable for the padding of
successive members of the same type in a struct to be different from
that in an array - which is to say, there should be no padding between
fields of the same type.

Can anyone come up with a reason (other than perverseness) why an
implementation would not do this?

Performance. If, for example, word-aligned accesses are more efficient
than non-aligned accesses, an implementation may want to align each
member on at least a word boundary. I know of at least one real
implementation that did, in fact, behave that way. Of course, that
would almost certainly not affect doubles (which tend to have the
strictest alignment requirements anyway), but it might well affect chars
and shorts.

-- Larry Jones

Mom would be a lot more fun if she was a little more gullible. -- Calvin

[pereges]

I think I will use an array and forget about it all together.

typedef struct _vector
{
double coord[3];
}vector;

[Keith Thompson]

pereges <Br*****@gmail. comwrites:

I think I will use an array and forget about it all together.

typedef struct _vector
{
double coord[3];
}vector;

Great. But why use the name "_vector"? If you insist on having
disinct names for the struct tag and the typedef, you could use a
trailing underscore or a "_s" suffix. For that matter, you could
just drop the struct tag:

typedef struct {
double coord[3];
} vector;

(Or you could drop the typedef and just call it "struct vector".)

Names starting with underscores should generally be avoided. I
*think* this one is ok, but the fact that I'm not sure without further
thought is a clue that it's easier just to avoid leading underscores
altogether.

--
Keith Thompson (The_Other_Keit h) ks***@mib.org <http://www.ghoti.net/~kst>
Nokia
"We must do something. This is something. Therefore, we must do this."
-- Antony Jay and Jonathan Lynn, "Yes Minister"

[pereges]

On Jun 17, 3:43 pm, Keith Thompson <[e-mail] rote:

Great. But why use the name "_vector"? If you insist on having
disinct names for the struct tag and the typedef, you could use a
trailing underscore or a "_s" suffix. For that matter, you could
just drop the struct tag:

typedef struct {
double coord[3];
} vector;

The only reason why I do it is because some times I have come across
situations which require self referential structures.

eg.
typedef struct _tree
{
struct _tree *left;
struct _tree *right;
int data;
}tree;

Not that I will always encounter a situation like this, but I just
tried to keep the naming technique consistent.

(Or you could drop the typedef and just call it "struct vector".)

Names starting with underscores should generally be avoided. I
*think* this one is ok, but the fact that I'm not sure without further
thought is a clue that it's easier just to avoid leading underscores
altogether.

Why drop the typedef ? I thought certain expressions would be more
concise.