structure padding

[ramu]

Hi all,
I understand that some compilers pad some bytes to the
aggregate data types in order to access the members of the aggregate
data types(i.e. structure) fast. This depends on the architectures.
Some architectures cannot access the data which will be stored on the
odd addresses or they may find difficult to access it. This is the
reason for padding extra bytes.

Now consider the following structure:

struct {
int i; // 4 bytes
char c; // 1 byte
char b; // 1 byte
}a;

Now consider the memory representation for this structure:

----------------------------- Memory locations
i 0
-----------------------------
i 1
-----------------------------
i 2
------------------------------
i 3
-------------------------------
c 4
--------------------------------
b 5
--------------------------------
padding 6
---------------------------------
padding 7
---------------------------------

The size of this strucutre will be 8bytes after padding.
The first 4 memory locations(0 to 3) are allocated for int i;
The next byte(4) is allocated for char c;
the next byte(5) is allocated for char b;

Now my doubt is , does not the processor find it difficult to access
the value of the variable which is stored in odd memory location(ie.
5)? can anyone elaborate on this?

Regards

[Rod Pemberton]

"CBFalconer " <cb********@yah oo.com> wrote in message
news:43******** *******@yahoo.c om...

Rod Pemberton wrote:

... snip ...

C) It amazes me that there are so many people _here_ who incessantly
whine about things that are _beyond_ their control, like: judgemental
off-topic posts, top posting, cutting reply signatures. The
'perceived constraints' that you experience are _you're_ problem.
Not mine. Honestly, whining about these things reminds me of the
bickering of immature little children. Keep it to yourself and learn
to deal with it.

However the whining bickering immature children often grow up into
useful adults, provided they are corrected when whining, bickering,
or otherwise acting immature. Here we can only identify the
children by their immature actions, such as top-posting, omitting
context, chopping off attributions, failure to snip.

They aren't the ones whining, bickering, and acting immature... You are.
Rod Pemberton

[Rod Pemberton]

"Keith Thompson" <ks***@mib.or g> wrote in message
news:ln******** ****@nuthaus.mi b.org...

"Rod Pemberton" <do*******@bitb ucket.cmm> writes:
[snip]

C) It amazes me that there are so many people _here_ who incessantly whine about things that are _beyond_ their control, like: judgemental off-topic posts, top posting, cutting reply signatures. The 'perceived constraints' that you experience are _you're_ problem. Not mine. Honestly, whining
about these things reminds me of the bickering of immature little children. Keep it to yourself and learn to deal with it.
Um, no.

Um, yes.
There are very good reasons why we try to encourage people to follow
some simple posting guidelines here. Jack Klein did an excellent job
of explaining those reasons.

I don't need to read any of his reasons to know they are totally irrevelant.
You may agree with his statements. But, it doesn't change the fact that you
need to learn accept things the way they are.
Rod Pemberton

[Keith Thompson]

"Rod Pemberton" <do*******@bitb ucket.cmm> writes:

"Keith Thompson" <ks***@mib.or g> wrote in message
news:ln******** ****@nuthaus.mi b.org...

"Rod Pemberton" <do*******@bitb ucket.cmm> writes:
[snip]

> C) It amazes me that there are so many people _here_ who
> incessantly whine about things that are _beyond_ their control,
> like: judgemental off-topic posts, top posting, cutting reply
> signatures. The 'perceived constraints' that you experience are
> _you're_ problem. Not mine. Honestly, whining about these
> things reminds me of the bickering of immature little children.
> Keep it to yourself and learn to deal with it.
Um, no.

Um, yes.

There are very good reasons why we try to encourage people to follow
some simple posting guidelines here. Jack Klein did an excellent job
of explaining those reasons.

I don't need to read any of his reasons to know they are totally
irrevelant.

Yes, you do.
You may agree with his statements. But, it doesn't change the fact that you
need to learn accept things the way they are.

I strongly suggest you read Jack's article anyway. You might or might
not agree, but what he wrote happens to represent the consensus of the
regulars of this newsgroup (trolls excluded). You are, of course,
free to jam your fists into your ears and shout "LALALALALA " until the
bad people stop talking to you.

You make an interesting point about accepting things the way they are.
The same logic implies we should accept spam.

Let me explain to you the way things are. This newsgroup is about
standard C. If you're unwilling to accept that, you will be unable to
participate. Many of the people who happen to know a lot about the
topic will killfile you. I'm sure some of them have already.

If people who know more about this than you do tell you that you're
wrong, you should consider listening to them rather than whining.

--
Keith Thompson (The_Other_Keit h) ks***@mib.org <http://www.ghoti.net/~kst>
San Diego Supercomputer Center <*> <http://users.sdsc.edu/~kst>
We must do something. This is something. Therefore, we must do this.

[Mark McIntyre]

On Fri, 03 Feb 2006 23:39:52 GMT, in comp.lang.c , "Rod Pemberton"
<do*******@bitb ucket.cmm> wrote:

"Keith Thompson" <ks***@mib.or g> wrote in message
news:ln******* *****@nuthaus.m ib.org...

There are very good reasons why we try to encourage people to follow
some simple posting guidelines here. Jack Klein did an excellent job
of explaining those reasons.

I don't need to read any of his reasons to know they are totally irrevelant.

I see. You just don't care. Nice.
You may agree with his statements. But, it doesn't change the fact that you
need to learn accept things the way they are.

There's an alternative - you, yes, you, need to accept things the way
they are in CLC.
Can't handle that? Don't like it? Tough.
Mark McIntyre
--
"Debugging is twice as hard as writing the code in the first place.
Therefore, if you write the code as cleverly as possible, you are,
by definition, not smart enough to debug it."
--Brian Kernighan

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[Default User]

Rod Pemberton wrote:

I don't need to read any of his reasons to know they are totally
irrevelant. You may agree with his statements. But, it doesn't
change the fact that you need to learn accept things the way they are.

*plonk*
Brian

[Rod Pemberton]

"Keith Thompson" <ks***@mib.or g> wrote in message
news:ln******** ****@nuthaus.mi b.org...

"Rod Pemberton" <do*******@bitb ucket.cmm> writes:

"Keith Thompson" <ks***@mib.or g> wrote in message
news:ln******** ****@nuthaus.mi b.org...

"Rod Pemberton" <do*******@bitb ucket.cmm> writes:
[snip]
> C) It amazes me that there are so many people _here_ who
> incessantly whine about things that are _beyond_ their control,
> like: judgemental off-topic posts, top posting, cutting reply
> signatures. The 'perceived constraints' that you experience are
> _you're_ problem. Not mine. Honestly, whining about these
> things reminds me of the bickering of immature little children.
> Keep it to yourself and learn to deal with it.

Um, no.
Um, yes.

There are very good reasons why we try to encourage people to follow
some simple posting guidelines here. Jack Klein did an excellent job
of explaining those reasons.

I don't need to read any of his reasons to know they are totally
irrevelant.

Yes, you do.

You may agree with his statements. But, it doesn't change the fact that you need to learn accept things the way they are.

I strongly suggest you read Jack's article anyway. You might or might
not agree, but what he wrote happens to represent the consensus of the
regulars of this newsgroup (trolls excluded). You are, of course,
free to jam your fists into your ears and shout "LALALALALA " until the
bad people stop talking to you.
You make an interesting point about accepting things the way they are.
The same logic implies we should accept spam.

Let me explain to you the way things are. This newsgroup is about
standard C. If you're unwilling to accept that, you will be unable to
participate. Many of the people who happen to know a lot about the
topic will killfile you. I'm sure some of them have already.

This is comp.lang.c not comp.lang.c.iso or comp.lang.c.ans i or
comp.lang.c.knr ... The point which you seem unable to comprehend is that
_you're_ whining. And, it's irritating people. I know what my IQ is. I
know how in depth my knowledge of C is. And, From my conversations with you
so far, you don't come close to either.
If people who know more about this than you do tell you that you're
wrong, you should consider listening to them rather than whining.

I'm not the one whining. You are. Incessantly, about top-posting,
inlining, google.. Out of the last thirty posts of yours, only one(1) has
contributed anything meaningful to any thread. Only one(1) hasn't been a
complaint. You may think of yourself as a regular, but given your posting
history you are the definition of a _TROLL_. I sincerely hope you aren't
referring to yourself when you mention 'people who know more about this than
you'...

Rod Pemberton

[Flash Gordon]

Rod Pemberton wrote:

"Keith Thompson" <ks***@mib.or g> wrote in message
<snip>

Let me explain to you the way things are. This newsgroup is about
standard C. If you're unwilling to accept that, you will be unable to
participate. Many of the people who happen to know a lot about the
topic will killfile you. I'm sure some of them have already.

This is comp.lang.c not comp.lang.c.iso or comp.lang.c.ans i or
comp.lang.c.knr ...

Yes, it's comp.lang.c, not
comp.lang.c.win dows.and.posix. and.vxworks.and .dos.and.aix.an d.everything.el se.under.the.su n
The point which you seem unable to comprehend is that
_you're_ whining. And, it's irritating people. I know what my IQ is. I
know how in depth my knowledge of C is. And, From my conversations with you
so far, you don't come close to either.

My impression having seen Keith's posts since I've been on the group is
that he is highly knowledgeable and an intelligent chap.

You come across as the person whining about the group not being what you
want it to be.

If people who know more about this than you do tell you that you're
wrong, you should consider listening to them rather than whining.

I'm not the one whining. You are. Incessantly, about top-posting,
inlining, google.. Out of the last thirty posts of yours, only one(1) has
contributed anything meaningful to any thread. Only one(1) hasn't been a
complaint. You may think of yourself as a regular, but given your posting
history you are the definition of a _TROLL_. I sincerely hope you aren't
referring to yourself when you mention 'people who know more about this than
you'...

I believe the people Keith is referring to include members of the
standard committee, authors of successful C implementations (or parts
their of) and authors of successful books on C. Keith and the others
that correct peoples posting style also provide a lot of useful content
(I attempt to fall in to that category as well).

If you don't like the attitude of the regulars or the limits on what the
regulars consider to be topical, feel free to find yourself another group.
--
Flash Gordon
Living in interesting times.
Although my email address says spam, it is real and I read it.

[Mark McIntyre]

On Sat, 04 Feb 2006 04:39:49 GMT, in comp.lang.c , "Rod Pemberton"
<do*******@bitb ucket.cmm> wrote:

This is comp.lang.c not comp.lang.c.iso or comp.lang.c.ans i or
comp.lang.c.kn r...
Correct. and hte topic of comp.lang.c is use of the C Language as
defined by ISO.
The point which you seem unable to comprehend is that
_you're_ whining. And, it's irritating people.
Wrong on both counts.

The point *you* seem unable to comprehend is that the topic of this
group is not Windows, nor unix, nor databases, nor TCPIP.

It doesn't matter that you can link your C code with libraries to
access these things, you can similarly do it from Fortran, Basic,
perl, python, and for all I know Haskell. These services are *not part
of C* and are therefore offtopic.
I know what my IQ is. I
know how in depth my knowledge of C is. And, From my conversations with you
so far, you don't come close to either.

I agree. It will be many decades before you can climb up to Keith's
level on either front, and meantime you'll need to learn some
humility.

Mark McIntyre
--
"Debugging is twice as hard as writing the code in the first place.
Therefore, if you write the code as cleverly as possible, you are,
by definition, not smart enough to debug it."
--Brian Kernighan

----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet News==----
http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups
----= East and West-Coast Server Farms - Total Privacy via Encryption =----

[Jordan Abel]

On 2006-02-04, Mark McIntyre <ma**********@s pamcop.net> wrote:

On Sat, 04 Feb 2006 04:39:49 GMT, in comp.lang.c , "Rod Pemberton"
<do*******@bitb ucket.cmm> wrote:

This is comp.lang.c not comp.lang.c.iso or comp.lang.c.ans i or
comp.lang.c.k nr...

Correct. and hte topic of comp.lang.c is use of the C Language as
defined by ISO.

Or as defined by ANSI in the 80s, or as defined by K&R in the 70s.

Not, of course, as defined by Microsoft, or Borland, or GNU.