about structures memory allocation

[bharath539]

how much memory is allocated for following structure
struct bharath
{
int b;
char c;
float d;
}

and how?

[Clever Monkey]

bh********@gmai l.com wrote:

how much memory is allocated for following structure
struct bharath
{
int b;
char c;
float d;
}

and how?

Enough to fit at least the total memory requirements of the struct.
Since the primitive types in the struct can vary in width from platform
to platform and implementation to implementation (except char, of
course) the size of the struct will also vary.

How do you do it, or how is memory allocated at runtime? The former is
just allocating for any type, really. If the latter, this is likely
implementation specific, at least based on my lurking in this newsgroup,
and my (poor) knowledge of the Standard.
--
clvrmnky <mailto:sp***** *@clevermonkey. org>

Direct replies will be blacklisted. Replace "spamtrap" with my name to
contact me directly.

[Richard Heathfield]

bh********@gmai l.com said:

how much memory is allocated for following structure
struct bharath
{
int b;
char c;
float d;
}

None. It's a type, not an object.

--
Richard Heathfield
"Usenet is a strange place" - dmr 29/7/1999
http://www.cpax.org.uk
email: rjh at the above domain, - www.

[balu]

On Jun 21, 7:33 pm, Richard Heathfield <[e-mail].i nvalidwrote:

bharath...@gmai l.com said:

how much memory is allocated for following structure
struct bharath
{
int b;
char c;
float d;
}

None. It's a type, not an object.

--
Richard Heathfield
"Usenet is a strange place" - dmr 29/7/1999http://www.cpax.org.uk
email: rjh at the above domain, - www.

let the int size is 4B then the allocation will be?
i want to know the info regarding padding or some other else related
to padding?

[Chris Dollin]

bh********@gmai l.com wrote:

how much memory is allocated for following structure
struct bharath
{
int b;
char c;
float d;
}

and how?

Objects of that type will have enough memory allocated to hold an
int, a char, a float (in that order), plus any necessary padding.

The details vary with the implementation -- which may include the
option settings for your compilation(s).

If you want to know how much has /actually/ been allocated, use
`sizeof (struct bharath)`.

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

[Clever Monkey]

balu wrote:

On Jun 21, 7:33 pm, Richard Heathfield <[e-mail].i nvalidwrote:

>bharath...@gma il.com said:

>>how much memory is allocated for following structure
struct bharath
{
int b;
char c;
float d;
}

None. It's a type, not an object.

[Please use a newsreader that understands how to trim sigs, or trim them
yourself. I've done this for you here.]

let the int size is 4B then the allocation will be?
i want to know the info regarding padding or some other else related
to padding?

This is exactly the sort of thing that people talk about when they say
something is implementation specific. That is, once you actually
allocate for a type, the specifics of how that memory is allocated is
not necessarily dictated by the Standard.

Simply defining (or is it declaring?) the type, of course, allocates no
memory.
--
clvrmnky <mailto:sp***** *@clevermonkey. org>

Direct replies will be blacklisted. Replace "spamtrap" with my name to
contact me directly.

[bharath539]

On Jun 21, 7:49 pm, Clever Monkey <spamt...@cleve rmonkey.org.INV ALID>
wrote:

balu wrote:

On Jun 21, 7:33 pm, Richard Heathfield <[e-mail].i nvalidwrote:

bharath...@gmai l.com said:

>how much memory is allocated for following structure
struct bharath
{
int b;
char c;
float d;
}
None. It's a type, not an object.

[Please use a newsreader that understands how to trim sigs, or trim them
yourself. I've done this for you here.]

let the int size is 4B then the allocation will be?
i want to know the info regarding padding or some other else related
to padding?

This is exactly the sort of thing that people talk about when they say
something is implementation specific. That is, once you actually
allocate for a type, the specifics of how that memory is allocated is
not necessarily dictated by the Standard.

Simply defining (or is it declaring?) the type, of course, allocates no
memory.
--
clvrmnky <mailto:spamt.. .@clevermonkey. org>

Direct replies will be blacklisted. Replace "spamtrap" with my name to
contact me directly.

what i want actually is how much size will be allocated for above
structuer in a 16 bit machine

[Lew Pitcher]

On Jun 21, 10:56 am, "bharath...@gma il.com" <bharath...@gma il.com>
wrote:

On Jun 21, 7:49 pm, Clever Monkey <spamt...@cleve rmonkey.org.INV ALID>
wrote:

balu wrote:

On Jun 21, 7:33 pm, Richard Heathfield <[e-mail].i nvalidwrote:
>bharath...@gma il.com said:

>>how much memory is allocated for following structure
>> struct bharath
>> {
>> int b;
>> char c;
>> float d;
>> }
>None. It's a type, not an object.

[Please use a newsreader that understands how to trim sigs, or trim them
yourself. I've done this for you here.]

let the int size is 4B then the allocation will be?
i want to know the info regarding padding or some other else related
to padding?

This is exactly the sort of thing that people talk about when they say
something is implementation specific. That is, once you actually
allocate for a type, the specifics of how that memory is allocated is
not necessarily dictated by the Standard.

Simply defining (or is it declaring?) the type, of course, allocates no
memory.
--
clvrmnky <mailto:spamt.. .@clevermonkey. org>

Direct replies will be blacklisted. Replace "spamtrap" with my name to
contact me directly.

what i want actually is how much size will be allocated for above
structuer in a 16 bit machine

Here's the exact answer for you: your program will allocate
sizeof(struct bharath) bytes. Other than that, we cannot tell you, as
the exact number of bytes depends on the compiler, the operating
system, and the processor.

What we can tell you is that there may be padding characters inserted
between each element of the structure to maintain data item alignment.
If, *for instance*, ints were 4 bytes wide, and floats were 8 bytes
wide, and both were required to be aligned on "even" boundaries (ints
to &int%4==0 boundaries, floats to &float%8==0 boundaries), then the
compiler would likely insert zero padding bytes between your int and
your char, and seven padding bytes between your char and your float.

[Lew Pitcher]

Oops... a correction

On Jun 21, 11:09 am, Lew Pitcher <lpitc...@teksa vvy.comwrote:
[snip]

What we can tell you is that there may be padding characters inserted
between each element of the structure to maintain data item alignment.
If, *for instance*, ints were 4 bytes wide, and floats were 8 bytes
wide, and both were required to be aligned on "even" boundaries (ints
to &int%4==0 boundaries, floats to &float%8==0 boundaries), then the
compiler would likely insert zero padding bytes between your int and
your char, and seven padding bytes

make that three padding bytes

between your char and your float.

[Clever Monkey]

bh********@gmai l.com wrote:

On Jun 21, 7:49 pm, Clever Monkey <spamt...@cleve rmonkey.org.INV ALID>
wrote:

>balu wrote:

>>On Jun 21, 7:33 pm, Richard Heathfield <[e-mail].i nvalidwrote:
bharath...@g mail.com said:
how much memory is allocated for following structure
struct bharath
{
int b;
char c;
float d;
}
None. It's a type, not an object.

[...]
*sigh*

>>let the int size is 4B then the allocation will be?
i want to know the info regarding padding or some other else related
to padding?

This is exactly the sort of thing that people talk about when they say
something is implementation specific. That is, once you actually
allocate for a type, the specifics of how that memory is allocated is
not necessarily dictated by the Standard.

Simply defining (or is it declaring?) the type, of course, allocates no
memory.

[...]
*double sigh*

what i want actually is how much size will be allocated for above
structuer in a 16 bit machine

Enough to hold the structure, plus any padding, on this specific 16-bit
machine.

Folks here are not being coy. There is no way to know, in general, how
your compiler will allocate space, even if we know something about it or
the platform is is generating code for. (Like it happens to be a
"16-bit" machine, whatever that is. How are those bits represented?)

If you have a specific implementation in mind, on a specific platform,
then someone with the knowledge and access to the documentation could
tell you with more detail.

This very quality of C is why the compiler has been successfully
targeted to a great many platforms, and why standard code is relatively
easy to port.
--
clvrmnky <mailto:sp***** *@clevermonkey. org>

Direct replies will be blacklisted. Replace "spamtrap" with my name to
contact me directly.