C objects

[junky_fellow]

What is a C object ?

If i have some function "func()" in my C program, then
can i say that "func()" is a C object ?
or if i have some function pointer (ptr) which contains the address
of function "func()", can i say that ptr is pointing to some C object ?

Is a C object always associated with some "data" ?

thanx in advance for any help .....

[pete]

E. Robert Tisdale wrote:

struct X {
int* p;
};

struct X x;

Does the object referenced through x include
the region of data pointer to by p?

No.
x is an object of type struct X.
(sizeof x) is not affected by what x.p points to.
Objects are blocks of contiguous memory.
It's explicitly stated in the C89 object definition.

C89 Last public draft
1.6 DEFINITIONS OF TERMS
* Object --- a region of data storage in the execution environment,
the contents of which can represent values. Except for bit-fields,
objects are composed of contiguous sequences of one or more bytes,
the number, order, and encoding of which are either explicitly
specified or implementation-defined.

A list is not an object.

--
pete

[junky_fellow]

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

"E. Robert Tisdale" <E.************ **@jpl.nasa.gov > writes:

Keith Thompson wrote:

E. Robert Tisdale writes:
> The type defines
> *all* of the values that an object of that type may have
> so an object *must* be initialized to one of those values
> if it is to be called an object of that type.

Perhaps, but it doesn't have to be initialized to be called an object.
An object is a "region of data storage in the execution environment,
the contents of which can represent values" (C99 3.14).

And, of course, the term "object" as used in C
has nothing at all to do with object-oriented programming.

[Humpty Dumpty quotation deleted'

What do you think the term 'object" means
in the phrase 'object-oriented programming'?

I don't have a good answer to that. All I can say (and all I care to
say) is that the usual meaning of "object" in the context of
object-oriented programming is different from the definition in the C
standard (C99 3.14):

region of data storage in the execution environment, the contents
of which can represent values

NOTE When referenced, an object may be interpreted as having a
particular type; see 6.3.2.1.

(The note is not part of the definition.)

The C90 definition is more verbose (C90 3.14), but it expresses the
same basic idea:

A region of data storage in the execution environment, the
contents of which can represent values. Except for
bit-fields, objects are composed of contiguous sequences of one or
more bytes, the number, order, and encoding of which are either
explicitly specified or implementation-defined. When referenced,
an object may be interpreted as having a particular type, see
6.2.2

(That may not be an exact quote; my copy of the C90 standard makes
cut-and-paste difficult.)

Are you saying that it is not possible
to write object-oriented programs in C?

No, I'm not saying that, nor have I ever said anything resembling it.
Why do you ask?

Why not say 'region of data storage' instead of object
if that is all that is meant by object?

What I am saying is that the English language is badly abused
in the standards documents.
It converts ordinary English words into meaningless jargon.
These redefinitions narrow the meaning of these words
to the point where it is impossible to make valid inferences
and require the redefinition of other common terms.

No, it converts ordinary English words into meaningful jargon. Any
field of discourse has its own jargon, consisting of ordinary words
with specific definitions, phrases, and, in some cases, invented
words. (The word "object" in everyday English has a meaning that's
not particularly useful in the context of programming languages, for
example.)

If you're going to discuss C, as you insist on doing, you have to
understand the way the C standard defines certain terms. If you're
going to use terms defined in the C standard in ways inconsistent with
their definitions, you're going to have difficulties communicating in
this newsgroup (as you've already discovered).

For example, your redefinition of object appears to require
the redefinition of the term type
to include *all* of the values that could be represented
by the "region of storage" that you call a type.

It's not *my* redefinition, it's in the C standard. Apart from that,
I'm not sure what you mean.

This, in turn, seems to imply that the type depends
upon the representation that the programmer chooses
and that data abstraction is impossible in C.

Nonsense.

Take for example

struct X {
int* p;
};

struct X x;

Does the object referenced through x include
the region of data pointer to by p?

Given the C standard's definition of "object", the object named x
includes the storage for x.p, but it doesn't include the region of
data pointed to by x.p. If you want to refer to both x and the data
pointed to by x.p as a single entity, you should choose a name other
than "object"; I suggest "data structure".

So, can we say a function pointer to be an object ?

[Mabden]

"junky_fell ow" <ju**********@y ahoo.co.in> wrote in message
news:8c******** *************** ***@posting.goo gle.com...

So, can we say a function pointer to be an object ?

Not in English.

[Keith Thompson]

ju**********@ya hoo.co.in (junky_fellow) writes:
[...]

So, can we say a function pointer to be an object ?

Yes. (BTW, please trim any quoted text that's not relevant to your
question.)

--
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.

[E. Robert Tisdale]

junky_fellow wrote:

So, can we say a function pointer to be an object?

A function is an object.
A pointer to that function is another object.

[Joe Wright]

E. Robert Tisdale wrote:

junky_fellow wrote:

So, can we say a function pointer to be an object?

A function is an object.
A pointer to that function is another object.

Pray tell where you find a function described as an object in C.
--
Joe Wright mailto:jo****** **@comcast.net
"Everything should be made as simple as possible, but not simpler."
--- Albert Einstein ---

[E. Robert Tisdale]

Joe Wright wrote:

E. Robert Tisdale wrote:

A function is an object.
A pointer to that function is another object.

Pray tell where you find a function described as an object in C.

I used Google

http://www.google.com/

to search for

+"functions are objects" +"C programming"

[Arthur J. O'Dwyer]

On Sat, 14 Aug 2004, E. Robert Tisdale wrote:

E. Robert Tisdale wrote:

A function is an object.
A pointer to that function is another object.

For the record: Functions are /not/ objects in C. However,
pointers are objects, be they pointers to functions or pointers
to data.

(It's been a while since the last blatant troll of Tisdale's,
so I expect we have a crop of newbies who might assume Tisdale
wasn't being maliciously wrong in his statements. FYI, he's a
well-known regular in c.l.c---please just ignore his ravings.)

-Arthur

[Flash Gordon]

On Sat, 14 Aug 2004 13:48:19 -0700
"E. Robert Tisdale" <E.************ **@jpl.nasa.gov > wrote:

junky_fellow wrote:

So, can we say a function pointer to be an object?
A function is an object.

Not according to the C standard according to what the more knowledgeable
people around here have said.
A pointer to that function is another object.

Yes, a pointer to a function is an object.
--
Flash Gordon
Sometimes I think shooting would be far too good for some people.
Although my email address says spam, it is real and I read it.

[E. Robert Tisdale]

Something that calls itself Flash Gordon wrote:

E. Robert Tisdale wrote:

A function is an object.

Not according to the C standard according to what the more knowledgeable
people around here have said.

You are confused.
The C standards documents are *not*
part of the C computer programming language.
There is no 'object' keyword os standard identifier
in the C computer programming language.
The C standards documents have *nothing* to do with programming in C.
They exist *only* to specify the C computer programming language.
Terms, like object, given special meaning in the standards documents
to help with these specifications,
have *no* meaning outside of the scope of the standards documents
other that those meanings commonly used
in the context of a computer programming language.

Questions (remarks) about the C standards are off-topic in comp.lang.c
There is a more appropriate form for that -- comp.std.c

Please direct all your questions (remarks)
about the C standards documents to the appropriate newsgroup.