Where is a static variable stored?

[Jack]

Thanks.

[Keith Thompson]

"Jack" <ju******@gmail .comwrites:

Thanks.

Please put the question in the body of your article. Not all
newsreaders display the subject along with the body.

The subject was: "Where is a static variable stored?".

The answer: In memory. A variable of static storage duration must be
available throughout the lifetime of the program. The C standard
doesn't require any specific method of making this happen, and
different compilers can do it differently.

If you want to know how some particular compiler does this, you'll
need to consult your compiler's documentation or ask in a
compiler-specific or system-specific newsgroup -- but any code you
write that depends on this information will be non-portable, and
probably needlessly so.

--
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.

[Michael Mair]

Jack schrieb:

Thanks.

You're welcome.

Please write/repeat your question in the message text -- there
are newsreaders which do not show subject and message text at
the same time.

Your question: "Where is a static variable stored?" has no
standard C answer.
Variables with static storage duration "live" throughout the
programme's lifetime. Whether they are stored all or only part
of the time in RAM, ROM, or registers is not specified -- they
have only to behave as if they were there the whole time.

This may not be the answer to what you _wanted_ to ask; please
be precise in your questions.
Cheers
Michael
--
E-Mail: Mine is an /at/ gmx /dot/ de address.

[Jack]

Michael Mair wrote:

Jack schrieb:

Thanks.

You're welcome.

Please write/repeat your question in the message text -- there
are newsreaders which do not show subject and message text at
the same time.

Your question: "Where is a static variable stored?" has no
standard C answer.
Variables with static storage duration "live" throughout the
programme's lifetime. Whether they are stored all or only part
of the time in RAM, ROM, or registers is not specified -- they
have only to behave as if they were there the whole time.

This may not be the answer to what you _wanted_ to ask; please
be precise in your questions.
Cheers
Michael
--
E-Mail: Mine is an /at/ gmx /dot/ de address.

Thanks. Is a static variable stored at heap or stack?

Jack

[Ian Collins]

Jack wrote:

Michael Mair wrote:

>>Jack schrieb:

>>>Thanks.

You're welcome.

Please write/repeat your question in the message text -- there
are newsreaders which do not show subject and message text at
the same time.

Your question: "Where is a static variable stored?" has no
standard C answer.
Variables with static storage duration "live" throughout the
programme's lifetime. Whether they are stored all or only part
of the time in RAM, ROM, or registers is not specified -- they
have only to behave as if they were there the whole time.

This may not be the answer to what you _wanted_ to ask; please
be precise in your questions.
Cheers
Michael
--
E-Mail: Mine is an /at/ gmx /dot/ de address.

Thanks. Is a static variable stored at heap or stack?

Jack

Please don't quote signatures.

If your implementation is a typical managed one that uses heap and
stack, static variables won't be on either.

They will be stored somewhere else in the program's address space,
frequently another memory segment.

But there isn't a standard answer.

--
Ian Collins.

[Alf P. Steinbach]

* Jack:

>
Thanks. Is a static variable stored at heap or stack?

Heap and stack are (in this context) two memory management schemes: ways
to allocate and deallocate memory. They are not, necessarily, two areas
of memory, and furthermore the C language standard probably does not use
the terms heap and stack. For a given C implementation it may be the
case that there is an area of memory used for stack allocation (last
allocated first deallocated), and an area of memory used for heap
allocation (arbitrary order of allocation and deallocation), and if so
it's highly unlikely, but not impossible, that a static variable resides
in one of these memory areas; what you do know is what's already been
explained in this thread about the /lifetime/ of a static variable.

--
A: Because it messes up the order in which people normally read text.
Q: Why is it such a bad thing?
A: Top-posting.
Q: What is the most annoying thing on usenet and in e-mail?

[Peter Nilsson]

Jack wrote:

Michael Mair wrote:

...
Your question: "Where is a static variable stored?" has no
standard C answer.
Variables with static storage duration "live" throughout the
programme's lifetime. Whether they are stored all or only part
of the time in RAM, ROM, or registers is not specified -- they
have only to behave as if they were there the whole time.

Thanks. Is a static variable stored at heap or stack?

Quite a number of newbies fall into the trap of thinking that _where_
is more important than _when_ when it comes to object storage.
You appear to be one of them.

The standard says nothing about where, it only says when. That's
all the vast majority of C programs ever need to know.

--
Peter

[Gordon Burditt]

>Thanks. Is a static variable stored at heap or stack?

On many implementations , NO.

Heap: that place from which dynamically allocated memory (from
malloc() and friends) is allocated.
Stack: that place from which auto variables are allocated, even
if there is no hardware stack.

"heap" and "stack" need not be mutually exclusive, using the above
definitions.

Gordon L. Burditt

[Keith Thompson]

"Jack" <ju******@gmail .comwrites:
[...]

Thanks. Is a static variable stored at heap or stack?

Jack

Probably not.

Why do you care? If you're just trying to understand how things are
implemented, that's great (and you need to be aware, in this case,
that the language specifies lifetime, not mechanism).

A static variable is stored in memory. It's available throughout the
lifetime of your program, and it has an address that does not vary
during the execution of your program (though it can vary from one
execution to the next). That's really all you need to know.

Well, maybe not. Some systems impose limits on certain memory regions
(stack size, data size, etc), and knowing what's stored where can be
helpful if you're trying to avoid running into those limits.

Tell us what you're really trying to do, and we can probably help you
do it. I suspect you're making some implicit assumptions; without
knowing what those assumptions are, we can't be very helpful.

--
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.

[jjf]

Jack wrote:

>
Thanks. Is a static variable stored at heap or stack?

Possibly, or possibly somewhere else. Why do you care? C doesn't
specify where they are stored. Every compiler could store them
somewhere different, or even store different static variables in a
single program in different ways if it chose to.

If you have a good reason to care, you'll have to check with someone
who knows how your compiler works in the circumstances in which you're
using it - either that, or look at the code it has produced and work it
out from there. Bear in mind that it may not do it that way next time,
and other compilers may not do it that way.