How to determine the size of dynamical arrays?

[FraterQ]

Hello,

after i've read this post, i tried it myself and it works.
http://groups.google.com/groups?hl=e...oogle%2BSearch
But I've the following problem: I can't determine the size of the
dynamical generated array through a predefined function like sizeof().
Can anybody explain, how to get the reserved memorysize?

Thanks,
Frater

[Tom St Denis]

FraterQ wrote:

Hello,

after i've read this post, i tried it myself and it works.
http://groups.google.com/groups?hl=e...oogle%2BSearch
But I've the following problem: I can't determine the size of the
dynamical generated array through a predefined function like sizeof().
Can anybody explain, how to get the reserved memorysize?

"dynamical" ???

This question is asked far too often. Go read the FAQ.

Tom

[Richard Heathfield]

FraterQ wrote:

<snip>

But I've the following problem: I can't determine the size of the
dynamical generated array through a predefined function like sizeof().
Can anybody explain, how to get the reserved memorysize?

When you allocate the memory, you know how much you're allocating.

Don't Forget.

--
Richard Heathfield : bi****@eton.pow ernet.co.uk
"Usenet is a strange place." - Dennis M Ritchie, 29 July 1999.
C FAQ: http://www.eskimo.com/~scs/C-faq/top.html
K&R answers, C books, etc: http://users.powernet.co.uk/eton

[Emmanuel Delahaye]

In 'comp.lang.c', [e-mail] (FraterQ) wrote:

Hello,

after i've read this post, i tried it myself and it works.
http://groups.google.com/groups?hl=e...&threadm=9jjh9
m%247bb%242%40o ravannahka.hels inki.fi&rnum=1& prev=/groups%3Fhl%3De n%26lr%
3D%26ie%3DUTF-8%26oe%3Dutf-8%26q%3Dresize% 2Barray%2Bc%2Br ealloc%26btnG%3 D
Google%2BSearch But I've the following problem: I can't determine the
size of the dynamical generated array through a predefined function like
sizeof(). Can anybody explain, how to get the reserved memorysize?

Ask the one who has allocated the memory block to keep the size in some
memory. A common tip is the following :

typedef struct
{
int *a; /* dynamic array of int */
size_t n;
}
buf_s;

buf_s buf;

buf_create (&buf, 123);

with

int buf_create (buf_s * this, size_t n)
{
err = 1;

if (this)
{
this->a = NULL;
this->n = 0;

{
int *p = malloc (sizeof *p * n); /* <stdlib.h> */

if (p)
{
this->a = p;
this->n = n;
err = 0;
}
}
}
return err;
}
--
-ed- em**********@no os.fr [remove YOURBRA before answering me]
The C-language FAQ: http://www.eskimo.com/~scs/C-faq/top.html
<blank line>
FAQ de f.c.l.c : http://www.isty-info.uvsq.fr/~rumeau/fclc/

[Martin Ambuhl]

[e-mail] (FraterQ) wrote (02 Jul 2003) in
news:56******** *************** ***@posting.goo gle.com / comp.lang.c:

Hello,

after i've read this post, i tried it myself and it works.
http://groups.google.com/groups?hl=e...=utf-8&threadm
=9jjh9m%247bb%2 42%40oravannahk a.helsinki.fi&r num=1&prev=/groups%3Fh
l%3Den%26lr%3D% 26ie%3DUTF-8%26oe%3Dutf-8%26q%3Dresize% 2Barray%2Bc%2
Brealloc%26btnG %3DGoogle%2BSea rch But I've the following problem:
I can't determine the size of the dynamical generated array
through a predefined function like sizeof(). Can anybody explain,
how to get the reserved memorysize?

Remember it, for goodness' sake! You can't dynamically create
without having the size information; why do you throw away what you
already know?
--
Martin Ambuhl
Returning soon to the
Fourth Largest City in America