regarding size_t

[sam_cit]

Hi Everyone,

I was looking at the function prototype of malloc() function in
stdlib.h and i found that to be,

void *malloc(size_t size);

so what is size_t is it a pre-defined typedef to int?

Thanks in advance.

[jaysome]

On 13 Jan 2007 01:39:22 -0800, sa*****@yahoo.c o.in wrote:

>Hi Everyone,

I was looking at the function prototype of malloc() function in
stdlib.h and i found that to be,

void *malloc(size_t size);

so what is size_t is it a pre-defined typedef to int?

Thanks in advance.

size_t is a pre-defined type, which, according to the C Standard, is
"the unsigned integral type of the result of the sizeof operator". The
type size_t is unsigned, and it cannot possibly be defined as type
int, which must be signed.

--
jay

[=?utf-8?B?SGFyYWxkIHZhbiBExLNr?=]

sam_...@yahoo.c o.in wrote:

Hi Everyone,

I was looking at the function prototype of malloc() function in
stdlib.h and i found that to be,

void *malloc(size_t size);

so what is size_t is it a pre-defined typedef to int?

size_t is a typedef for some unsigned integer type meant to be capable
of storing the size of objects. It is not pre-defined: it is defined in
several of the standard headers, but if you don't include any of them,
you're free to use size_t as an ordinary identifier in your own code.
Which specific type it has depends on the implementation, and it would
be best not to assume anything more than you need to about it.

[CBFalconer]

Harald van D?k wrote:

sam_...@yahoo.c o.in wrote:

>I was looking at the function prototype of malloc() function in
stdlib.h and i found that to be,

void *malloc(size_t size);

so what is size_t is it a pre-defined typedef to int?

size_t is a typedef for some unsigned integer type meant to be
capable of storing the size of objects. It is not pre-defined: it
is defined in several of the standard headers, but if you don't
include any of them, you're free to use size_t as an ordinary
identifier in your own code. Which specific type it has depends
on the implementation, and it would be best not to assume
anything more than you need to about it.

No, you are not free to use it for other purposes. You MAY get
away with it on some implementations . You are not free to use
anything defined in any standard headers.

--
"The most amazing achievement of the computer software industry
is its continuing cancellation of the steady and staggering
gains made by the computer hardware industry..." - Petroski

[=?utf-8?B?SGFyYWxkIHZhbiBExLNr?=]

CBFalconer wrote:

Harald van D?k wrote:

sam_...@yahoo.c o.in wrote:

I was looking at the function prototype of malloc() function in
stdlib.h and i found that to be,

void *malloc(size_t size);

so what is size_t is it a pre-defined typedef to int?

size_t is a typedef for some unsigned integer type meant to be
capable of storing the size of objects. It is not pre-defined: it
is defined in several of the standard headers, but if you don't
include any of them, you're free to use size_t as an ordinary
identifier in your own code. Which specific type it has depends
on the implementation, and it would be best not to assume
anything more than you need to about it.

No, you are not free to use it for other purposes. You MAY get
away with it on some implementations . You are not free to use
anything defined in any standard headers.

Citation, please?

[Eric Sosman]

jaysome wrote:

On 13 Jan 2007 01:39:22 -0800, sa*****@yahoo.c o.in wrote:

>Hi Everyone,

I was looking at the function prototype of malloc() function in
stdlib.h and i found that to be,

void *malloc(size_t size);

so what is size_t is it a pre-defined typedef to int?

Thanks in advance.

size_t is a pre-defined type, which, according to the C Standard, is
"the unsigned integral type of the result of the sizeof operator". The
type size_t is unsigned, and it cannot possibly be defined as type
int, which must be signed.

A minor clarification: size_t is "pre-defined" if you include
one or more of the headers that define it, but is not "baked in"
to the compiler in the way sizeof is. The following is a legal C
function, albeit a stupid one:

#include <math.h>
double size_t(double FILE, double NULL, double offsetof) {
return (-NULL + sqrt(NULL*NULL - 4*FILE*offsetof ))
/ (2*FILE);
}

The following translation unit is not legal C:

/* no header inclusions */
size_t elementCount(si ze_t arraySize, size_t elementSize) {
return arraySize / elementSize;
}

.... because size_t is not defined.

--
Eric Sosman
es*****@acm-dot-org.invalid

[Martin Ambuhl]

sa*****@yahoo.c o.in wrote:

Hi Everyone,

I was looking at the function prototype of malloc() function in
stdlib.h and i found that to be,

void *malloc(size_t size);

so what is size_t is it a pre-defined typedef to int?

It can't be. 'int' is a signed integer type; 'size_t' is an unsigned
integer type.

[CBFalconer]

Harald van D?k wrote:

CBFalconer wrote:

>Harald van D?k wrote:

>>sam_...@yahoo .co.in wrote:

I was looking at the function prototype of malloc() function in
stdlib.h and i found that to be,

void *malloc(size_t size);

so what is size_t is it a pre-defined typedef to int?

size_t is a typedef for some unsigned integer type meant to be
capable of storing the size of objects. It is not pre-defined: it
is defined in several of the standard headers, but if you don't
include any of them, you're free to use size_t as an ordinary
identifier in your own code. Which specific type it has depends
on the implementation, and it would be best not to assume
anything more than you need to about it.

No, you are not free to use it for other purposes. You MAY get
away with it on some implementations . You are not free to use
anything defined in any standard headers.

Citation, please?

>From N869:

7.1.3 Reserved identifiers

[#1] Each header declares or defines all identifiers listed
in its associated subclause, and optionally declares or
defines identifiers listed in its associated future library
directions subclause and identifiers which are always
reserved either for any use or for use as file scope
identifiers.

-- All identifiers that begin with an underscore and
either an uppercase letter or another underscore are
always reserved for any use.

-- All identifiers that begin with an underscore are
always reserved for use as identifiers with file scope
in both the ordinary and tag name spaces.

-- Each macro name in any of the following subclauses
(including the future library directions) is reserved
for use as specified if any of its associated headers
is included; unless explicitly stated otherwise (see
7.1.4).

-- All identifiers with external linkage in any of the
following subclauses (including the future library
directions) are always reserved for use as identifiers
with external linkage.143)

_______________ _____

143The list of reserved identifiers with external linkage
includes errno, setjmp, and va_end.

--
"The most amazing achievement of the computer software industry
is its continuing cancellation of the steady and staggering
gains made by the computer hardware industry..." - Petroski

[=?utf-8?B?SGFyYWxkIHZhbiBExLNr?=]

CBFalconer wrote:

Harald van D?k wrote:

CBFalconer wrote:

Harald van D?k wrote:
sam_...@yahoo. co.in wrote:

I was looking at the function prototype of malloc() function in
stdlib.h and i found that to be,

void *malloc(size_t size);

so what is size_t is it a pre-defined typedef to int?

size_t is a typedef for some unsigned integer type meant to be
capable of storing the size of objects. It is not pre-defined: it
is defined in several of the standard headers, but if you don't
include any of them, you're free to use size_t as an ordinary
identifier in your own code. Which specific type it has depends
on the implementation, and it would be best not to assume
anything more than you need to about it.

No, you are not free to use it for other purposes. You MAY get
away with it on some implementations . You are not free to use
anything defined in any standard headers.

Citation, please?

From N869:

7.1.3 Reserved identifiers

7.1.3 applies, but the part that applies is what follows the list of
cases: "No other identifiers are reserved." size_t does not start with
an underscore, its header is not included, and the standard definition
of it has no linkage, so none of the cases that say identifiers are
reserved apply. (You missed one, by the way.)

[=?utf-8?B?SGFyYWxkIHZhbiBExLNr?=]

CBFalconer wrote:

Harald van D?k wrote:

CBFalconer wrote:

Harald van D?k wrote:
sam_...@yahoo. co.in wrote:

I was looking at the function prototype of malloc() function in
stdlib.h and i found that to be,

void *malloc(size_t size);

so what is size_t is it a pre-defined typedef to int?

size_t is a typedef for some unsigned integer type meant to be
capable of storing the size of objects. It is not pre-defined: it
is defined in several of the standard headers, but if you don't
include any of them, you're free to use size_t as an ordinary
identifier in your own code. Which specific type it has depends
on the implementation, and it would be best not to assume
anything more than you need to about it.

No, you are not free to use it for other purposes. You MAY get
away with it on some implementations . You are not free to use
anything defined in any standard headers.

Citation, please?

From N869:

7.1.3 Reserved identifiers

[#1] Each header declares or defines all identifiers listed
in its associated subclause, and optionally declares or
defines identifiers listed in its associated future library
directions subclause and identifiers which are always
reserved either for any use or for use as file scope
identifiers.

-- All identifiers that begin with an underscore and
either an uppercase letter or another underscore are
always reserved for any use.

-- All identifiers that begin with an underscore are
always reserved for use as identifiers with file scope
in both the ordinary and tag name spaces.

-- Each macro name in any of the following subclauses
(including the future library directions) is reserved
for use as specified if any of its associated headers
is included; unless explicitly stated otherwise (see
7.1.4).

-- All identifiers with external linkage in any of the
following subclauses (including the future library
directions) are always reserved for use as identifiers
with external linkage.143)

_______________ _____

143The list of reserved identifiers with external linkage
includes errno, setjmp, and va_end.

You left out

-- Each identifier with file scope listed in any of the following
subclauses (including the future library directions) is reserved
for use as a macro name and as an identifier with file scope in
the same name space if any of its associated headers is included.

So which case applies to an identifier that does not start with _, does
not have its header included, and the standard definition of which has
no linkage? (My apologies if I reply to your message more than once;
I'm having some problems.)