size_t or ssize_t

[Roka100]

Hi,
I am using size_t and ssize_t . But I am confused about them.

<ssize_t>
typedef int __ssize_t;
typedef __ssize_t ssize_t;

<size_t >
typedef unsigned int size_t;

That is:
ssize_t = int
size_t = unsigned int

I see the range of them are :
int ( ssize_t ) : -32767~32767
unsigned int ( size_t ) : 0~65535

My question is : Is that necessary to use ssize_t ? ( size can be minus
? )

Thanks.

[Keith Thompson]

"Ro*****@gmail. com" <Ro*****@gmail. com> writes:

I am using size_t and ssize_t . But I am confused about them.

<ssize_t>
typedef int __ssize_t;
typedef __ssize_t ssize_t;

<size_t >
typedef unsigned int size_t;

That is:
ssize_t = int
size_t = unsigned int

I see the range of them are :
int ( ssize_t ) : -32767~32767
unsigned int ( size_t ) : 0~65535

My question is : Is that necessary to use ssize_t ? ( size can be minus
? )

size_t is defined in <stddef.h>; it's an unsigned type, the result of
the sizeof operator. It won't necessarily be unsigned int (it could
be unsigned long, for example), and it will often have a range greater
than 0..65535.

ssize_t is not defined in standard C. It's a POSIX extension, so you
shouldn't use it if you care about absolute portability.

<OFF_TOPIC>
ssize_t, if it's defined, is the signed equivalent of size_t.
Presumably it should be used only if you need to store negative
values. The Open Group Base Specification says it's "Used for a count
of bytes or an error indication."
</OFF_TOPIC>

--
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.

[Nils O. Selåsdal]

Ro*****@gmail.c om wrote:

Hi,
I am using size_t and ssize_t . But I am confused about them. That is:
ssize_t = int
size_t = unsigned int On your particular machine. Could be something different on
other machines.
I see the range of them are :
int ( ssize_t ) : -32767~32767
unsigned int ( size_t ) : 0~65535

My question is : Is that necessary to use ssize_t ? ( size can be minus
? )

necessary in what context ?

size_t comes from standard C,is an unsigned type used for sizes of objects.

ssize_t comes from posix, is a signed type used for a count of bytes or
an error indication.

[Roka]

Nils O. Selåsdal wrote:

Ro*****@gmail.c om wrote:

Hi,
I am using size_t and ssize_t . But I am confused about them.

That is:
ssize_t = int
size_t = unsigned int

On your particular machine. Could be something different on
other machines.

Yes, I see. I'm using a PC with Fedora Core 4.
Thanks

I see the range of them are :
int ( ssize_t ) : -32767~32767
unsigned int ( size_t ) : 0~65535

My question is : Is that necessary to use ssize_t ? ( size can be minus
? )

necessary in what context ?

size_t comes from standard C,is an unsigned type used for sizes of objects.

ssize_t comes from posix, is a signed type used for a count of bytes or
an error indication.

[Keith Thompson]

"Roka" <Ro*****@gmail. com> writes:

Nils O. Selåsdal wrote:

Ro*****@gmail.c om wrote:

> Hi,
> I am using size_t and ssize_t . But I am confused about them.

> That is:
> ssize_t = int
> size_t = unsigned int

On your particular machine. Could be something different on
other machines.

Yes, I see. I'm using a PC with Fedora Core 4.
Thanks

> I see the range of them are :
> int ( ssize_t ) : -32767~32767
> unsigned int ( size_t ) : 0~65535

Then the maximum value of size_t on your system is almost certainly
2147483647, not 65535.

--
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.

[Roka]

Keith Thompson wrote:

"Roka" <Ro*****@gmail. com> writes:

Nils O. Selåsdal wrote:

Ro*****@gmail.c om wrote:
> Hi,
> I am using size_t and ssize_t . But I am confused about them.

> That is:
> ssize_t = int
> size_t = unsigned int
On your particular machine. Could be something different on
other machines.
Yes, I see. I'm using a PC with Fedora Core 4.
Thanks

> I see the range of them are :
> int ( ssize_t ) : -32767~32767
> unsigned int ( size_t ) : 0~65535

Then the maximum value of size_t on your system is almost certainly
2147483647, not 65535.

Thanks.
But I checked /usr/lib/gcc/i386-redhat-linux/4.0.0/include/stddef.h
size_t is long unsigned int ( 32bit , 0~4294967295 )
and
ssize_t is long ( 32bit, -2147483647~2147 483647)

Is that somewhere wrong? ( long unsigned int is NOT euqal to unsigned
long int ? )

--
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.

[Keith Thompson]

"Roka" <Ro*****@gmail. com> writes:

Keith Thompson wrote:

"Roka" <Ro*****@gmail. com> writes:

> Nils O. Selåsdal wrote:
>> Ro*****@gmail.c om wrote:
>> > Hi,
>> > I am using size_t and ssize_t . But I am confused about them.
>>
>> > That is:
>> > ssize_t = int
>> > size_t = unsigned int
>> On your particular machine. Could be something different on
>> other machines.
>
> Yes, I see. I'm using a PC with Fedora Core 4.
> Thanks
>>
>> > I see the range of them are :
>> > int ( ssize_t ) : -32767~32767
>> > unsigned int ( size_t ) : 0~65535

Then the maximum value of size_t on your system is almost certainly
2147483647, not 65535.

Thanks.
But I checked /usr/lib/gcc/i386-redhat-linux/4.0.0/include/stddef.h
size_t is long unsigned int ( 32bit , 0~4294967295 )
and
ssize_t is long ( 32bit, -2147483647~2147 483647)

Is that somewhere wrong? ( long unsigned int is NOT euqal to unsigned
long int ? )

Oops, my mistake. What I meant to say is that the maximum value of
size_t is 4294967295, not 65535.

(BTW, the minimum value of ssize_t on your system is -2147483648, not
-2147483647.)

--
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.

[Roka]

Keith Thompson wrote:

"Roka" <Ro*****@gmail. com> writes:

Keith Thompson wrote:

"Roka" <Ro*****@gmail. com> writes:
> Nils O. Selåsdal wrote:
>> Ro*****@gmail.c om wrote:
>> > Hi,
>> > I am using size_t and ssize_t . But I am confused about them.
>>
>> > That is:
>> > ssize_t = int
>> > size_t = unsigned int
>> On your particular machine. Could be something different on
>> other machines.
>
> Yes, I see. I'm using a PC with Fedora Core 4.
> Thanks
>>
>> > I see the range of them are :
>> > int ( ssize_t ) : -32767~32767
>> > unsigned int ( size_t ) : 0~65535

Then the maximum value of size_t on your system is almost certainly
2147483647, not 65535.

Thanks.
But I checked /usr/lib/gcc/i386-redhat-linux/4.0.0/include/stddef.h
size_t is long unsigned int ( 32bit , 0~4294967295 )
and
ssize_t is long ( 32bit, -2147483647~2147 483647)

Is that somewhere wrong? ( long unsigned int is NOT euqal to unsigned
long int ? )

Oops, my mistake. What I meant to say is that the maximum value of
size_t is 4294967295, not 65535.

(BTW, the minimum value of ssize_t on your system is -2147483648, not
-2147483647.)

--
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.

Thank you very much.

[Keith Thompson]

"Roka" <Ro*****@gmail. com> writes:

Keith Thompson wrote: [...]

Oops, my mistake. What I meant to say is that the maximum value of
size_t is 4294967295, not 65535.

(BTW, the minimum value of ssize_t on your system is -2147483648, not
-2147483647.)

[...]
Thank you very much.

You're welcome.

When you post a followup, please delete any quoted text that isn't
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In particular, don't quote a signature unless you're actually
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--
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.

[Martin Ambuhl]

Ro*****@gmail.c om wrote:

My question is : Is that necessary to use ssize_t ? ( size can be minus
? )

Since ssize_t is not a standard type in C (but size_t is), it would seem
that ssize_t is not necessary.