FAQ issue: Guaranteed value ranges of fundamental types?

[Alf P. Steinbach]

The C++ FAQ item 29.5 (this seems to be strongly related to C), at
<url: http://www.parashift.c om/c++-faq-lite/newbie.html#faq-29.5>
mentions that

<quote>
C++ guarantees a char is exactly one byte which is at least 8 bits, short
is at least 16 bits, int is at least 16 bits, and long is at least 32
bits.
</quote>
Questions:

(1) This guarantee seems to come from the C standard. Which I don't
have. Does the C++ standard really guarantee this?

(2) Is this guarantee originally formulated in terms of number of bits,
or in terms of e.g. decimal value ranges?

(3) Concerning (2), if formulated in terms of number of bits, are the number
of bits mentioned simply sizeof(T)*CHAR_ BIT, which doesn't say much about
value ranges, or are they stated to be the value representation bits?
(Intentionally cross-posted [comp.lang.c++] and [comp.lang.c]).

--
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?

[Andreas Huber]

Victor Bazarov wrote:

"Andreas Huber" <ah************ ********@yahoo. com> wrote...

Alf P. Steinbach wrote:
[snip]

short is at least 16 bits, int is at least 16 bits, and long
is at least 32 bits.
</quote>
That is contrary to what my copy of the standard says (see 3.9.1/1).
It basically says that char <= short <= int <= long (i.e. there is no

I wonder what _exactly_ does your copy say in 3.9.1/1 that makes you
derive that 'char <= short <= int'.

I was wrong, it's actually 3.9.1/2...
But that doesn't matter. You are
actually correct, the C standard defined those relationships between
type sizes. It is true that char <= short <= int. It does not,
however, mean that there is no guarantee that 'int' is larger than
'char'. The same C90 Standard when describing <limits.h> (and see
18.2.2/2 to know that C++ mandates the same values for all xx_MAX and
xx_MIN values), does require *at least* ranges -32767..32767 for
'int' and -2^31..2^31 for 'long'.

guarantee that a long is any bigger than a char, although there
probably is no platform where sizeof(long) == sizeof(char)). For
more information see 5.3.3 and 1.7..

For more information see 18.2.2

<blush> Ok, you got me on the left foot there. Although the C++ standard
does not itself guarantee anything like that, it *refers* to C standard
of which I don't even have a copy available... oh well.

Thanks for clarifying.

Regards,

--
Andreas Huber

When replying by private email, please remove the words spam and trap
from the address shown in the header.

[CBFalconer]

"Alf P. Steinbach" wrote:

CBFalconer:

"Alf P. Steinbach" wrote:

.... snip ...
(1) This guarantee seems to come from the C standard. Which I
don't have. Does the C++ standard really guarantee this?

I dunno. This is c.l.c. Google for N869 to get the last draft of
the C standard. f'ups set, which you should have done in the
original posting.

It was intentionally cross-posted; F.U.T. overridden. :-)

You got your inputs from c.l.c, now it should go away. That's why
you should have set fups in the first place, and not have
overridden mine. Notice I didn't object to the initial cross-post.

--
"If you want to post a followup via groups.google.c om, don't use
the broken "Reply" link at the bottom of the article. Click on
"show options" at the top of the article, then click on the
"Reply" at the bottom of the article headers." - Keith Thompson

[CBFalconer]

Ioannis Vranos wrote:

Alf P. Steinbach wrote:

.... snip ...

(1) This guarantee seems to come from the C standard. Which I
don't have. Does the C++ standard really guarantee this?

Yes. Also, except where otherwise is stated, C90 is a subset of
C++98 standard.

See what happens when you don't set followups in the initial
query. Misinformation like this works its way into c.l.c and is
likely to produce an interminable stupid cross group argument.
It's bad enough when the misinformation is native to the group.

--
"If you want to post a followup via groups.google.c om, don't use
the broken "Reply" link at the bottom of the article. Click on
"show options" at the top of the article, then click on the
"Reply" at the bottom of the article headers." - Keith Thompson

[Jack Klein]

On Sat, 05 Feb 2005 13:11:04 GMT, al***@start.no (Alf P. Steinbach)
wrote in comp.lang.c:

The C++ FAQ item 29.5 (this seems to be strongly related to C), at
<url: http://www.parashift.c om/c++-faq-lite/newbie.html#faq-29.5>
mentions that

<quote>
C++ guarantees a char is exactly one byte which is at least 8 bits, short
is at least 16 bits, int is at least 16 bits, and long is at least 32
bits.
</quote>
Questions:

(1) This guarantee seems to come from the C standard. Which I don't
have. Does the C++ standard really guarantee this?

[snip]

The fact that the C++ standard decided to cite the C standard as a
normative reference is irrelevant here in comp.lang.c. The POSIX
standard is also based on the C standard, but that doesn't make POSIX
topical in comp.lang.c either.

What the C++ language guarantees is 100% off-topic in c.l.c, period.
The fact that the C++ standard does or does not refer to any or all
parts of the C standard has no meaning at all in terms of C.

--
Jack Klein
Home: http://JK-Technology.Com
FAQs for
comp.lang.c http://www.eskimo.com/~scs/C-faq/top.html
comp.lang.c++ http://www.parashift.com/c++-faq-lite/
alt.comp.lang.l earn.c-c++
http://www.contrib.andrew.cmu.edu/~a...FAQ-acllc.html

[Alf P. Steinbach]

* Jack Klein:

On Sat, 05 Feb 2005 13:11:04 GMT, al***@start.no (Alf P. Steinbach)
wrote in comp.lang.c:

The C++ FAQ item 29.5 (this seems to be strongly related to C), at
<url: http://www.parashift.c om/c++-faq-lite/newbie.html#faq-29.5>
mentions that

<quote>
C++ guarantees a char is exactly one byte which is at least 8 bits, short
is at least 16 bits, int is at least 16 bits, and long is at least 32
bits.
</quote>
Questions:

(1) This guarantee seems to come from the C standard. Which I don't
have. Does the C++ standard really guarantee this?

[snip]

The fact that the C++ standard decided to cite the C standard as a
normative reference is irrelevant here in comp.lang.c. The POSIX
standard is also based on the C standard, but that doesn't make POSIX
topical in comp.lang.c either.

What the C++ language guarantees is 100% off-topic in c.l.c, period.
The fact that the C++ standard does or does not refer to any or all
parts of the C standard has no meaning at all in terms of C.

You mean, you don't have the slightest clue about the C aspects (although
you could easily check up on that, since you do have that standard), and
therefore choose to answer the 1/3 C++ part -- with some sour grapes.

Have a nice weekend.

--
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?

[Jack Klein]

On Sun, 06 Feb 2005 02:16:08 GMT, al***@start.no (Alf P. Steinbach)
wrote in comp.lang.c:

* Jack Klein:

On Sat, 05 Feb 2005 13:11:04 GMT, al***@start.no (Alf P. Steinbach)
wrote in comp.lang.c:

The C++ FAQ item 29.5 (this seems to be strongly related to C), at
<url: http://www.parashift.c om/c++-faq-lite/newbie.html#faq-29.5>
mentions that

<quote>
C++ guarantees a char is exactly one byte which is at least 8 bits, short
is at least 16 bits, int is at least 16 bits, and long is at least 32
bits.
</quote>
Questions:

(1) This guarantee seems to come from the C standard. Which I don't
have. Does the C++ standard really guarantee this?

[snip]

The fact that the C++ standard decided to cite the C standard as a
normative reference is irrelevant here in comp.lang.c. The POSIX
standard is also based on the C standard, but that doesn't make POSIX
topical in comp.lang.c either.

What the C++ language guarantees is 100% off-topic in c.l.c, period.
The fact that the C++ standard does or does not refer to any or all
parts of the C standard has no meaning at all in terms of C.

You mean, you don't have the slightest clue about the C aspects (although
you could easily check up on that, since you do have that standard), and
therefore choose to answer the 1/3 C++ part -- with some sour grapes.

Yes, I do, and had you posted this to comp.lang.c++ ONLY, I would have
been happy to answer based on what the C++ standard inherits from the
C standard.

But whether the C++ standard decided to incorporate the C standard in
its entirety, which it does not, or decided to only incorporate the
third comma on page 47, which it also does not, it not a C language
issue or topical for comp.lang.c at all.

There is no mention of the C++ language at all in the (now superceded
version) of the C standard that C++ chose to incorporate.

--
Jack Klein
Home: http://JK-Technology.Com
FAQs for
comp.lang.c http://www.eskimo.com/~scs/C-faq/top.html
..lang.c++ http://www.parashift.com/c++-faq-lite/
alt.comp.lang.l earn.c-c++
http://www.contrib.andrew.cmu.edu/~a...FAQ-acllc.html

[Mark McIntyre]

On Sat, 5 Feb 2005 20:30:18 +0000 (UTC), in comp.lang.c , infobahn
<in******@btint ernet.com> wrote:

Victor Bazarov wrote:

I wonder what _exactly_ does your copy say in 3.9.1/1 that makes you
derive that 'char <= short <= int'. But that doesn't matter. You are
actually correct, the C standard defined those relationships between
type sizes.

C&V please.

5.2.4.2.1 Sizes of Integral types.


--
Mark McIntyre
CLC FAQ <http://www.eskimo.com/~scs/C-faq/top.html>
CLC readme: <http://www.ungerhu.com/jxh/clc.welcome.txt >

[Mark McIntyre]

On Sun, 06 Feb 2005 02:16:08 GMT, in comp.lang.c , al***@start.no (Alf P.
Steinbach) wrote:

* Jack Klein:

What the C++ language guarantees is 100% off-topic in c.l.c, period.
The fact that the C++ standard does or does not refer to any or all
parts of the C standard has no meaning at all in terms of C.

You mean, you don't have the slightest clue about the C aspects

Before posting such remarks, you might want to check up on Jack's
credentials, posting history etc. You just made a fool of yourself.
--
Mark McIntyre
CLC FAQ <http://www.eskimo.com/~scs/C-faq/top.html>
CLC readme: <http://www.ungerhu.com/jxh/clc.welcome.txt >

[Keith Thompson]

Mark McIntyre <ma**********@s pamcop.net> writes:

On Sat, 5 Feb 2005 20:30:18 +0000 (UTC), in comp.lang.c , infobahn
<in******@btint ernet.com> wrote:

Victor Bazarov wrote:

I wonder what _exactly_ does your copy say in 3.9.1/1 that makes you
derive that 'char <= short <= int'. But that doesn't matter. You are
actually correct, the C standard defined those relationships between
type sizes.

C&V please.

5.2.4.2.1 Sizes of Integral types.

Which actually discusses the ranges of integer types, which, in the
presence of padding bits, may not be directly related to their sizes.
A sufficiently perverse implementation could have
sizeof(long) < sizeof(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.

[Alf P. Steinbach]

* Mark McIntyre:

On Sun, 06 Feb 2005 02:16:08 GMT, in comp.lang.c , al***@start.no (Alf P.
Steinbach) wrote:

* Jack Klein:

What the C++ language guarantees is 100% off-topic in c.l.c, period.
The fact that the C++ standard does or does not refer to any or all
parts of the C standard has no meaning at all in terms of C.
You mean, you don't have the slightest clue about the C aspects

Before posting such remarks, you might want to check up on Jack's
credentials, posting history etc.

I know Jack's posting history for several years.

You just made a fool of yourself.

Before posting such remarks, you might want to check up on my
credentials, posting history etc.

--
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?