On Jan 11, 2004, at 17:07, Philippe Verdy wrote:
----- Original Message ----- From: "Hallvard B Furuseth" <[EMAIL PROTECTED]> To: "Philippe Verdy" <[EMAIL PROTECTED]> Cc: "Clark Cox" <[EMAIL PROTECTED]>; "Unicode Mailing List" <[EMAIL PROTECTED]> Sent: Sunday, January 11, 2004 8:18 PM Subject: Re: [OT] ASCII support in C/C++ (was: doubt)
Philippe Verdy writes:here...From: "Clark Cox" <[EMAIL PROTECTED]>Actually, both the C and C++ standards require that the char type be
at least 8-bits. that is, the signed char type must be able to
represent the values in the range [-127, 127], and the unsigned char
type must be able to represent the values in the range [0, 255]. Any C
or C++ compiler that cannot meet those requirements is non-conformant.
Yes of course (however this depends on which standard you discussguidelines
No, it doesn't.
The language itself does not require it, just the implementationfor applications on generic OS.
The C and C++ languages are defined by the C and C++ standards. As Clark says, the standards do require this. See for example ISO C section 5.2.4.2.1 (Sizes of integer types <limits.h>).
If you look at some C compilers created for microcontrolers or hardware
devices, you'll see that it supports the full core language,
If it does, it has 8-bit 'char' or wider. Otherwise it is not a C compiler, however much it might claim to be. It is a compiler for a language _ressembling_ C.
All this relates to the language that was standardized very lately by ISO
and initially by ANSI (in collaboration with the initial designers Kernighan
and Richie who designed the language to write Unix).
C was standardized quite a while ago (1989). There may very well still be K&R implementations all over the place, but those are "K&R C", not "C". The language known as "C" is defined by the ISO standard. Claiming that "C" is still defined by K&R is like claiming that "Unicode" is still defined by Unicode 1.0.
There are still a lot
of code needing support of the K&R C language, which is a de-facto (rather
than de-jure) standard, as it was specified in the first edition of "the C
language" by Brian Kernighan & Dennis Richie (Prentice-Hall, 1978) and
translated into languages (1983 for the French edition) .
There are still a lot of systems which ONLY support a K&R C compliant
compiler (without "void", "signed char", "long long", and function
prototypes) but not the ANSI C american standard, or the late ISO C
standard. And most of these systems do not have all what is required to
support POSIX. And lots of other C++ compilers that were written and used on
systems long before the ISO C standard was published, and still not
implementing the full ANSI C standard.
You keep making a distinction between the ANSI C standard and the ISO C standard; the two are identical except for some formatting and the table of contents. ANSI C 1989 is the same as ISO C 1990, and ANSI and ISO C 1999 are the same.
Not all platforms are supporting fully IEEE-compliant floatting point operations as well (because there's no FPU and fully implementing it by software would impact too much performance). So the POSIX and ISO C requirements cannot be applied to these systems. Note that even on PC systems, the FPU is not always fully IEEE-compliant,
C has no requirement that systems be IEEE compliant with respect to floating point numbers.
-- Clark S. Cox III [EMAIL PROTECTED] http://homepage.mac.com/clarkcox3/ http://homepage.mac.com/clarkcox3/blog/B1196589870/index.html
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