Convert VB code to C code.

[Sebastian Kaliszewski]

Re: Convert VB code to C code.

Richard Bos wrote:
[color=blue]
> John Smith <JSmith@mail.ne t> wrote:
>
>[color=green]
>>Essentially , strings in C are arrays of characters, terminated with a
>>NULL character.[/color]
>
>
> _Null_ character, please. Case is important. NULL is a macro expanding
> to a null pointer constant, not a character. (void *)0 is hardly a good
> string terminator, let alone '(void *)0'.[/color]

Well, according to standard NULL should expand to 0. (void*)0 is not
conformant IMHO (some pre C89 compilers did so)

rgds
Sebastian

[Richard Bos]

Re: Convert VB code to C code.

Sebastian Kaliszewski <sk@bez.spamu.z .pl> wrote:
[color=blue]
> Richard Bos wrote:
>[color=green]
> > John Smith <JSmith@mail.ne t> wrote:
> >[color=darkred]
> >>Essentially , strings in C are arrays of characters, terminated with a
> >>NULL character.[/color]
> >
> > _Null_ character, please. Case is important. NULL is a macro expanding
> > to a null pointer constant, not a character. (void *)0 is hardly a good
> > string terminator, let alone '(void *)0'.[/color]
>
> Well, according to standard NULL should expand to 0. (void*)0 is not
> conformant IMHO[/color]

Ahem. Neither your humble nor my arrogant opinion are worth what the cat
dragged in; it is the Standard which defines C, not our opinion. And the
Standard says:

7.17#3:
# 3 The macros are
# NULL
# which expands to an implementation-defined null pointer constant;

6.3.2.3#3:
# 3 An integer constant expression with the value 0, or such an
# expression cast to type void *, is called a null pointer constant.

0 is an integer constant expression with the valud 0; (void *)0 is such
an expression cast to type void *; it is, therefore, a null pointer
constant; and because of that, it is a valid expansion of NULL.
[color=blue]
> (some pre C89 compilers did so)[/color]

There was no such thing as void, pre-C89. IIRC the Standard Committee
nicked it from C++.

Richard

[pete]

Re: Convert VB code to C code.

Sebastian Kaliszewski wrote:
[color=blue]
> Well, according to standard NULL should expand to 0. (void*)0 is not
> conformant IMHO (some pre C89 compilers did so)[/color]

What standard would that be?

N869
7.17 Common definitions <stddef.h>
[#3] The macros are
NULL
which expands to an implementation-defined null pointer
constant;
6.3.2.3 Pointers
[#3] An integer constant expression with the value 0, or
such an expression cast to type void *, is called a null
pointer constant.



C89 last public draft
4.1.5 Common definitions <stddef.h>
The macros are
NULL
which expands to an implementation-defined null pointer constant;
3.2.2.3 Pointers
An integral constant expression with the value 0, or such an
expression cast to type void * , is called a null pointer constant.

--
pete

[dandelion]

Re: Convert VB code to C code.


"Richard Bos" <rlb@hoekstra-uitgeverij.nl> wrote in message
news:4190df39.1 08259609@news.i ndividual.net.. .
[color=blue]
> There was no such thing as void, pre-C89. IIRC the Standard Committee
> nicked it from C++.[/color]

You don't.

It was defined in the first ANSI-C (as opposed to old-style K&R) I used.
That was in '89. C++ was nowhere in sight. Yet.

See

http://www.ericgiguere.com/articles/ansi-c-summary.html

So much for Mr Professional... Don't you wish you had studied at the RUG?

[pete]

Re: Convert VB code to C code.

dandelion wrote:
[color=blue]
> That was in '89. C++ was nowhere in sight. Yet.[/color]

I'm seeing C++ from 1983.

http://www.google.com/search?hl=en&ie=ISO-8859-1&q=%22c%2B%2B%22+history

--
pete

[Chris Torek]

Re: Convert VB code to C code.

>"Richard Bos" <rlb@hoekstra-uitgeverij.nl> wrote in message[color=blue]
>news:4190df39. 108259609@news. individual.net. ..[color=green]
>> There was no such thing as void, pre-C89. IIRC the Standard Committee
>> nicked it from C++.[/color][/color]

No, the "void" type itself (but not "void *") appeared some time
around 1979 or so, about the same time as PWB-Unix and Steve
Johnson's Portable C Compiler. ("void" and "enum" appeared about
the same time. PCC also introduced separated struct/enum namespaces
-- you could now write:

struct A { int a; int b; };
struct B { int b; int a; };

which in Dennis Ritchie's older compilers was invalid; all "struct"
members were in a single namespace, so each had to have a unique
name. This is at least part of the reason that Unix-y "struct"s
use per-struct member prefixes, e.g., "tm_year" inside a "struct
tm", or "st_dev" inside a "struct stat" -- not just "year" and
"dev". PCC had a backwards-compatiblility hack: if X was any
lvalue, or P was a pointer with structure type S, and you wrote
X.field or P->field, and "field" was not a member of the structure
S, PCC would search all the other "struct" and "union" types for
the first one with a member named "field", use that field's type
and offset, and emit a warning. Among other things, this meant
you could write:

struct { char lo, hi; };
short s;
...
s = some_expression ();
printf("as word: %o; as bytes: %o, %o\n", s, s.lo, s.hi);

and the old "adb" program used this very construct. Yes, it
sign-extended the bytes, which I found quite annoying. Of course,
Dennis' original compilers did not have "unsigned char" either --
PCC added unsigned variants of all the integral types. Indeed,
early C had no "unsigned" keyword at all; if you wanted unsigned
integers, you declared pointers!)

The "void *" type was an ANSI-committee invention, though.

In article <news:4190e3e5$ 0$9264$e4fe514c @dreader10.news .xs4all.nl>
dandelion <dandelion@mead ow.net> wrote:[color=blue]
>It was defined in the first ANSI-C (as opposed to old-style K&R) I used.
>That was in '89. C++ was nowhere in sight. Yet.[/color]

This is not quite right either. The original ANSI C standard came
out in December 1989, yes, but Stroustrup's C++ book was out well
before that -- I believe I read it in 1986, and apparently it was
published in 1985. Of course, that particular C++ was a very
different language from today's C++.
--
In-Real-Life: Chris Torek, Wind River Systems
Salt Lake City, UT, USA (40°39.22'N, 111°50.29'W) +1 801 277 2603
email: forget about it http://web.torek.net/torek/index.html
Reading email is like searching for food in the garbage, thanks to spammers.

[Dan Pop]

Re: Convert VB code to C code.

In <cmqsmd015ut@ne ws4.newsguy.com > Chris Torek <nospam@torek.n et> writes:
[color=blue][color=green]
>>"Richard Bos" <rlb@hoekstra-uitgeverij.nl> wrote in message
>>news:4190df39 .108259609@news .individual.net ...[color=darkred]
>>> There was no such thing as void, pre-C89. IIRC the Standard Committee
>>> nicked it from C++.[/color][/color]
>
>No, the "void" type itself (but not "void *") appeared some time
>around 1979 or so, about the same time as PWB-Unix and Steve
>Johnson's Portable C Compiler. ("void" and "enum" appeared about
>the same time.[/color]

"enum" predates "void". It was introduced with the V7 compiler, together
with better support for structures (structures as function parameters and
as function return types, as well as simple assignment operands), slightly
after K&R1 went to print.

Dan
--
Dan Pop
DESY Zeuthen, RZ group
Email: Dan.Pop@ifh.de
Currently looking for a job in the European Union

[ozbear]

Re: Convert VB code to C code.

On Tue, 09 Nov 2004 13:54:54 GMT, rlb@hoekstra-uitgeverij.nl (Richard
Bos) wrote:
[color=blue]
>John Smith <JSmith@mail.ne t> wrote:
>[color=green]
>> Essentially, strings in C are arrays of characters, terminated with a
>> NULL character.[/color]
>
>_Null_ character, please. Case is important. NULL is a macro expanding
>to a null pointer constant, not a character. (void *)0 is hardly a good
>string terminator, let alone '(void *)0'.
>
>Richard[/color]

That is one valid expansion. It is also allowed to expand to an
unadorned 0 which will give the correct result, but for the
wrong reason (i.e., luck) when depended upon.

Oz
--
A: Because it fouls the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing on usenet and in e-mail?

[Frank Adam]

Re: Convert VB code to C code.

On Tue, 09 Nov 2004 14:27:57 GMT, pete <pfiland@mindsp ring.com> wrote:
[color=blue]
>Richard Bos wrote:[color=green]
>>
>> John Smith <JSmith@mail.ne t> wrote:
>>[color=darkred]
>> > Essentially, strings in C are arrays of characters,
>> > terminated with a
>> > NULL character.[/color]
>>
>> _Null_ character, please. Case is important.[/color]
>
>or "null character",
>since it's not at the begining ofasentence.
>[color=green]
>> NULL is a macro expanding
>> to a null pointer constant, not a character.[/color]
>
>... and a null pointer is a pointer
>that compares equal to a null pointer constant.
>[/color]
How about a Null (pointer) and a Nul (character) ? :)

Jaysus, i remember you guys bickering on this many moons ago when i
frequented the C echos.... and you are still fighting over it ?

Just settle on 'zero' already. ;-)

--

Regards, Frank