twitter: comp.lang.c - 21 new messages in 10 topics

comp.lang.c
http://groups.google.com/group/comp.lang.c?hl=en

comp.lang.c@googlegroups.com

Today's topics:

* Is there a better way to achieve this ? - 4 messages, 3 authors
http://groups.google.com/group/comp.lang.c/t/dd4de60290d2834a?hl=en
* Best way/library to draw individual pixels on screen? (for - 4 messages, 4
authors
http://groups.google.com/group/comp.lang.c/t/bf4e0288d8537985?hl=en
* Reverse and Alphabetize in under 2kb - 4 messages, 4 authors
http://groups.google.com/group/comp.lang.c/t/11babfbf4fe82c07?hl=en
* usage of size_t - 1 messages, 1 author
http://groups.google.com/group/comp.lang.c/t/19e0ad96d01b9898?hl=en
* Stylistic questions on UNIX C coding. - 3 messages, 3 authors
http://groups.google.com/group/comp.lang.c/t/51d2b24a60d73f18?hl=en
* Edward Nilges' lie - 1 messages, 1 author
http://groups.google.com/group/comp.lang.c/t/14c6f4a4afe68f60?hl=en
* EARN MONEY ONLINE WITHOUT INVESTMENT - 1 messages, 1 author
http://groups.google.com/group/comp.lang.c/t/cb7c1e292cdd2a48?hl=en
* books by clc contributors - 1 messages, 1 author
http://groups.google.com/group/comp.lang.c/t/fc106b79706dfb78?hl=en
* UTF-8 and wchar_t - 1 messages, 1 author
http://groups.google.com/group/comp.lang.c/t/6e69f9f50e29243f?hl=en
* günstige immobilien kredite , immobilienfinanzierung eigenkapital , kfw
baufinanzierung , finanzierung von eigentumswohnung , banken hypothek ,
eigenheimzulage 2008 wann , hausfinanzierung online berechnen , - 1 messages,
1 author
http://groups.google.com/group/comp.lang.c/t/0847e3fe134e77ab?hl=en

==============================================================================
TOPIC: Is there a better way to achieve this ?
http://groups.google.com/group/comp.lang.c/t/dd4de60290d2834a?hl=en
==============================================================================

== 1 of 4 ==
Date: Tues, Mar 2 2010 6:42 pm
From: "Mark"

Peter Nilsson wrote:
> On Mar 3, 11:48 am, "Mark" <mark_cruzNOTFORS...@hotmail.com> wrote:
>> Tim Rentsch wrote:
>>> if( a<0 || b<0 || limit<b ) goto end;
>>> if( a > limit - b ) a = limit - b;
>>
>> Why can't we make it as 'if (a+b > limit)' ?
>
> Because a + b can overflow, whereas limit - b can't if
> they're all non-negative.

But you implicitly check 'b' for being negative:

if (b < 0)
{
if (limit <= INT_MAX + b)
if (limit - b < a)

.. then here 'b' is already negative?

--
Mark

== 2 of 4 ==
Date: Tues, Mar 2 2010 7:28 pm
From: Peter Nilsson

"Mark" <mark_cruzNOTFORS...@hotmail.com> wrote:
> Peter Nilsson wrote:
> > "Mark" <mark_cruzNOTFORS...@hotmail.com> wrote:
> > > Tim Rentsch wrote:
> > > > if( a<0 || b<0 || limit<b ) goto end;
> > > > if( a > limit - b ) a = limit - b;
> > >
> > > Why can't we make it as 'if (a+b > limit)' ?
> >
> > Because a + b can overflow, whereas limit - b can't if
> > they're all non-negative.
>
> But you implicitly check 'b' for being negative:
>
> if (b < 0)
> {
> if (limit <= INT_MAX + b)
> if (limit - b < a)
> .. then here 'b' is already negative?

Tim's code checked that a, b, and limit were non-negative.
My code allows a, b, and limit to have any int range value,
although it flags the case where the new value for a would
be outside the range of int.

--
Peter

== 3 of 4 ==
Date: Tues, Mar 2 2010 8:13 pm
From: "Mark"

Peter Nilsson wrote:
> Tim's code checked that a, b, and limit were non-negative.
> My code allows a, b, and limit to have any int range value,
> although it flags the case where the new value for a would
> be outside the range of int.

Hm.. I still can't get it right. Below why there is no check for 'a' being
negative or non-negative?

> The purely general case is...
>
> if (b < 0)
> {
> if (limit <= INT_MAX + b)
Here you check 'limit' and make sure it doesn't overflow? But it doesn't
guarantee limit is non-negative. So 'limi-t-b < a' can be as well overflow..

> if (limit - b < a)
> a = limit - b;
> else
> {
> if (limit < INT_MIN + b)
> goto end; /* a needs to be < INT_MIN : ERROR! */
> if (limit - b < a)
> a = limit - b;
> }

PS. What is the idiom to check sum/subtraction for overflow?

--
Mark

== 4 of 4 ==
Date: Tues, Mar 2 2010 9:42 pm
From: Thad Smith

Francis Moreau wrote:
> On Mar 2, 3:53 pm, Malcolm McLean <malcolm.mcle...@btinternet.com>
> wrote:
>> On Mar 2, 4:42 pm, Francis Moreau <francis.m...@gmail.com> wrote:
>>> I have the following requierement: 3 ints (a, b, limit). The sum of
>>> 'a' and 'b' shouldn't be bigger than limit otherwise 'a' should be
>>> adjusted so that the sum of 'a' and 'b' is equal to 'limit'.
>>> Basically this can be written in C like this:
>>> int a, b, limit;
>>> /* some code that setup the 3 variables */
>>> if (a < 0 || b < 0)
>>> goto end;
>>> if (a + b > b) /* test for overflow (correct with GCC but not
>>> portable) */
>>> goto end;
>>> if (a + b > limit)
>>> a -= a + b - limit;
>>> if (a < 0)
>>> goto end;
>>> /* ... */
>>> So this should work (ok this uses an undefined behaviour but this code
>>> is only intended to be compiled by GCC) but it looks quite
>>> complicated.
>>> Can anybody think to something more 'elegant' ?
>>> Thanks
>> int geta(a, b, limit)
>> {
>> unsigned int t;
>> int answer;
>>
>> if(a >= 0 && b >= 0)
>> {
>> t = (unsigned) a + (unsigned) b;
>> if(t > limit)
>> answer = limit - b;
>> else
>> answer = a;
>> }
>
> This doesn't seem right: for example if a=5 b=600 limit=500
>
> In your case answer is equal to -100, which shouldn't happen since
> answer must be >= 0.

Check the specification above. The only adjustment allowed is to a, and there
was no prohibition against negative numbers. If you want something different,
fix the specification.

--
Thad

==============================================================================
TOPIC: Best way/library to draw individual pixels on screen? (for
http://groups.google.com/group/comp.lang.c/t/bf4e0288d8537985?hl=en
==============================================================================

== 1 of 4 ==
Date: Tues, Mar 2 2010 7:41 pm
From: lacos@ludens.elte.hu (Ersek, Laszlo)

In article <4b8dbe11$0$7637$426a34cc@news.free.fr>, Wolfnoliir <wolfnoliir@gmail.com> writes:
> Seebs a �crit :
>> On 2010-03-03, Wolfnoliir <wolfnoliir@gmail.com> wrote:
>>> Hello,
>>> I would like to know what library and method you would recommend for
>>> displaying individual pixels on the screen in the scope of producing
>>> representations of fractals based on complex iteration
>>
>> Something suitable to my target platform. The answer would be very different
>> for the iPhone than it would for a Linux desktop...
>>
>> Which is to say, this has very little to do with C. Try a group related to
>> the platform.
>>
>> -s
> Thanks but I would prefer something platform independent.

(I wanted to answer this to your original post, but it's just as
relevant now.)

Compute the image in memory and write it out to a ppm file (P6).

http://en.wikipedia.org/wiki/Netpbm_format

The last time I did this was in 2001 or 2002, when I played with
Overhauser splines. It worked great. You can do anything with a ppm
file.

Cheers,
lacos

== 2 of 4 ==
Date: Tues, Mar 2 2010 10:02 pm
From: Wolfnoliir

Ersek, Laszlo a �crit :
> In article <4b8dbe11$0$7637$426a34cc@news.free.fr>, Wolfnoliir <wolfnoliir@gmail.com> writes:
>> Seebs a �crit :
>>> On 2010-03-03, Wolfnoliir <wolfnoliir@gmail.com> wrote:
>>>> Hello,
>>>> I would like to know what library and method you would recommend for
>>>> displaying individual pixels on the screen in the scope of producing
>>>> representations of fractals based on complex iteration
>>> Something suitable to my target platform. The answer would be very different
>>> for the iPhone than it would for a Linux desktop...
>>>
>>> Which is to say, this has very little to do with C. Try a group related to
>>> the platform.
>>>
>>> -s
>> Thanks but I would prefer something platform independent.
>
> (I wanted to answer this to your original post, but it's just as
> relevant now.)
>
> Compute the image in memory and write it out to a ppm file (P6).
>
> http://en.wikipedia.org/wiki/Netpbm_format
>
> The last time I did this was in 2001 or 2002, when I played with
> Overhauser splines. It worked great. You can do anything with a ppm
> file.
>
> Cheers,
> lacos
Thanks for the answers. I may look this idea of ppm file up but the idea
of having to transfer data into a file before displaying it seems very slow.
I also have the impression that some may have misunderstood me: I am not
talking about putting pixels on the screen directly but in a window
actually. I am sorry that my first message was unclear.

== 3 of 4 ==
Date: Tues, Mar 2 2010 11:03 pm
From: Seebs

On 2010-03-03, Wolfnoliir <wolfnoliir@gmail.com> wrote:
> Thanks but I would prefer something platform independent.

Then you are out of luck, because C exists on a broad range of platforms
which don't have "pixels".

Whatever you pick, even if it applies to multiple platforms, you will need
to commit to a set of platforms before you can pick it, and you should
probably pick one of them to start with.

-s
--
Copyright 2010, all wrongs reversed. Peter Seebach / usenet-nospam@seebs.net
http://www.seebs.net/log/ <-- lawsuits, religion, and funny pictures
http://en.wikipedia.org/wiki/Fair_Game_(Scientology) <-- get educated!

== 4 of 4 ==
Date: Tues, Mar 2 2010 11:12 pm
From: Malcolm McLean

On Mar 3, 2:00 am, Wolfnoliir <wolfnol...@gmail.com> wrote:
> Hello,
> I would like to know what library and method you would recommend for
> displaying individual pixels on the screen
>
> I have some knowledge of SDL and OpenGL already.
>
Write into an off-screen buffer using rgb / palette inddex values.
Then use openGL to transfer the buffer to screen in a signle call.
Unfortunatetly the openGL documentation site is so sophisticated that
it keeps crashing my browser, so I couldn't look up the call for you.
The technical term is "blit".

==============================================================================
TOPIC: Reverse and Alphabetize in under 2kb
http://groups.google.com/group/comp.lang.c/t/11babfbf4fe82c07?hl=en
==============================================================================

== 1 of 4 ==
Date: Tues, Mar 2 2010 7:45 pm
From: rudolf

In article
<8a7fb132-246f-4212-8e8b-afa93ff3d15c@s25g2000prd.googlegroups.com>,
Chad <cdalten@gmail.com> wrote:

> On Mar 2, 3:23�pm, Eric Sosman <esos...@ieee-dot-org.invalid> wrote:
> > On 3/2/2010 6:13 PM, Chad wrote:
> >
> > > Here is the job interview question that I drew a blank on.
> >
> > > Make a C program that:
> >
> > > Accepts a string input
> > > Displays the original string
> > > Reverses the order of words in the string ("This is a string" =
> > > "string a is This")
> > > Alphabetizes the letters in each word individually ("hisT is a
> > > ginrst")
> >
> > > It all has to be under 2kb and I can't use strtok().
> >
> > � � �Seems simple enough except for the "under 2kb" part.
> > What's that supposed to mean? �Less than 2KB of source code?
> > All other "2KB" measures I can think of (code size, data
> > size, stack size, heap size, ...) would be entirely platform-
> > dependent and not directly controllable by the way you use
> > the C language. �Even HelloWorld probably takes more than
> > 2KB of executable code on most implementations.
> >
> > --
>
> Yeah, the 2kb part is what confused me. I was just assuming they meant
> the size of the executable file.

You know that you can ask the interviewer questions, right? If you
don't understand what they are asking of you, ask them them to clarify
the question.

== 2 of 4 ==
Date: Tues, Mar 2 2010 7:52 pm
From: pete

Eric Sosman wrote:
> On 3/2/2010 6:13 PM, Chad wrote:
>
>> Here is the job interview question that I drew a blank on.
>>
>> Make a C program that:

>> It all has to be under 2kb and I can't use strtok().
>
>
> Seems simple enough except for the "under 2kb" part.
> What's that supposed to mean?

The assignment as stated, is to make a C program.

A C program is composed of text files.

--
pete

== 3 of 4 ==
Date: Tues, Mar 2 2010 10:40 pm
From: Richard Heathfield

Chad wrote:
> Here is the job interview question that I drew a blank on.
>
> Make a C program that:
>
> Accepts a string input
> Displays the original string
> Reverses the order of words in the string ("This is a string" =
> "string a is This")
> Alphabetizes the letters in each word individually ("hisT is a
> ginrst")
>
> It all has to be under 2kb and I can't use strtok().

The trick to this question is to realise that the third stage (reversing
the word order) is greatly simplified by the fourth stage (alphabetising
the letters in each word). In stage 3, it is sufficient to reverse the
entire string; you don't need to detect word boundaries at that point.

Stage 4 then becomes a simple parse-and-qsort loop.

--
Richard Heathfield <http://www.cpax.org.uk>
Email: -http://www. +rjh@
"Usenet is a strange place" - dmr 29 July 1999
Sig line vacant - apply within

== 4 of 4 ==
Date: Tues, Mar 2 2010 11:15 pm
From: Michael Foukarakis

On Mar 3, 1:13 am, Chad <cdal...@gmail.com> wrote:
> Here is the job interview question that I drew a blank on.
>
> Make a C program that:
>
> Accepts a string input
> Displays the original string
> Reverses the order of words in the string ("This is a string" =
> "string a is This")

Is the output from this stage needed to be made visible?

> Alphabetizes the letters in each word individually ("hisT is a
> ginrst")

I assume, from your parenthesized example, this is independent
(conceptually) from stage 3?

==============================================================================
TOPIC: usage of size_t
http://groups.google.com/group/comp.lang.c/t/19e0ad96d01b9898?hl=en
==============================================================================

== 1 of 1 ==
Date: Tues, Mar 2 2010 8:13 pm
From: "Chris M. Thomasson"

"Richard Heathfield" <rjh@see.sig.invalid> wrote in message
news:B6idnXD2mMLcwhXWnZ2dnUVZ8ldi4p2d@bt.com...
> Chris M. Thomasson wrote:
> <snip>
>
>> Does something like that sound workable to you?
>
> Chris: I'd like to give you a considered reply, but I lack the time right
> now to do your question justice (e.g. by reading your article with
> sufficient care). If you could possibly remind me in a few days, I'll do
> my best to pay your article the attention it looks like it deserves.

I was thinking that one might want to special case a pointer wrt a
value-based container.

==============================================================================
TOPIC: Stylistic questions on UNIX C coding.
http://groups.google.com/group/comp.lang.c/t/51d2b24a60d73f18?hl=en
==============================================================================

== 1 of 3 ==
Date: Tues, Mar 2 2010 8:25 pm
From: Nizumzen

On 2010-02-26 23:54:08 +0000, Richard said:
>
> because it does the same thing in one line less with ZERO reduction in
> readability.

I find there is zero reduction in readability in that style, ergo
everyone must find that there is zero reduction in readability.

Anyway with that coding style you end up with this abomination:

if(x == 0) {
// blah
} else if(x == 1) {
// blah
} else {
// blah
}

Go, go Java coding standards!

== 2 of 3 ==
Date: Tues, Mar 2 2010 8:42 pm
From: Keith Thompson

Nizumzen <blah@mcnuggets.com> writes:
> On 2010-02-26 23:54:08 +0000, Richard said:
>> because it does the same thing in one line less with ZERO reduction in
>> readability.
>
> I find there is zero reduction in readability in that style, ergo
> everyone must find that there is zero reduction in readability.
>
> Anyway with that coding style you end up with this abomination:
>
> if(x == 0) {
> // blah
> } else if(x == 1) {
> // blah
> } else {
> // blah
> }

Here's how I would write the above:

if (x == 0) {
// blah
}
else if (x == 1) {
// blah
}
else {
// blah
}

In my preferred style, a closing brace appears on a line by itself, or
possibly followed by a comment. Some people like to put "else" on the
same line as the preceding "}"; I don't.

I don't suggest that everyone needs to code this way. Nor do I
suggest that any consistent style is an "abomination".

--
Keith Thompson (The_Other_Keith) kst-u@mib.org <http://www.ghoti.net/~kst>
Nokia
"We must do something. This is something. Therefore, we must do this."
-- Antony Jay and Jonathan Lynn, "Yes Minister"

== 3 of 3 ==
Date: Tues, Mar 2 2010 10:42 pm
From: Richard Heathfield

Ben Bacarisse wrote:

<snip>

> They were arguing about what editor *other* people should use and that
> is widely thought to be an argument that never ends. :-)

s/widely/widely but wrongly/

Everybody should use vim, obviously. End of argument.

--
Richard Heathfield <http://www.cpax.org.uk>
Email: -http://www. +rjh@
"Usenet is a strange place" - dmr 29 July 1999
Where do I put the smiley on this occasion?

==============================================================================
TOPIC: Edward Nilges' lie
http://groups.google.com/group/comp.lang.c/t/14c6f4a4afe68f60?hl=en
==============================================================================

== 1 of 1 ==
Date: Tues, Mar 2 2010 8:27 pm
From: Kelsey Bjarnason

[snips]

On Mon, 01 Mar 2010 17:53:12 +0800, Colonel Harlan Sanders wrote:

> Nilges' uncharacteristic modesty betrays him. No one here even comes
> close to being so consistently and grossly offensive as Nilges.

Damn, I'll have to try harder. Obviously, the "spaces vs tabs" thing
just didn't cut it.

How about "Scott Nudds for president!" ?

==============================================================================
TOPIC: EARN MONEY ONLINE WITHOUT INVESTMENT
http://groups.google.com/group/comp.lang.c/t/cb7c1e292cdd2a48?hl=en
==============================================================================

== 1 of 1 ==
Date: Tues, Mar 2 2010 10:17 pm
From: MY NAME IS MY NAME

EARN MONEY ONLINE WITHOUT INVESTMENT

Simple Online Jobs that makes your life settled just by staying at
home and working on your free time.

Visit http://earnmoneyonline-without-investment.blogspot.com/ and Join
to our specified Websites to start earning from now.

Overview :

Information :

Act upon at base, net capers, irregular jobs, dwelling based chores,
web chores, Data debut businesses

Beloved Internet ally, wanted.
Gracious to contact you through with this website. These site is
entirely designed because Amerind* who deprivations to clear net worth
through domicile grounded web farms out without any investiture, who
can spend but fewer hours in a day. Combine U.S.A., you leave make
universal gas constant*. 50000 and further from this month.

What lives the actualised work?
The existent capers costs meeting online information debut forms
inwards the web. We will equal catering you bare internet readjustment
classes. You birth to make full those Online adjustment builds
according to the instructions.

Constitutes it easily to fill those enrolment casts?
Uh-huh. These are rattling dewy-eyed data entranceway chassises and it
constitutes similar to producing an e-mail account inch chawbacon,
hotmail or rediff. It takes to a lesser degree 2 instants to fill
those chassises. This is standardised to Data entry farms out.

How often I can earn for pick each forms?
You can earn between Rs.50 to Rs.100 for each data entree class you
fill. We experience numerous categories of configurations to meet.
Grounded on the category, the rate will vary. Upon an mediocre, you
could earn Rs.75 for each build you fill.

==============================================================================
TOPIC: books by clc contributors
http://groups.google.com/group/comp.lang.c/t/fc106b79706dfb78?hl=en
==============================================================================

== 1 of 1 ==
Date: Tues, Mar 2 2010 10:46 pm
From: Phred Phungus

Ben Pfaff wrote:
> Phred Phungus <Phred@example.invalid> writes:
>
>> Ben Pfaff wrote:
>>> In the future, I am more likely to release my writings for free
>>> on the Internet than to write them for a publisher, at least if
>>> the publisher gets all the rights. I hear a lot more about GNU
>>> libavl (which is sort of an online book of mine) than I ever do
>>> about C Unleashed.
>> I don't mean to compound your frustration here, but is this library
>> from the avl that came on the source disc?
>
> No, it is at http://adtinfo.org.

Can you say a few words about glib? In particular, is GTK+ something
relevant to ubuntu?
>
>> What rights do you mean here? Isn't it somwewhat contrary to the gnu
>> license to restrict distribution?
>
> I mean, I signed over the copyright and other rights to the text
> of that chapter to the publisher.

So you can't use your own tree chapter. Get the same crew together for
the same material, but derange the association between author and
chapter. Publish it exerting your own rights.
--
fred

==============================================================================
TOPIC: UTF-8 and wchar_t
http://groups.google.com/group/comp.lang.c/t/6e69f9f50e29243f?hl=en
==============================================================================

== 1 of 1 ==
Date: Tues, Mar 2 2010 11:38 pm
From: Nick <3-nospam@temporary-address.org.uk>

Nobody <nobody@nowhere.com> writes:

> On Tue, 02 Mar 2010 19:16:20 +0100, Ersek, Laszlo wrote:
>
>> For the UTF-8 input coming from elsewhere: if you can stick with glibc,
>> just call
>>
>> #include <iconv.h>
>>
>> convdesc = iconv_open("WCHAR_T", "UTF-8");
>
> Or you can write your own UTF-8 encoder/decoder. Personally, I wouldn't
> make iconv a requirement just for UTF-8. If you're going to be using iconv
> anyhow, then you may as well use it for this as well.

I found sqlite3_unicode a great help when doing that - lots of stuff to
start you off and no copyright issues:

You can find it at:
<URL:http://ioannis.mpsounds.net/blog/2009/01/11/sqlite3_unicode-updated-for-sqlite3-v367/>

(it's not that ioannis btw).
--
Online waterways route planner | http://canalplan.eu
Plan trips, see photos, check facilities | http://canalplan.org.uk

==============================================================================
TOPIC: günstige immobilien kredite , immobilienfinanzierung eigenkapital , kfw
baufinanzierung , finanzierung von eigentumswohnung , banken hypothek ,
eigenheimzulage 2008 wann , hausfinanzierung online berechnen ,
http://groups.google.com/group/comp.lang.c/t/0847e3fe134e77ab?hl=en
==============================================================================

== 1 of 1 ==
Date: Tues, Mar 2 2010 11:47 pm
From: gert analeo

günstige immobilien kredite , immobilienfinanzierung eigenkapital ,
kfw baufinanzierung , finanzierung von eigentumswohnung , banken
hypothek , eigenheimzulage 2008 wann , hausfinanzierung online
berechnen ,

für immobilienkredit hypotheken finanzierung
günstigste hypothek eigenheimzulage kosten
hypothek zinsen darlehen eigentumswohnung
hypothek tilgung banken hypothek
baufinanzierung 2007 baufinanzierung info
günstig haus finanzieren hausfinanzierung was
zinsentwicklung immobilienfinanzierung günstige haus finanzierung
zur hausfinanzierung zur immobilienfinanzierung
finanzierung immobilie ohne eigenheimzulage rückwirkend
bauspardarlehen im vergleich bauspardarlehen zu
immobilienfinanzierung was hausfinanzierung von
durch bauspardarlehen zinstrend baufinanzierung
www hausfinanzierung de wie haus finanzieren

==============================================================================

You received this message because you are subscribed to the Google Groups "comp.lang.c"
group.

To post to this group, visit http://groups.google.com/group/comp.lang.c?hl=en

To unsubscribe from this group, send email to comp.lang.c+unsubscribe@googlegroups.com

To change the way you get mail from this group, visit:
http://groups.google.com/group/comp.lang.c/subscribe?hl=en

To report abuse, send email explaining the problem to abuse@googlegroups.com

==============================================================================
Google Groups: http://groups.google.com/?hl=en

twitter

Wednesday, March 3, 2010

comp.lang.c - 21 new messages in 10 topics - digest

0 Comments:

Post a Comment

About Me

Previous Posts