[19855] in Perl-Users-Digest
Perl-Users Digest, Issue: 2050 Volume: 10
daemon@ATHENA.MIT.EDU (Perl-Users Digest)
Thu Nov 1 18:37:16 2001
Date: Thu, 1 Nov 2001 15:10:12 -0800 (PST)
From: Perl-Users Digest <Perl-Users-Request@ruby.OCE.ORST.EDU>
To: Perl-Users@ruby.OCE.ORST.EDU (Perl-Users Digest)
Message-Id: <1004656211-v10-i2050@ruby.oce.orst.edu>
Content-Type: text
Perl-Users Digest Thu, 1 Nov 2001 Volume: 10 Number: 2050
Today's topics:
Re: newbie: error processing (Garry Williams)
Posting Guidelines for comp.lang.perl.misc ($Revision: tadmc@augustmail.com
range operator and look ahead (Brandon Metcalf)
Re: range operator and look ahead (Clinton A. Pierce)
Re: range operator and look ahead (Brandon Metcalf)
Re: range operator and look ahead (Brandon Metcalf)
Re: REGULAR EXP. HELP (abaxaba)
Re: replacing many patterns at the same time without cr <bart.lateur@skynet.be>
Re: Unsigned 8 bit math (addition and subtraction) <stuart@otenet.gr>
Re: Unsigned 8 bit math (addition and subtraction) <stuart@otenet.gr>
Re: Unsigned 8 bit math (addition and subtraction) <iltzu@sci.invalid>
Re: when does 0.58 != 0.58? <iltzu@sci.invalid>
Re: Wrapping long emails - sample code (Philip S Tellis)
Re: XL saveas doesn't work (excel) <jimbo@soundimages.co.uk>
Re: XML parsing <bart.lateur@skynet.be>
Digest Administrivia (Last modified: 6 Apr 01) (Perl-Users-Digest Admin)
----------------------------------------------------------------------
Date: Thu, 01 Nov 2001 19:23:57 GMT
From: garry@ifr.zvolve.net (Garry Williams)
Subject: Re: newbie: error processing
Message-Id: <slrn9u38ae.148.garry@zfw.zvolve.net>
On 1 Nov 2001 05:45:04 -0800, John Menke <jmenke@scsnet.csc.com> wrote:
> I would like to execute a subroutine when an error occurs in my
> script.
>
> I am familiar with die and warn, but they only seem to print to STDERR
> and I cannot call subroutines from within the die and warn statements.
>
> Is there any way to first execute a subroutine when an error occurs
> and then die or warn?
>
> Specifically, I have statements like these:
>
> or warn "Disconnection failed: $DBI::errstr\n";
>
> I would like to do this:
>
> or warn addLogMessage("this is the log message");
>
> and get the script to continue
>
> or do this:
>
> or die addLogMessage("this is the log message");
>
> and then die...
>
> is this possible?
You might be looking for this:
... or do {
addLogMessage("something bad happened");
die;
};
--
Garry Williams
------------------------------
Date: Thu, 01 Nov 2001 21:47:23 GMT
From: tadmc@augustmail.com
Subject: Posting Guidelines for comp.lang.perl.misc ($Revision: 1.2 $)
Message-Id: <LpjE7.31401$U7.2358099@bin1.nnrp.aus1.giganews.com>
Outline
Before posting to comp.lang.perl.misc
Must
- Check the Perl Frequently Asked Questions (FAQ)
- Check the other standard Perl docs (*.pod)
Really Really Should
- Lurk for a while before posting
- Search a Usenet archive
If You Like
- Check Other Resources
Posting to comp.lang.perl.misc
Is there a better place to ask your question?
- Question should be about Perl, not about the application area
How to participate (post) in the clpmisc community
- Carefully choose the contents of your Subject header
- Use an effective followup style
- Speak Perl rather than English, when possible
- Ask perl to help you
- Do not re-type Perl code
- Provide enough information
- Do not provide too much information
- Do not post binaries, HTML, or MIME
Social faux pas to avoid
- Asking a Frequently Asked Question
- Asking a question easily answered by a cursory doc search
- Asking for emailed answers
- Beware of saying "doesn't work"
- Sending a "stealth" Cc copy
Be extra cautious when you get upset
- Count to ten before composing a followup when you are upset
- Count to ten after composing and before posting when you are upset
-----------------------------------------------------------------
Posting Guidelines for comp.lang.perl.misc ($Revision: 1.2 $)
This newsgroup, commonly called clpmisc, is a technical newsgroup
intended to be used for discussion of Perl related issues (except job
postings), whether it be comments or questions.
As you would expect, clpmisc discussions are usually very technical in
nature and there are conventions for conduct in technical newsgroups
going somewhat beyond those in non-technical newsgroups.
This article describes things that you should, and should not, do to
increase your chances of getting an answer to your Perl question. It is
available in POD, HTML and plain text formats at:
http://mail.augustmail.com/~tadmc/clpmisc.shtml
For more information about netiquette in general, see the "Netiquette
Guidelines" at:
http://andrew2.andrew.cmu.edu/rfc/rfc1855.html
A note to newsgroup "regulars":
Please do not use the existence of these guidelines as a
"license to flame" or other meanness. It is possible that
a poster is not aware of the things discussed here. Let's
give them the benefit of the doubt, and just help them learn
how to post, rather than assume that they do know and are
being the "bad kind" of Lazy.
A note about technical terms used here:
In this document, we use words like "must" and "should" in the
very precise sense that they're used in technical conversation
(such as you're likely to encounter in this newsgroup). When
we say that you *must* do something, we mean that if you don't
do that something, then it's very unlikely that you're going to
get much benefit from using this group. We're not trying to boss
you around; we're just trying to convey the point without using
a lot of words.
Do *NOT* send email to the maintainer of these guidelines. It will be
discarded unread. The guidelines belong to the newsgroup so all
discussion should appear in the newsgroup. I am just the secretary that
writes down the consensus of the group.
Before posting to comp.lang.perl.misc
Must
This section describes things that you *must* do before posting to
clpmisc, in order to maximize your chances of getting meaningful replies
to your inquiry and to avoid getting flamed for being lazy and trying to
have others do your work.
The perl distribution includes documentation that is copied to your hard
drive when you install perl. Also installed is a program for looking
things up in that (and other) documentation named 'perldoc'.
You should either find out where the docs got installed on your system,
or use perldoc to find them for you. Type "perldoc perldoc" to learn how
to use perldoc itself. Type "perldoc perl" to start reading Perl's
standard documentation.
Check the Perl Frequently Asked Questions (FAQ)
Checking the FAQ before posting is required in Big 8 newsgroups in
general, there is nothing clpmisc-specific about this requirement.
You are expected to do this in nearly all newsgroups.
You can use the "-q" switch with perldoc to do a word search of the
questions in the Perl FAQs.
Check the other standard Perl docs (*.pod)
The perl distribution comes with much more documentation than is
available for most other newsgroups, so in clpmisc you should also
see if you can find an answer in the other (non-FAQ) standard docs
before posting.
It is *not* required, or even expected, that you actually *read* all of
Perl's standard docs, only that you spend a few minutes searching them
before posting.
Try doing a word-search in the standard docs for some words/phrases
taken from your problem statement or from your very carefully worded
"Subject:" header.
Really Really Should
This section describes things that you *really should* do before posting
to clpmisc.
Lurk for a while before posting
This is very important and is expected regardless of what newsgroup
you are visiting. Lurking means to simply monitor a newsgroup for a
period of time until you become very familiar with local customs.
Think of a newsgroup as foreign culture. Each newsgroup has its own
specific customs and rituals. Get to know those customs and rituals
well before you participate. This will help you to avoid
embarrassing social situations. Consider yourself to be a foreigner
at first!
Search a Usenet archive
There are tens of thousands of Perl programmers. It is very likely
that your question has already been asked (and answered). See if you
can find where it has already been answered.
One such searchable archive is:
http://groups.google.com/advanced_group_search
If You Like
This section describes things that you *can* do before posting to
clpmisc.
Check Other Resources
You may want to check in books or on web sites to see if you can
find the answer to your question.
But you need to consider the source of such information: there are a
lot of very poor Perl books and web sites, and several good ones
too, of course.
Posting to comp.lang.perl.misc
There can be 200 messages in clpmisc in a single day. Nobody is going to
read every article. They must decide somehow which articles they are
going to read, and which they will skip.
Your post is in competition with 199 other posts. You need to "win"
before a person who can help you will even read your question.
These sections describe how you can help keep your article from being
one of the "skipped" ones.
Is there a better place to ask your question?
Question should be about Perl, not about the application area
It can be difficult to separate out where your problem really is,
but you should make a conscious effort to post to the most
applicable newsgroup. That is, after all, where you are the most
likely to find the people who know how to answer your question.
Being able to "partition" a problem is an essential skill for
effectively troubleshooting programming problems. If you don't get
that right, you end up looking for answers in the wrong places.
It should be understood that you may not know that the root of your
problem is not Perl-related (the two most frequent ones are CGI and
Operating System related), so off-topic postings will happen from
time to time. Be gracious when someone helps you find a better place
to ask your question by pointing you to a more applicable newsgroup.
How to participate (post) in the clpmisc community
Carefully choose the contents of your Subject header
You have 40 precious characters of Subject to win out and be one of
the posts that gets read. Don't waste them. Take care while
composing them, they are the key that opens the door to getting an
answer.
Spend them indicating what aspect of Perl others will find if they
should decide to read your article.
Do not spend them indicating "experience level" (guru, newbie...).
Do not spend them pleading (please read, urgent, help!...).
Do not spend them on non-Subjects (Perl question, one-word
Subject...)
For more information on choosing a Subject see "Choosing Good
Subject Lines":
http://www.perl.com/CPAN-local/authors/Dean_Roehrich/subjects.post
Part of the beauty of newsgroup dynamics, is that you can contribute
to the community with your very first post! If your choice of
Subject leads a fellow Perler to find the thread you are starting,
then even asking a question helps us all.
Use an effective followup style
When composing a followup, quote only enough text to establish the
context for the comments that you will add. Always indicate who
wrote the quoted material. Never quote an entire article. Never
quote a .signature (unless that is what you are commenting on).
Intersperse your comments *following* the sections of quoted text
that your comments apply to. Failure to do this is called "Jeopardy"
posting because the answer comes before the question.
Reversing the chronology of the dialog makes it much harder to
understand (some folks won't even read it if written in that style).
For more information on quoting style, see:
http://www.geocities.com/nnqweb/nquote.html
Speak Perl rather than English, when possible
Perl is much more precise than natural language. Saying it in Perl
instead will avoid misunderstanding your question or problem.
Do not say: I have variable with "foo\tbar" in it.
Instead say: I have $var = "foo\tbar", or I have $var = 'foo\tbar',
or I have $var = <DATA> (and show the data line).
Ask perl to help you
You can ask perl itself to help you find common programming mistakes
by doing two things: enable warnings (perldoc warnings) and enable
"strict"ures (perldoc strict).
You should not bother the hundreds/thousands of readers of the
newsgroup without first seeing if a machine can help you find your
problem. It is demeaning to be asked to do the work of a machine. It
will annoy the readers of your article.
You can look up any of the messages that perl might issue to find
out what the message means and how to resolve the potential mistake
(perldoc perldiag). If you would like perl to look them up for you,
you can put "use diagnostics;" near the top of your program.
Do not re-type Perl code
Use copy/paste or your editor's "import" function rather than
attempting to type in your code. If you make a typo you will get
followups about your typos instead of about the question you are
trying to get answered.
Provide enough information
If you do the things in this item, you will have an Extremely Good
chance of getting people to try and help you with your problem!
These features are a really big bonus toward your question winning
out over all of the other posts that you are competing with.
First make a short (less than 20-30 lines) and *complete* program
that illustrates the problem you are having. People should be able
to run your program by copy/pasting the code from your article. (You
will find that doing this step very often reveals your problem
directly. Leading to an answer much more quickly and reliably than
posting to Usenet.)
Describe *precisely* the input to your program. Also provide example
input data for your program. If you need to show file input, use the
__DATA__ token (perldata.pod) to provide the file contents inside of
your Perl program.
Show the output (including the verbatim text of any messages) of
your program.
Describe how you want the output to be different from what you are
getting.
If you have no idea at all of how to code up your situation, be sure
to at least describe the 2 things that you *do* know: input and
desired output.
Do not provide too much information
Do not just post your entire program for debugging. Most especially
do not post someone *else's* entire program.
Do not post binaries, HTML, or MIME
clpmisc is a text only newsgroup. If you have images or binaries
that explain your question, put them in a publically accessible
place (like a Web server) and provide a pointer to that location. If
you include code, cut and paste it directly in the message body.
Don't attach anything to the message. Don't post vcards or HTML.
Many people (and even some Usenet servers) will automatically filter
out such messages. Many people will not be able to easily read your
post. Plain text is something everyone can read.
Social faux pas to avoid
The first two below are symptoms of lots of FAQ asking here in clpmisc.
It happens so often that folks will assume that it is happening yet
again. If you have looked but not found, or found but didn't understand
the docs, say so in your article.
Asking a Frequently Asked Question
It should be understood that you may have missed the applicable FAQ
when you checked, which is not a big deal. But if the Frequently
Asked Question is worded similar to your question, folks will assume
that you did not look at all. Don't become indignant at pointers to
the FAQ, particularly if it solves your problem.
Asking a question easily answered by a cursory doc search
If folks think you have not even tried the obvious step of reading
the docs applicable to your problem, they are likely to become
annoyed.
If you are flamed for not checking when you *did* check, then just
shrug it off (and take the answer that you got).
Asking for emailed answers
Emailed answers benefit one person. Posted answers benefit the
entire community. If folks can take the time to answer your
question, then you can take the time to go get the answer in the
same place where you asked the question.
It is OK to ask for a *copy* of the answer to be emailed, but many
will ignore such requests anyway. If you munge your address, you
should never expect (or ask) to get email in response to a Usenet
post.
Ask the question here, get the answer here (maybe).
Beware of saying "doesn't work"
This is a "red flag" phrase. If you find yourself writing that,
pause and see if you can't describe what is not working without
saying "doesn't work". That is, describe how it is not what you
want.
Sending a "stealth" Cc copy
A "stealth Cc" is when you both email and post a reply without
indicating *in the body* that you are doing so.
Be extra cautious when you get upset
Count to ten before composing a followup when you are upset
This is recommended in all Usenet newsgroups. Here in clpmisc, most
flaming sub-threads are not about any feature of Perl at all! They
are most often for what was seen as a breach of netiquette. If you
have lurked for a bit, then you will know what is expected and won't
make such posts in the first place.
But if you get upset, wait a while before writing your followup. I
recommend waiting at least 30 minutes.
Count to ten after composing and before posting when you are upset
After you have written your followup, wait *another* 30 minutes
before committing yourself by posting it. You cannot take it back
once it has been said.
AUTHOR
Tad McClellan <tadmc@augustmail.com> and many others on the
comp.lang.perl.misc newsgroup.
------------------------------
Date: 1 Nov 2001 18:53:39 GMT
From: bmetcalf@nortelnetworks.com (Brandon Metcalf)
Subject: range operator and look ahead
Message-Id: <9rs5nj$nec$1@bcarh8ab.ca.nortel.com>
I'm trying to figure out how to use the range operator (or other method)
to accomplish what the code does below in order to avoid reading the
entire file into memory at once. Basically, the code inserts a string of
text after a certain block of text but before the next block starts
indicated by the string Class.
Here's what I have so far by slurping in the whole file
{
local undef $/;
$file = <FILE_R>;
}
my $text = 'sometext'
my $str = 'somestring';
my $file =~ s/(Class $str.*?)Class/$1$text\n\nClass/gs;
What I can't figure out is how to do some sort of look ahead with the
range operator. In other words, when reading line by line is there a
way to determine that the string Class is about to come up but insert
the contents of $text before it does?
Thanks,
Brandon
------------------------------
Date: Thu, 01 Nov 2001 19:45:34 GMT
From: clintp@geeksalad.org (Clinton A. Pierce)
Subject: Re: range operator and look ahead
Message-Id: <3be1a449.189317424@localhost>
On 1 Nov 2001 18:53:39 GMT, bmetcalf@nortelnetworks.com (Brandon
Metcalf) wrote:
>What I can't figure out is how to do some sort of look ahead with the
>range operator. In other words, when reading line by line is there a
>way to determine that the string Class is about to come up but insert
>the contents of $text before it does?
Your "in other words" made more sense than the rest of your post. :)
read a line
does this contain /Class/?
if so, output $text
output the line
But the /s gives me a hint that you've got newlines in odd places in
your input file. Care to post a bit of it to let us see exactly what
you've got there? Hmm?
Another neat trick might be to use "Class" as your input record
separator. Since your substitution is just repeating it at its
current position it remains unchanged.
--
Clinton A. Pierce Teach Yourself Perl in 24 Hours *and*
clintp@geeksalad.org Perl Developer's Dictionary
"If you rush a Miracle Man, for details, see http://geeksalad.org
you get rotten Miracles." --Miracle Max, The Princess Bride
------------------------------
Date: 1 Nov 2001 19:50:42 GMT
From: bmetcalf@nortelnetworks.com (Brandon Metcalf)
Subject: Re: range operator and look ahead
Message-Id: <9rs92i$r15$1@bcarh8ab.ca.nortel.com>
bmetcalf@nortelnetworks.com writes:
> I'm trying to figure out how to use the range operator (or other method)
> to accomplish what the code does below in order to avoid reading the
> entire file into memory at once. Basically, the code inserts a string of
> text after a certain block of text but before the next block starts
> indicated by the string Class.
>
> Here's what I have so far by slurping in the whole file
>
>
> {
> local undef $/;
> $file = <FILE_R>;
> }
>
> my $text = 'sometext'
> my $str = 'somestring';
> my $file =~ s/(Class $str.*?)Class/$1$text\n\nClass/gs;
Figured it out. Something like this.
while (<FILE_R>) {
if (/Class $str/) {
$inside++;
}
if ($inside && /Class/ && !/Class $str/) {
print FILE_W $text;
print FILE_W;
undef $inside;
}
else {
print FILE_W;
}
}
Brandon
------------------------------
Date: 1 Nov 2001 21:10:39 GMT
From: bmetcalf@nortelnetworks.com (Brandon Metcalf)
Subject: Re: range operator and look ahead
Message-Id: <9rsdof$2m4$1@bcarh8ab.ca.nortel.com>
clintp@geeksalad.org writes:
> On 1 Nov 2001 18:53:39 GMT, bmetcalf@nortelnetworks.com (Brandon
> Metcalf) wrote:
> >What I can't figure out is how to do some sort of look ahead with the
> >range operator. In other words, when reading line by line is there a
> >way to determine that the string Class is about to come up but insert
> >the contents of $text before it does?
>
> Your "in other words" made more sense than the rest of your post. :)
>
> read a line
> does this contain /Class/?
> if so, output $text
> output the line
>
> But the /s gives me a hint that you've got newlines in odd places in
> your input file. Care to post a bit of it to let us see exactly what
> you've got there? Hmm?
Class interface.syn-generic
Property int _isInterface Static(1) Private
Property string[68] Label Indexed
Property string[16] IP_Address Indexed
Property string[32] MAC_Address
Property int _interface_num Private
Property int _interface_type Private
Property string[128] SegmentName Private
Property int _isDefaultInterface Private
Property long _time_stamp Private
Property int _status Private
Property string[68] DNS_Name
Property int[] MonLevel Private
Property string[32] Type Static("Interface")
Property string[32] SubType Static("")
Property int Layer Static(0) Private
Property int Status SetNotify(900) Private
Property string[32] LargeIcon Static("interface24.gif") Private
Property string[32] SmallIcon Static("interface16.gif") Private
Property int MaxStatus Indexed DefaultValue(3)
SetNotify(900) Private
Class connection.syn-physlink
...
The /s is so the gets treated as a single line.
The trick is that only certain "Class" blocks need the text inserted at
the end of that block. My followup contains a solution that requires
the use of a state variable to determine if I'm in one of those blocks.
> Another neat trick might be to use "Class" as your input record
> separator. Since your substitution is just repeating it at its
> current position it remains unchanged.
Yep, this would work too.
Brandon
------------------------------
Date: 1 Nov 2001 11:47:28 -0800
From: msanderso@hotmail.com (abaxaba)
Subject: Re: REGULAR EXP. HELP
Message-Id: <b89e0a91.0111011147.62e9a201@posting.google.com>
tvn007@hotmail.com (Tim) wrote in message news:<21724be2.0110311239.200a64c6@posting.google.com>...
> Hi,
>
> Could someone help me on this ?
>
>
> I would like to write a script that only
> print out:
>
> file.doc
> file2.doc
> file3.doc
>
> Input data:
>
> /windows/program/file.doc
> /windows/program/file2.doc
> /windows/tom/file/data/file3.doc
>
> ####################################
> I attempted to use split.
> $file = (split /\//,$_)[3];
> but I do not think it will work !!!
Try something like:
($file) = /\/([^\/]+)$/;
------------------------------
Date: Thu, 01 Nov 2001 23:00:48 GMT
From: Bart Lateur <bart.lateur@skynet.be>
Subject: Re: replacing many patterns at the same time without cross-interference
Message-Id: <tnk3ut0pv9untjtlfacftdpm8so0aal747@4ax.com>
joe dassin wrote:
>I first had something like:
>
>for ($n=0; $searched[$n]; $n++) {
> $line =~ s/($searched[$n])/
> <b style="background-color:#$color[$n]">\1<\/b>/ig;
>}
>
>which seemed to work fine, until I saw this problem:
>If the words in @searched are, say, 'pretty' and 'background',
>the second s/// will also replace the 'background' in
>'style="background-color' of the tags highlighting 'pretty',
Try something along the lines of:
# set up:
%color = map { $searched[$_] => $color[$_] } 0 .. $#searched;
# do it:
$" = '|';
$line =~ s/(@searched)/<b
style="background-color:#$color{lc $1}">$1<\/b>/ig;
Sorry about the line wrap.
Oh: you should NEVER use \1 on the Right Hand Side of the s///, unless
you intend to represent chr(1).
--
Bart.
------------------------------
Date: Thu, 1 Nov 2001 20:59:55 +0200
From: "Stuart Gall" <stuart@otenet.gr>
Subject: Re: Unsigned 8 bit math (addition and subtraction)
Message-Id: <9rs7v1$cae$1@usenet.otenet.gr>
> perldoc perlnumber
>
> > ((0-1) % 256) ahould equal -1
>
> ?!!! No it should not.
>
> > perlop says
> > Binary ``%'' computes the modulus of two numbers. Given integer operands
$a
> > and $b: If $b is positive, then $a % $b is $a minus the largest multiple
of
> > $b that is not greater than $a.
>
> This does not imply what you said.
Well thinking about it no it does not
if $a = -1 and $b=256 then the largest multiple of $b < $a is -256
so -1 - (-256) = 255
as required
--
Stuart Gall
------------------------------------------------
This message is not provable.
------------------------------
Date: Thu, 1 Nov 2001 21:22:46 +0200
From: "Stuart Gall" <stuart@otenet.gr>
Subject: Re: Unsigned 8 bit math (addition and subtraction)
Message-Id: <9rs7v1$cae$2@usenet.otenet.gr>
"Ian Boreham" <ianb@ot.com.au> wrote in message
news:f02c4576.0110312356.48d87be4@posting.google.com...
> What definition of modulus do you normally use? Normally a contiguous
> set of non-negative integers starting at zero are used, and the Perl
> implementation (and other languages I have seen) implement it that
> way. It appears to be the most logical and convenient range of
> integers to use, and without explicitly specifying a different set,
> I'm not sure how you could meaningfully use modulo arithmetic.
In mathematics if one uses the quotient remainder theorem then r is always
>=0
If we talk about modulus then it is just a question of congruency so in mod
256
-1 == 254 .
Any how I found the source of my wrong impression
#include <stdio.h>
main() {
printf("TEST = %d", (0-1) % 256);
};
Compiled using borland C
gives
TEST = -1
in C a % b is defined as " the remainder of a/b " but that dosent mean much
is it 0 remainder -1 or -1 remainder 255. Well in practice is seems the
former is used.
Then just to be realy GROSS I tried some visual basic
Sub test()
MsgBox "TEST = " & ((0 - 1) Mod 256), vbOKOnly, "result"
End Sub
Which gives -1 too in a nice little box.
Next I used mathcad
mod(-1,256) = -1
Now please NOTE WELL I am not saying that perl should do this what perl does
is much better, let the rest of the world be wrong. I am just saying that I
was justified in expecting perl to work this way because just about
everything else I have used does.
--
Stuart Gall
------------------------------------------------
This message is not provable.
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Date: 1 Nov 2001 22:41:31 GMT
From: Ilmari Karonen <iltzu@sci.invalid>
Subject: Re: Unsigned 8 bit math (addition and subtraction)
Message-Id: <1004651588.15082@itz.pp.sci.fi>
In article <9rpr5h$4r5$2@usenet.otenet.gr>, Stuart Gall wrote:
>((0-1) % 256) ahould equal -1
Allow me to disagree.
>Hmmm. I guess what perl does is more likely to be usefull to a programmer,
>like most of what perl does. But it does not follow the mathematical
>definition of modulus
Actually, what perl does is rely on the integer modulus operator of the
C compiler it was built with. This means that, in current versions of
perl, modulus is only consistently defined across different platforms
for small non-negative integers (where "small" means "less than 2**31").
The way it *should* IMO work is like this:
use POSIX 'floor';
sub modulus ($$) { $_[0] - $_[1] * floor($_[0] / $_[1]) }
This satisfies the following, IMO useful, identity:
a % b == (a+b) % b == (a-b) % b
for all reals a and b (except b = 0). It also agrees with the current
behavior for all non-negative integers, and in particular satisfies the
rule that a % b == 0 if and only if a is an integer multiple of b.
Note that this differs from the POSIX function fmod() precisely in the
sign of the result when a < 0. Thus fmod() does not satisfy the above
identity. (For example, fmod(3, 5) != fmod(3-5, 5).)
--
Ilmari Karonen -- http://www.sci.fi/~iltzu/
"Get real! This is a discussion group, not a helpdesk. You post something,
we discuss its implications. If the discussion happens to answer a question
you've asked, that's incidental." -- nobull in comp.lang.perl.misc
------------------------------
Date: 1 Nov 2001 22:54:54 GMT
From: Ilmari Karonen <iltzu@sci.invalid>
Subject: Re: when does 0.58 != 0.58?
Message-Id: <1004655087.17957@itz.pp.sci.fi>
In article <EGRD7.400$lh4.4669@newsfeeds.bigpond.com>, Gregory Toomey wrote:
>
>use POSIX;
>sub round {
> return floor($_[0]+0.5);
>}
>if (round($x*100) == round($y*100)) ...
Or, somewhat less verbosely:
if (abs($x - $y) < 0.005) ...
--
Ilmari Karonen -- http://www.sci.fi/~iltzu/
"Get real! This is a discussion group, not a helpdesk. You post something,
we discuss its implications. If the discussion happens to answer a question
you've asked, that's incidental." -- nobull in comp.lang.perl.misc
------------------------------
Date: 1 Nov 2001 11:28:58 -0800
From: philip@ncst.ernet.in (Philip S Tellis)
Subject: Re: Wrapping long emails - sample code
Message-Id: <d1eff1dd.0111011128.75b14942@posting.google.com>
Ilya Martynov <ilya@martynov.org> wrote in message news:<87ady7aa54.fsf@abra.ru>...
>
> >> > s/^((?:[>}|%]\s?)+)(\s*)//o;
> >> ^^^
> >> Why the 'o' option?
>
> Philip> Since the code runs with -p, it basically loops through every line
> Philip> of the input. The /o will compile the regex the first time, making
>
> /o - makes sense only if you pattern contain variables, which will be
> interpolated. In all other cases there is no difference.
Ah, yes. I originally had the character class [>}|%] in a variable,
so that the user of the script could set it along with $columns. In
that case, the /o would make sense.
I think I might have changed it to this form to see the difference
in performance, and never bothered to change it back. Also forgot
about the /o
Cheers,
Philip
------------------------------
Date: Thu, 1 Nov 2001 19:14:46 -0000
From: "jimbo" <jimbo@soundimages.co.uk>
Subject: Re: XL saveas doesn't work (excel)
Message-Id: <GahE7.1218$rg7.12604@NewsReader>
> xlCSV is likely an integer constant, of which, in some way, you should
> find out the value and use it.
use Win32::OLE;
use Win32::OLE::Const;
my $Excel = Win32::OLE->new('Excel.Application', 'Quit');
my $xl = Win32::OLE::Const->Load($Excel);
print $xl->{xlCSV};
jimbo
;-)
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Date: Thu, 01 Nov 2001 22:54:32 GMT
From: Bart Lateur <bart.lateur@skynet.be>
Subject: Re: XML parsing
Message-Id: <c9k3utcj5j7f4lpasgbt86j72t9nsceadp@4ax.com>
Robin Berjon wrote:
>clintp@geeksalad.org (Clinton A. Pierce) wrote in message
>> For chrissakkes: it's just text processing. I thought Perl was supposed
>> to make this stuff easy.
>
>That's where you get it blantantly wrong. XML isn't about text
>processing, it's about structure. The fact that the canonical storage
>format happens to be textual is just for convenience.
So you're an expert on XML? Wow.
"It is a floor wax and a desert topping". XML is more than a tree saved
as text. It is BOTH that, and a structured text format, as much as RTF,
HTML, or plain program source code is. "Text" is more than flat files --
"CSV" as you call it. A fact is that Perl is pretty bad for processing
structured text. Clinton Pierce is right about not being too happy about
that fact. I am neither.
--
Bart.
------------------------------
Date: 6 Apr 2001 21:33:47 GMT (Last modified)
From: Perl-Users-Request@ruby.oce.orst.edu (Perl-Users-Digest Admin)
Subject: Digest Administrivia (Last modified: 6 Apr 01)
Message-Id: <null>
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