[19241] in Perl-Users-Digest
Perl-Users Digest, Issue: 1436 Volume: 10
daemon@ATHENA.MIT.EDU (Perl-Users Digest)
Fri Aug 3 14:10:33 2001
Date: Fri, 3 Aug 2001 11:10:10 -0700 (PDT)
From: Perl-Users Digest <Perl-Users-Request@ruby.OCE.ORST.EDU>
To: Perl-Users@ruby.OCE.ORST.EDU (Perl-Users Digest)
Message-Id: <996862210-v10-i1436@ruby.oce.orst.edu>
Content-Type: text
Perl-Users Digest Fri, 3 Aug 2001 Volume: 10 Number: 1436
Today's topics:
Re: Q:Of negative numbers and logical operations nobull@mail.com
Re: Regex library? <yf32@cornell.edu>
Re: Regex library? (Andrew Hutchinson)
Re: Regex library? nobull@mail.com
Re: Regular Expression <jlavine@mitre.org>
Re: Regular Expression <jlavine@mitre.org>
Re: Regular Expression (John J. Trammell)
Re: Setting DOS Variables (Was: Matt Wrights formmail a <jcook@strobedata.com>
Re: Strange behavior? (Yves Orton)
Understanding parsers (David Wall)
Digest Administrivia (Last modified: 6 Apr 01) (Perl-Users-Digest Admin)
----------------------------------------------------------------------
Date: 03 Aug 2001 17:14:29 +0100
From: nobull@mail.com
Subject: Re: Q:Of negative numbers and logical operations
Message-Id: <u94rrpxgre.fsf@wcl-l.bham.ac.uk>
"Rami Saarinen" <rs55862@nospamyahoo.com> writes:
> Subject: Q:Of negative numbers and logical operations
Excellent subject line! Clear, concise, informative, keyword-rich.
> I'm converting an old C-code to perl and I ran to the following problem:
> In one point I need to run three variables throught exclusive or (^) and in
> the process I end up having a wrong result if a negative (original) value
> was involved. I think this has something to do with the (bit) sizes of
> variables (i.e. in C the variable is long integer (32 bit) and something else
> in perl) thus instead of marking the negative number the first bit is
> translated as a number. Or something...
Perl's bitwise integer operation use (by default) the unsigned version
of your architecture's integer type (as described in "perldoc perlop").
> Is there any easy way to correct this? Any kind of advice is appreciated.
use integer; # All arithmetic operations to use architecture's signed int
It's not explicitly mentioned in "perldoc integer" (it is in "perldoc
perlop"), but a side-effect of "use integer" is to change the bitwise
integer operations from unsigned to signed.
"use integer" can have nasty side effects if you give it two wide a
scope so limit its scope to just those statements where you are
performing bitwise operations that you require to be using signed
integers.
--
\\ ( )
. _\\__[oo
.__/ \\ /\@
. l___\\
# ll l\\
###LL LL\\
------------------------------
Date: Fri, 3 Aug 2001 11:24:15 -0400
From: "Young C. Fan" <yf32@cornell.edu>
Subject: Re: Regex library?
Message-Id: <9kefne$s9a$1@news01.cit.cornell.edu>
"Mik Mifflin" <NOSPAM.dogansmoobs@ctel.net> wrote in message
news:tmlf9ssmdt26f@corp.supernews.com...
> Just be a smart ass and call the perl script from the c program. That'll
> solve it. I see no reason it would have to be in c/c++. If speed really
> matters that much, then then you can turn your perl script into C source
> and compile it (I believe). I have found that redoing something in C or
> C++ takes too much time and effort, and the rewards are not that great
> compared to Perl.
I guess I could call Perl from the C program. But I'm writing a Windows
program (yeah, I know) that has to talk to Internet Explorer, so I can't
expect users to have Perl on their machine -- which is why I can't just do
it in Perl. Also, I'm very new to Windows programming and know that there
are far more relevant C++ examples available than there are in Perl.
It would just be tidier (I'm in a rush) if I could use a regex library
written for C/C++ -- is there one that does what I need (substitutions
supporting backreferences, and /sgie modifers)? I've tried posting to
comp.lang.c++ but have not gotten replies yet.
>
> - Mik Mifflin
> Dogansmoobs at ctel dot net
>
> Young C. Fan wrote:
>
> > Hi,
> >
> > I was writing a regex-heavy Perl script, but I've been told to rewrite
it
> > in C/C++. The problem is that I'm having a lot of trouble finding a
regex
> > library which supports regular expressions as well as Perl does.
> >
> > I need the library to support the following:
> >
> > - substitutions with the /s, /g, /i, and especially the /e modifiers,
with
> > support for backreferences.
> >
> > If anyone here knows of any such regex library, can you please let me
> > know? Thank you so much.
> >
> > Young
> >
> >
> >
------------------------------
Date: Fri, 03 Aug 2001 15:30:37 GMT
From: andrew.hutchinson@mcmail.vanderbilt.edu (Andrew Hutchinson)
Subject: Re: Regex library?
Message-Id: <3b6ac30c.85312406@news.vanderbilt.edu>
You could get the Perl Developer's Kit (PDK), which has a utility that
will convert a Perl script to a Win32 .exe (with the interpreter
wrapped up in the executable) that can be run on any Windows machine.
I would also point out to the c/c++ proponent that the Perl's regex
engine is faster even than egrep, which is compiled c.
On Fri, 3 Aug 2001 11:24:15 -0400, "Young C. Fan" <yf32@cornell.edu>
wrote:
>"Mik Mifflin" <NOSPAM.dogansmoobs@ctel.net> wrote in message
>news:tmlf9ssmdt26f@corp.supernews.com...
>> Just be a smart ass and call the perl script from the c program. That'll
>> solve it. I see no reason it would have to be in c/c++. If speed really
>> matters that much, then then you can turn your perl script into C source
>> and compile it (I believe). I have found that redoing something in C or
>> C++ takes too much time and effort, and the rewards are not that great
>> compared to Perl.
>
>I guess I could call Perl from the C program. But I'm writing a Windows
>program (yeah, I know) that has to talk to Internet Explorer, so I can't
>expect users to have Perl on their machine -- which is why I can't just do
>it in Perl. Also, I'm very new to Windows programming and know that there
>are far more relevant C++ examples available than there are in Perl.
>
>It would just be tidier (I'm in a rush) if I could use a regex library
>written for C/C++ -- is there one that does what I need (substitutions
>supporting backreferences, and /sgie modifers)? I've tried posting to
>comp.lang.c++ but have not gotten replies yet.
>
>>
>> - Mik Mifflin
>> Dogansmoobs at ctel dot net
>>
>> Young C. Fan wrote:
>>
>> > Hi,
>> >
>> > I was writing a regex-heavy Perl script, but I've been told to rewrite
>it
>> > in C/C++. The problem is that I'm having a lot of trouble finding a
>regex
>> > library which supports regular expressions as well as Perl does.
>> >
>> > I need the library to support the following:
>> >
>> > - substitutions with the /s, /g, /i, and especially the /e modifiers,
>with
>> > support for backreferences.
>> >
>> > If anyone here knows of any such regex library, can you please let me
>> > know? Thank you so much.
>> >
>> > Young
>> >
>> >
>> >
>
>
------------------------------
Date: 03 Aug 2001 17:15:15 +0100
From: nobull@mail.com
Subject: Re: Regex library?
Message-Id: <u93d79xgq4.fsf@wcl-l.bham.ac.uk>
"Young C. Fan" <yf32@cornell.edu> writes:
> I was writing a regex-heavy Perl script, but I've been told to rewrite it in
> C/C++.
Why? This is not a flippant question. Knowing why you have been
asked to do this is a very important part of knowing what you are
really being asked to do.
> The problem is that I'm having a lot of trouble finding a regex
> library which supports regular expressions as well as Perl does.
What happend when you typed "perl regex library" into a search engine?
For example the first hit from Google was "PCRE (Perl-compatible Regex
library) 3.1" which seems close to what you want.
> I need the library to support the following:
>
> - substitutions with the /s, /g, /i, and especially the /e modifiers, with
> support for backreferences.
If you need something that supports execution of arbitrary Perl code
(/e) then AFAIK then there's only libperl (see perldoc perlembed).
--
\\ ( )
. _\\__[oo
.__/ \\ /\@
. l___\\
# ll l\\
###LL LL\\
------------------------------
Date: Fri, 03 Aug 2001 11:45:36 -0400
From: Jeremy Lavine <jlavine@mitre.org>
Subject: Re: Regular Expression
Message-Id: <3B6AC720.250B8E9C@mitre.org>
or:
if($inputLn =~ /^\d*$/) {print "digits only"}
else {print "not just digits"}
- Jeremy Lavine
Lee Osborne wrote:
>
> Hi all,
>
> OK heres a solution!
>
> $input = "12a3456";
>
> $idLengthIn = length($input);
>
> if ($input{'document_id'} =~ /\d{$idLengthIn}/) {
>
> print "Digits ONLY!";
>
> }
>
> else {
>
> print "Not just digits!";
>
> }
>
> Lee.
>
> "Lee Osborne" <osbornelee@hotmail.com> wrote in message
> news:996079173.11940.0.nnrp-01.c2de1f0e@news.demon.co.uk...
> > Hi all,
> >
> > Sorry to bother you all but I can't find a solution to a simple problem. I
> > assure you I have had a good look for the solution, but have had no
> success.
> >
> > What is the regular expresssion to check whether a string contains ONLY
> > numbers?
> >
> > It will be part of the code:
> >
> > if ($stringIn =~ /<THE RE SOLUTION>/) {
> >
> > # Numbers only in this string}
> > else {
> >
> > # There are characters other than number in the string.
> > }
> >
> > Thanks in advance,
> >
> > Lee.
> >
> >
------------------------------
Date: Fri, 03 Aug 2001 11:45:49 -0400
From: Jeremy Lavine <jlavine@mitre.org>
Subject: Re: Regular Expression
Message-Id: <3B6AC72D.AE9113B2@mitre.org>
or:
if($inputLn =~ /^\d*$/) {print "digits only"}
else {print "not just digits"}
- Jeremy Lavine
Lee Osborne wrote:
>
> Hi all,
>
> OK heres a solution!
>
> $input = "12a3456";
>
> $idLengthIn = length($input);
>
> if ($input{'document_id'} =~ /\d{$idLengthIn}/) {
>
> print "Digits ONLY!";
>
> }
>
> else {
>
> print "Not just digits!";
>
> }
>
> Lee.
>
> "Lee Osborne" <osbornelee@hotmail.com> wrote in message
> news:996079173.11940.0.nnrp-01.c2de1f0e@news.demon.co.uk...
> > Hi all,
> >
> > Sorry to bother you all but I can't find a solution to a simple problem. I
> > assure you I have had a good look for the solution, but have had no
> success.
> >
> > What is the regular expresssion to check whether a string contains ONLY
> > numbers?
> >
> > It will be part of the code:
> >
> > if ($stringIn =~ /<THE RE SOLUTION>/) {
> >
> > # Numbers only in this string}
> > else {
> >
> > # There are characters other than number in the string.
> > }
> >
> > Thanks in advance,
> >
> > Lee.
> >
> >
------------------------------
Date: 03 Aug 2001 16:05:21 GMT
From: trammell@bayazid.hypersloth.invalid (John J. Trammell)
Subject: Re: Regular Expression
Message-Id: <slrn9ml15k.464.trammell@haqq.hypersloth.net>
On Fri, 03 Aug 2001 11:45:49 -0400, Jeremy Lavine jeopary-posted:
[jeopardectomized]
>> "Lee Osborne" wrote:
[snip]
>>> What is the regular expresssion to check whether a string contains ONLY
>>> numbers?
>
> if($inputLn =~ /^\d*$/) {print "digits only"}
> else {print "not just digits"}
>
How about:
if ($input =~ /\D/) {
print "matched a non-digit\n";
} else {
print "failed to match a non-digit\n";
}
--
Aren't you, at this point, cutting down a California Redwood using a
banana *and* a particle accelerator?
- Bernard El-Hagin, in CLPM
------------------------------
Date: 03 Aug 2001 16:08:02 GMT
From: Jim Cook <jcook@strobedata.com>
Subject: Re: Setting DOS Variables (Was: Matt Wrights formmail alert)
Message-Id: <3B6ACC61.E66E40A7@strobedata.com>
> > > The concept here, inspired by an article, is to set
> > > a DOS environmental variable and have it "stick" even
> > > after a Perl script closes. Otherwords, you could start
> > > another script and access this variable; behavior just
> > > like a proper .bat DOS file.
I apologize for posting C code here. If it is terribly bad form, let me
know and I'll not do it again. I don't know how to do just the same
thing in Perl (snoop through memory).
The following snippet is something I used in DOS in 1992. This finds the
primary command.com. The environment segment then has the stuff you can
poke around in. I wrote my own "set" program so I could do stuff like
"set a=1+1" to get the same as "set a=2".
None of this works under NT, since the 16-bit app gets VDMmed and I only
fiddle my own virtual space. Maybe this will give you something else to
waste time with ... er ... play with.
struct mcb_struct {
byte end_flag; // M or Z
word owner;
word size;
byte resv1[11];
};
struct mcb_struct _far *mcb;
void find_mcb(void)
{
mcb = NULL;
while (mcb->end_flag != 'M' || mcb->owner != FP_SEG(mcb) + 1
FP_SEG(mcb)++;
}
struct psp_struct {
word int20_term; // INT 20 termination
addr
word eom_seg; // End of mem alloc
block
byte resv1;
byte resv2[5]; // CALL FAR to DOS
function
void (_interrupt _far *INT22)(); // INT 22 terminate addr
void (_interrupt _far *INT23)(); // INT 23 Ctrl-Break
void (_interrupt _far *INT24)(); // INT 24 Critical error
word parent_psp; // Parent PSP segment
byte handle[20]; // FF = available
word environment; // Environment segment
lword resv3;
word handle_size; // Sizeof handle[]
byte _far *handle_table; // Handle address
byte resv4[23];
word CD21; // INT 21 DOS call
byte ret_far; // RET FAR
byte resv5[9];
byte fcb1[16]; // Unopened FCB #1 (uses
[36])
byte fcb2[20]; // Unopened FCB #1
byte cli_length; // Length of parameters
byte cli[127]; // Starts blank, ends CR
};
void show_psp(void)
{
struct psp_struct _far *psp;
char _far *cli;
psp = NULL;
FP_SEG(psp) = mcb->owner;
if (mcb->owner == psp->parent_psp) {
depth++;
}
cli = &psp->cli[0];
printf("%04X ", psp->parent_psp);
if (psp->environment != 0 && psp->environment != 0xFFFF) {
printf("%04X ", psp->environment);
cli = NULL;
FP_SEG(cli) = psp->environment;
while (cli[0] != '\0' || cli[1] != '\0')
cli++;
cli += 2 + sizeof(int);
if (cli[1] == ':')
printf("%Fs ", cli);
}
}
--
jcook@strobedata.com Live Honourably 4/1 - 4/3 + 4/5 - 4/7 + . . .
2001 Wed: Feb/last 4/4 6/6 8/8/ 10/10 12/12 9/5 5/9 7/11 11/7 3/14
Strobe Data Inc. home page http://www.strobedata.com
My home page O- http://jcook.net
------------------------------
Date: 3 Aug 2001 11:03:24 -0700
From: demerphq@hotmail.com (Yves Orton)
Subject: Re: Strange behavior?
Message-Id: <74f348f7.0108031003.7a45e1bb@posting.google.com>
anno4000@lublin.zrz.tu-berlin.de (Anno Siegel) wrote in message news:<9ke97p$58c$3@mamenchi.zrz.TU-Berlin.DE>...
> According to Roman Khutkyy <sky@mail.lviv.ua>:
> > Pardon...... $try{22}
>
> Still nonsense.
>
> Anno
Actually Anno its not nonsense. For some reason all of the following
are the same. This is a semi-bug in perl apparently that probably
wont be fixed (or so I have been told) as many scripts would break.
Try this:
#!perl
use strict;
use warnings;
my %hash=(key=>'value');
my $r_hash=\%hash;
print $hash{key} ."\n"; # standard
print $r_hash->{key}."\n"; # standard reference
print %hash->{key} ."\n"; # should not work but does
__END__
And you should get:
------OUTPUT--------
value
value
value
------END OUTPUT----
as output.
If you do a search in CLPM for the subject "Why does this hash work?
%h->{a}='v'" you will see a minor discussion about this issue.
Cheers,
Yves
------------------------------
Date: Fri, 03 Aug 2001 16:53:59 -0000
From: darkon@one.net (David Wall)
Subject: Understanding parsers
Message-Id: <Xns90F282ED88855darkononenet@207.126.101.97>
I've been trying to learn how to use modules such as HTML::Parser and
Parse::RecDescent, but I think I lack the background to completely
understand the documentation. Should I get a book or two from the
comp.compilers FAQ, or are there other references I should read first?
URLs are ok, but I generally prefer books that I can read at leisure.
--
David Wall
darkon@one.net
------------------------------
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>
Administrivia:
The Perl-Users Digest is a retransmission of the USENET newsgroup
comp.lang.perl.misc. For subscription or unsubscription requests, send
the single line:
subscribe perl-users
or:
unsubscribe perl-users
to almanac@ruby.oce.orst.edu.
To submit articles to comp.lang.perl.announce, send your article to
clpa@perl.com.
To request back copies (available for a week or so), send your request
to almanac@ruby.oce.orst.edu with the command "send perl-users x.y",
where x is the volume number and y is the issue number.
For other requests pertaining to the digest, send mail to
perl-users-request@ruby.oce.orst.edu. Do not waste your time or mine
sending perl questions to the -request address, I don't have time to
answer them even if I did know the answer.
------------------------------
End of Perl-Users Digest V10 Issue 1436
***************************************
