Re: regex optimization
Jeff Peng wrote:
Can the code (specially the regex) below be optimized to run faster?
#!/usr/bin/perl
for ($i=0; $i1000; $i+=1) {
open HD,index.html or die $!;
while(HD) {
print $1,\n if /href=http:\/\/(.*?)\/.* target=_blank/;
}
close HD;
}
Let me first normalize the code.
#!/usr/bin/perl
use strict;
use warnings;
my $fname = index.html;
for my $i ( 0 .. 999 ) {
open my $fh, , $fname or die $!;
while( $fh ) {
print $1,\n
if m{href=http://(.*?)/.* target=_blank};
}
close $fh;
}
So it captures hostnames out of href/target strings.
(for example only out of the first one in a line)
I would add a question mark afther the second .*, to minimize
backtracking. But that changes the meaning.
Further there is no need to open the file 1000 times, see -f seek.
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Ruud
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Re: paths that work in windows and linux + Umlaute
Andreas Moroder wrote: a clean way in perl to convert all the umlaute to ascii standard characters Text::Unidecode -- Ruud -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: perl multithreading
On Jan 5, 6:29 am, u...@stemsystems.com (Uri Guttman) wrote: ms == mud saisem mud_sai...@hotmail.com writes: ms I am trying to learn and understand multithreading but I am not sure ms why one would choose to use multithreading ? ms Could somebody please explain and perhaps provide a example. first off, IMO this isn't a good topic for the perl beginners list as threading isn't a simple thing. but here is a quick response to what you asked. threading is a form of what is called multitasking. this is needed when you need to do multiple things at the same time but some of them will be waiting on a resource (fetching a web page, accessing a database, etc). multitasking means you can usually have some work being done in your program or system at all times vs waiting around for one task to finish before starting another. there are several other ways to multitask including event loops and multiple processes. again, these are topics which are more than beginner level and should be asked at other places such as perlmonks, usenet or other mailing lists. uri -- Uri Guttman -- u...@stemsystems.com http://www.sysarch.com-- - Perl Code Review , Architecture, Development, Training, Support -- - Gourmet Hot Cocoa Mix http://bestfriendscocoa.com- That is a perfect response thanks. I will take any other questions to the suggested places. -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Please remove all references in mail archive
Hello, I am reggie kogulan. Please remove all references in beginners.perl.org. Back in 2003, I was subscribing to this list and I stopped it. I did post many messages. I want them to be removed. Because, I did not have idea, you will be posting everything on the internet. Google is able to find me. Please remove every link to my name in the mail-archive.com as soon as possible otherwise, I would have to take legal actions. www.mail-archive.com/beginners@perl.org/msg44490.html
Re: Please remove all references in mail archive
thought if this person really believes he has any expectation of privacy regarding any aspect of the internet, then i have some prime swampland in the sahara i'd love to sell him end thought good luck with that On Tue, Jan 5, 2010 at 11:16 PM, jay taylor jaytay2...@yahoo.com wrote: Hello, I am reggie kogulan. Please remove all references in beginners.perl.org. Back in 2003, I was subscribing to this list and I stopped it. I did post many messages. I want them to be removed. Because, I did not have idea, you will be posting everything on the internet. Google is able to find me. Please remove every link to my name in the mail-archive.com as soon as possible otherwise, I would have to take legal actions. www.mail-archive.com/beginners@perl.org/msg44490.html -- since this is a gmail account, please verify the mailing list is included in the reply to addresses
Re: Please remove all references in mail archive
jm wrote: thought if this person really believes he has any expectation of privacy regarding any aspect of the internet, then i have some prime swampland in the sahara i'd love to sell him end thought good luck with that Please don't feed the trolls. -- Just my 0.0002 million dollars worth, Shawn Programming is as much about organization and communication as it is about coding. I like Perl; it's the only language where you can bless your thingy. -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
double quotes are needed
Can someone tell me why I need double quotes for this to work at the line with: print $first, $second, $third\n; #!/usr/bin/perl -w $first = 0xFF; $second = 0377; $third = 0b; print $first, $second, $third\n; $answer = $first + $second + $third; print $answer\n; It only gives this output when I write double quotes print $first, $second, $third\n; 255, 255, 255 765 Mike Grove | AIX System Administrator OIT - BIO - Server Farms Division PA Department of Labor Industry 651 Boas Street Room 124 | Harrisburg, PA 17121 Phone: 717-705-2724 | Fax: 717-783-6364 AIX Hot Line 717-525-5598 | AIX Cell 717-329-0502
Re: double quotes are needed
Hi Mike! On Wednesday 06 Jan 2010 19:27:59 Grove, Michael wrote: Can someone tell me why I need double quotes for this to work at the line with: print $first, $second, $third\n; #!/usr/bin/perl -w Don't use -w. Add use strict; and use warnings;. Then fix the errors. $first = 0xFF; $second = 0377; $third = 0b; print $first, $second, $third\n; $third\n is invalid code. The \n must be placed inside a string. Regards, Shlomi Fish $answer = $first + $second + $third; print $answer\n; It only gives this output when I write double quotes print $first, $second, $third\n; 255, 255, 255 765 Mike Grove | AIX System Administrator OIT - BIO - Server Farms Division PA Department of Labor Industry 651 Boas Street Room 124 | Harrisburg, PA 17121 Phone: 717-705-2724 | Fax: 717-783-6364 AIX Hot Line 717-525-5598 | AIX Cell 717-329-0502 -- - Shlomi Fish http://www.shlomifish.org/ Interview with Ben Collins-Sussman - http://shlom.in/sussman Bzr is slower than Subversion in combination with Sourceforge. ( By: http://dazjorz.com/ ) -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: double quotes are needed
On Wed, Jan 6, 2010 at 11:27 AM, Grove, Michael migr...@state.pa.us wrote: Can someone tell me why I need double quotes for this to work at the line with: print $first, $second, $third\n; #!/usr/bin/perl -w $first = 0xFF; $second = 0377; $third = 0b; print $first, $second, $third\n; This passes a list to the print command. It's equivalent to saying... my @list = ($first, $second, $third); print @list; $answer = $first + $second + $third; print $answer\n; It only gives this output when I write double quotes print $first, $second, $third\n; 255, 255, 255 765 print $first, $second, $third\n prints a single, scalar value. -- Robert Wohlfarth
Re: double quotes are needed
On 1/6/10 Wed Jan 6, 2010 9:27 AM, Grove, Michael migr...@state.pa.us scribbled: Can someone tell me why I need double quotes for this to work at the line with: print $first, $second, $third\n; #!/usr/bin/perl -w $first = 0xFF; $second = 0377; $third = 0b; print $first, $second, $third\n; $answer = $first + $second + $third; print $answer\n; It only gives this output when I write double quotes print $first, $second, $third\n; 255, 255, 255 765 What output do you get when you do not write double quotes? I get 'Backslash found where operator expected at ...'. Is that what you get? (It helps to let us know what you are getting from your original version). The print function prints strings. The unquoted \n is not a string - it is a syntax error. If the \n is enclosed in double quotes, it will generate a newline character. Did you really mean print $first, $second, $third\n or did you mean print $first, $second, $third\n ? The former is a standalone string and does nothing. The latter will print the results as you have shown. You should put 'use strict;' at the top of your program, and remove the '-w' and replace it with 'use warnings;'. -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
RE: double quotes are needed
Thanks. Is this better? print $first, $second, $third,\n; 255, 255, 255 765 If I put the second set of quotes after the last comma, I get an error. I am only on pg 21 of Learning Perl 5th ed. I am trying as many variations of the examples just to mess around and see what happens with different characters. Mike Grove | AIX System Administrator OIT - BIO - Server Farms Division PA Department of Labor Industry 651 Boas Street Room 124 | Harrisburg, PA 17121 Phone: 717-705-2724 | Fax: 717-783-6364 AIX Hot Line 717-525-5598 | AIX Cell 717-329-0502 -Original Message- From: Shlomi Fish [mailto:shlo...@iglu.org.il] Sent: Wednesday, January 06, 2010 12:45 PM To: beginners@perl.org Cc: Grove, Michael Subject: Re: double quotes are needed Hi Mike! On Wednesday 06 Jan 2010 19:27:59 Grove, Michael wrote: Can someone tell me why I need double quotes for this to work at the line with: print $first, $second, $third\n; #!/usr/bin/perl -w Don't use -w. Add use strict; and use warnings;. Then fix the errors. $first = 0xFF; $second = 0377; $third = 0b; print $first, $second, $third\n; $third\n is invalid code. The \n must be placed inside a string. Regards, Shlomi Fish $answer = $first + $second + $third; print $answer\n; It only gives this output when I write double quotes print $first, $second, $third\n; 255, 255, 255 765 Mike Grove | AIX System Administrator OIT - BIO - Server Farms Division PA Department of Labor Industry 651 Boas Street Room 124 | Harrisburg, PA 17121 Phone: 717-705-2724 | Fax: 717-783-6364 AIX Hot Line 717-525-5598 | AIX Cell 717-329-0502 -- - Shlomi Fish http://www.shlomifish.org/ Interview with Ben Collins-Sussman - http://shlom.in/sussman Bzr is slower than Subversion in combination with Sourceforge. ( By: http://dazjorz.com/ ) -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: double quotes are needed
On Wednesday 06 Jan 2010 20:38:29 Grove, Michael wrote: Thanks. Is this better? print $first, $second, $third,\n; Yes, but you can also write it as: print $first, $second, $third\n; 255, 255, 255 765 If I put the second set of quotes after the last comma, I get an error. What do you mean by that? How are you writing it? Also, please avoid top-posting and quote my reply: http://en.wikipedia.org/wiki/Posting_style Regards, Shlomi Fish I am only on pg 21 of Learning Perl 5th ed. I am trying as many variations of the examples just to mess around and see what happens with different characters. Mike Grove | AIX System Administrator OIT - BIO - Server Farms Division PA Department of Labor Industry 651 Boas Street Room 124 | Harrisburg, PA 17121 Phone: 717-705-2724 | Fax: 717-783-6364 AIX Hot Line 717-525-5598 | AIX Cell 717-329-0502 -- - Shlomi Fish http://www.shlomifish.org/ Optimising Code for Speed - http://shlom.in/optimise Bzr is slower than Subversion in combination with Sourceforge. ( By: http://dazjorz.com/ ) -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: double quotes are needed
On 1/6/10 Wed Jan 6, 2010 10:38 AM, Grove, Michael migr...@state.pa.us scribbled: Thanks. Is this better? print $first, $second, $third,\n; I would just use: print $first, $second, $third\n; 255, 255, 255 765 If I put the second set of quotes after the last comma, I get an error. Not sure what you mean. Can you show us the exact line and the exact error you are getting? -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
RE: double quotes are needed
Thanks everyone. The one line I wrote was a mistake in quote placement for this message: print $first, $second, $third\n meant print $first, $second, $third, \n But I don't want the last comma in the output, so I wrote this with your help: #!/usr/bin/perl $first = 0xFF; $second = 0377; $third = 0b; print $first, $second, $third,\n; $answer = $first + $second + $third; print $answer\n; or is this way preferred? #!/usr/bin/perl $first = 0xFF; $second = 0377; $third = 0b; print $first, $second, $third\n; $answer = $first + $second + $third; print $answer\n; Mike Grove | AIX System Administrator OIT - BIO - Server Farms Division PA Department of Labor Industry 651 Boas Street Room 124 | Harrisburg, PA 17121 Phone: 717-705-2724 | Fax: 717-783-6364 AIX Hot Line 717-525-5598 | AIX Cell 717-329-0502 -Original Message- From: Shlomi Fish [mailto:shlo...@iglu.org.il] Sent: Wednesday, January 06, 2010 1:48 PM To: beginners@perl.org Cc: Grove, Michael Subject: Re: double quotes are needed On Wednesday 06 Jan 2010 20:38:29 Grove, Michael wrote: Thanks. Is this better? print $first, $second, $third,\n; Yes, but you can also write it as: print $first, $second, $third\n; 255, 255, 255 765 If I put the second set of quotes after the last comma, I get an error. What do you mean by that? How are you writing it? Also, please avoid top-posting and quote my reply: http://en.wikipedia.org/wiki/Posting_style Regards, Shlomi Fish I am only on pg 21 of Learning Perl 5th ed. I am trying as many variations of the examples just to mess around and see what happens with different characters. Mike Grove | AIX System Administrator OIT - BIO - Server Farms Division PA Department of Labor Industry 651 Boas Street Room 124 | Harrisburg, PA 17121 Phone: 717-705-2724 | Fax: 717-783-6364 AIX Hot Line 717-525-5598 | AIX Cell 717-329-0502 -- - Shlomi Fish http://www.shlomifish.org/ Optimising Code for Speed - http://shlom.in/optimise Bzr is slower than Subversion in combination with Sourceforge. ( By: http://dazjorz.com/ ) -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
RE: double quotes are needed
Shlomi, what is top posting? where you said: please avoid top-posting and quote my reply Fyi I used use strict; and use warnings; And got a bunch of global errors to I put my in front of all of my variables. I have a lot to learn still. #!/usr/bin/perl use strict; use warnings; my $first = 0xFF; my $second = 0377; my $third = 0b; print $first, $second, $third\n; my $answer = $first + $second + $third; print $answer\n; Mike Grove | AIX System Administrator OIT - BIO - Server Farms Division PA Department of Labor Industry 651 Boas Street Room 124 | Harrisburg, PA 17121 Phone: 717-705-2724 | Fax: 717-783-6364 AIX Hot Line 717-525-5598 | AIX Cell 717-329-0502 -Original Message- From: Shlomi Fish [mailto:shlo...@iglu.org.il] Sent: Wednesday, January 06, 2010 1:48 PM To: beginners@perl.org Cc: Grove, Michael Subject: Re: double quotes are needed On Wednesday 06 Jan 2010 20:38:29 Grove, Michael wrote: Thanks. Is this better? print $first, $second, $third,\n; Yes, but you can also write it as: print $first, $second, $third\n; 255, 255, 255 765 If I put the second set of quotes after the last comma, I get an error. What do you mean by that? How are you writing it? Also, please avoid top-posting and quote my reply: http://en.wikipedia.org/wiki/Posting_style Regards, Shlomi Fish I am only on pg 21 of Learning Perl 5th ed. I am trying as many variations of the examples just to mess around and see what happens with different characters. Mike Grove | AIX System Administrator OIT - BIO - Server Farms Division PA Department of Labor Industry 651 Boas Street Room 124 | Harrisburg, PA 17121 Phone: 717-705-2724 | Fax: 717-783-6364 AIX Hot Line 717-525-5598 | AIX Cell 717-329-0502 -- - Shlomi Fish http://www.shlomifish.org/ Optimising Code for Speed - http://shlom.in/optimise Bzr is slower than Subversion in combination with Sourceforge. ( By: http://dazjorz.com/ ) -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
RE: double quotes are needed
Ok, this is my final draft. Though it is syntactically correct, is it a good way to assign variables? #!/usr/bin/perl use strict; use warnings; my $first = 0xFF; my $second = 0377; my $third = 0b; my $answer = $first + $second + $third; print $first, $second, $third\n; print $answer\n; Mike Grove | AIX System Administrator OIT - BIO - Server Farms Division PA Department of Labor Industry 651 Boas Street Room 124 | Harrisburg, PA 17121 Phone: 717-705-2724 | Fax: 717-783-6364 AIX Hot Line 717-525-5598 | AIX Cell 717-329-0502 -Original Message- From: Shlomi Fish [mailto:shlo...@iglu.org.il] Sent: Wednesday, January 06, 2010 1:48 PM To: beginners@perl.org Cc: Grove, Michael Subject: Re: double quotes are needed On Wednesday 06 Jan 2010 20:38:29 Grove, Michael wrote: Thanks. Is this better? print $first, $second, $third,\n; Yes, but you can also write it as: print $first, $second, $third\n; 255, 255, 255 765 If I put the second set of quotes after the last comma, I get an error. What do you mean by that? How are you writing it? Also, please avoid top-posting and quote my reply: http://en.wikipedia.org/wiki/Posting_style Regards, Shlomi Fish I am only on pg 21 of Learning Perl 5th ed. I am trying as many variations of the examples just to mess around and see what happens with different characters. Mike Grove | AIX System Administrator OIT - BIO - Server Farms Division PA Department of Labor Industry 651 Boas Street Room 124 | Harrisburg, PA 17121 Phone: 717-705-2724 | Fax: 717-783-6364 AIX Hot Line 717-525-5598 | AIX Cell 717-329-0502 -- - Shlomi Fish http://www.shlomifish.org/ Optimising Code for Speed - http://shlom.in/optimise Bzr is slower than Subversion in combination with Sourceforge. ( By: http://dazjorz.com/ ) -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: double quotes are needed
Hi! On Wednesday 06 Jan 2010 21:10:16 Grove, Michael wrote: Shlomi, what is top posting? where you said: please avoid top-posting and quote my reply Please see: http://en.wikipedia.org/wiki/Posting_style . I gave you that link in my reply. Regards, Shlomi Fish -- - Shlomi Fish http://www.shlomifish.org/ Parody on The Fountainhead - http://shlom.in/towtf Bzr is slower than Subversion in combination with Sourceforge. ( By: http://dazjorz.com/ ) -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: regex optimization
Dr.Ruud wrote:
Jeff Peng wrote:
Can the code (specially the regex) below be optimized to run faster?
#!/usr/bin/perl
for ($i=0; $i1000; $i+=1) {
open HD,index.html or die $!;
while(HD) {
print $1,\n if /href=http:\/\/(.*?)\/.* target=_blank/;
}
close HD;
}
Let me first normalize the code.
#!/usr/bin/perl
use strict;
use warnings;
my $fname = index.html;
for my $i ( 0 .. 999 ) {
open my $fh, , $fname or die $!;
while( $fh ) {
print $1,\n
if m{href=http://(.*?)/.* target=_blank};
}
close $fh;
}
So it captures hostnames out of href/target strings.
(for example only out of the first one in a line)
I would add a question mark afther the second .*, to minimize
backtracking. But that changes the meaning.
Further there is no need to open the file 1000 times, see -f seek.
And for the sake of argument, the regex at best makes
assumptions about what's in index.html, at worst, it
gives incorrect results, e.g., from the following:
html
a href=http://www.amazon.com/;Amazon/a a
href=http://www.google.com/; target=_blankGoogle/a
/html
I would assume from the regex that google's address
is the one the user wants, but amazon's is what he
will get.
Before going to the trouble of optimizing for speed,
I think it would be best to optimize for correctness
first. :-)
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Brad
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Re: paths that work in windows and linux + Umlaute
JWK 5) It is Perl4 code from 8 years ago. that code is an abomination. one quick bug is the GetDir recursive descent sub to get all dirs doesn't check for symlinks so it can easily fall into an infinite recursion. the abuse of undef() is beyond bad nor needed. and as john said, it is perl4 code which means it is about 15 years old. it should never be installed or used anywhere. also it says it is for winblows activestate perl so it would never be easily ported to unix as it assumes \ everywhere for dir separators. also most/all of it is available in portable modules on cpan. it seems to more interested in integrating into some winblows gui toy than doing real work. so if you want to learn good perl code, look at that and see what really BAD perl code is like. especially bad perl4 code. uri Hello, I did not ask because I want to learn perl, but because I need the functionality of this application. I did not find anything else that does a similar job. Bye and thank you Andreas -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: paths that work in windows and linux + Umlaute
AM == Andreas Moroder andreas.moro...@sb-brixen.it writes: JWK 5) It is Perl4 code from 8 years ago. that code is an abomination. one quick bug is the GetDir recursive descent sub to get all dirs doesn't check for symlinks so it can easily fall into an infinite recursion. the abuse of undef() is beyond bad nor needed. and as john said, it is perl4 code which means it is about 15 years old. it should never be installed or used anywhere. also it says it is for winblows activestate perl so it would never be easily ported to unix as it assumes \ everywhere for dir separators. also most/all of it is available in portable modules on cpan. it seems to more interested in integrating into some winblows gui toy than doing real work. so if you want to learn good perl code, look at that and see what really BAD perl code is like. especially bad perl4 code. AM I did not ask because I want to learn perl, but because I need the AM functionality of this application. I did not find anything else that AM does a similar job. then why did you ask here, on a list aimed at teaching perl to beginners? this is not the place to ask for help on how to fix horrible old perl4 code. and you don't seem to get it, that code is nasty and bugridden. you haven't even tried to write your own modern code for it. most of it (from my painful but fast scan) can be done with a few common cpan modules. uri -- Uri Guttman -- u...@stemsystems.com http://www.sysarch.com -- - Perl Code Review , Architecture, Development, Training, Support -- - Gourmet Hot Cocoa Mix http://bestfriendscocoa.com - -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: regex optimization
On Jan 5, 12:13 am, moonb...@gmail.com (Erez Schatz) wrote: 2010/1/5 Jeff Peng jeffp...@netzero.net: ... This is something that Perl (post version 5.6) does inherently, which is compiling a regex only once as long as the pattern isn't modified. Prior to 5.6 you'd need to use the /o modifier ( m/href=http:\/\/(.*?)\/.* target=_blank/o ). Um no. The /o modifer stops re-compilation only if the regex needs to interpolate a variable. Otherwise, /o has no effect. Perl, has always AFAIK, cached regex compilations for re-use if there aren't variable interpolations since then the regex can't possibly change. -- Charles DeRykus -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: paths that work in windows and linux + Umlaute
AM I did not ask because I want to learn perl, but because I need the AM functionality of this application. I did not find anything else that AM does a similar job. then why did you ask here, on a list aimed at teaching perl to beginners? this is not the place to ask for help on how to fix horrible old perl4 code. and you don't seem to get it, that code is nasty and bugridden. you haven't even tried to write your own modern code for it. most of it (from my painful but fast scan) can be done with a few common cpan modules. uri Hello, my answer was not clear. Sure I want to lern pearl, ( I already wrote a few small scripts ). I did not understand that the code is so bad so I tried to clean it up a little bit to get the work done. Now you say that this could be done with a few cpan modules. Here my begginers question: could you please tell me what are the right modules to use ? Sorry and thank you Andreas -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
