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Home: Perl Programming Help: Beginner:
Split Function

 


aksagar
New User

Feb 28, 2002, 9:12 PM

Post #1 of 15 (8397 views)
Split Function Can't Post
Hi,
I am currently analising the pre-written tool in perl. I stuck at a line which actually splits a string on some basis.Can someone explain me on what basis it is spliting a string.Attached is a piece od code contaning Split function.


$kanji = 0;
$rest = $maxrest;
@l = split(/([\001-\006\b\f\n\r\e<crlf>])/);
while (defined($w = shift(@l))) {
if ($w eq '') { next; }
if ($w eq "\f") { $bl || &nl; &rp; next; }
# formfeed
$bl && &bl;
if ($w eq "\b") { $rest++, print ' bs' if $rest < $maxrest; next; }
if ($w eq "\n") { &nl; next; }
# newline
if ($w eq "\r") { &cr; &bl; next; }
# carriage return
if ($w eq "\1") { print ' B'; next; }
# bold start
if ($w eq "\2") { print ' R'; next; }
# bold end
if ($w eq "\3") { print ' I'; next; }
# italic start
if ($w eq "\4") { print ' R'; next; }
# italic end
if ($w eq "\5") { $kanji = 1; next; }
# kanji start
if ($w eq "\6") { $kanji = 0; next; }
# kanji end
if ($w eq "\e") {
# half line/char moves
if ($l[$[] =~ s/^6//) { &half_char_back; next; }
if ($l[$[] =~ s/^7//) { &half_char_forw; next; }
if ($l[$[] =~ s/^8//) { &half_line_back; next; }
if ($l[$[] =~ s/^9//) { &half_line_forw; next; }
$w = $esc;
}


yapp
User

Mar 1, 2002, 2:28 AM

Post #2 of 15 (8386 views)
Re: [aksagar] Split Function [In reply to] Can't Post
In Reply To
@l = split(/([\001-\006\b\f\n\r\e])/);
Do this line troubles you?

split accepts a regular expression as first parameter.
The second parameter contains the script to be splitted. $_ will be used when that value is not provided. not that some lines set $_ when to variable is used to assign the value to. (like while(<FILE>)

The regular expression is actually very simple. everything between [ and ] is a character class. In other words, one of those characters should match. That is: ASCII codes 1 to 6, a \b, \f, \n (newline), \r \e
That's it.

See 'perlfaq6' and 'perlre' in the perldoc documentation for more information

Yet Another Perl Programmer

_________________________________
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More then 3500 X-Forum [url=http://www.codingdomain.com/cgi-perl/downloads/x-forum]Downloads! Cool


aksagar
New User

Mar 1, 2002, 3:06 AM

Post #3 of 15 (8381 views)
Re: [yapp] Split Function [In reply to] Can't Post
Hi ,
Thanks for the instant reply but one more thing is use of
() and [] I am not getting that thing what happens if you put characters in [] or () or like([\b\r])

Thanks once again


Paul
Enthusiast

Mar 1, 2002, 3:15 AM

Post #4 of 15 (8379 views)
Re: [aksagar] Split Function [In reply to] Can't Post
Using ( ) stores the match in the special numerical scalar, $1, $2 etc...so you could do:

$_ = 'Hello my name is Joe Bloggs';
/^(\w+)\s(\w+)/ and ($hello,$my) = ($1,$2);

[ ] are used for character classes. ie they match a range of characters eg... [a-z0-9] they also disable meta-characters. Putting a ^ at the beginning tells the regex not to match any of the characters....eg

/^[^a-z]+$/

....will match a string that doesn't have a,b,c,d,e....z


(This post was edited by RedRum on Mar 1, 2002, 3:16 AM)


freddo
User

Mar 1, 2002, 6:35 AM

Post #5 of 15 (8372 views)
Re: [aksagar] Split Function [In reply to] Can't Post
Hi Aksagar,

Still about (), when they're used in split patterns, they return the char used when splitting:[perl]$x = "1+2-3";
print join ':', split /([+-])/, $x; # 1:+:2:-:3
print join ':', split /[+-]/, $x; # 1:2:3[/perl]

'hope this helps
freddo
;---


Jasmine
Administrator / Moderator

Mar 1, 2002, 4:06 PM

Post #6 of 15 (8366 views)
Re: [aksagar] Split Function [In reply to] Can't Post
If you're curious about what /([\001-\006\b\f\n\r\e<crlf>])/ does in the split line, here's the regex, as explained by [url=http://search.cpan.org/search?dist=YAPE-Regex-Explain]YAPE::Regex::Explain

Code
  /                        '/' 
---------------------------------------------------------------------- 
  (                        group and capture to \1: 
---------------------------------------------------------------------- 
    [\001-                   any character of: '\001' to '\006', '\b' 
    \006\b\f\n\r\e<crlf>]    (backspace), '\f' (form feed), '\n' 
                             (newline), '\r' (carriage return), '\e' 
                             (escape), '<', 'c', 'r', 'l', 'f', '>' 
---------------------------------------------------------------------- 
  )                        end of \1 
---------------------------------------------------------------------- 
  /                        '/'


aksagar
New User

Mar 3, 2002, 5:41 PM

Post #7 of 15 (8351 views)
Re: [aksagar] Split Function [In reply to] Can't Post
Hi All,
Thanks for the instant help.

Best Regards,
aksagar


yapp
User

Mar 4, 2002, 8:55 AM

Post #8 of 15 (8340 views)
Re: [Jasmine] Split Function (off topic) [In reply to] Can't Post
YAPE::Regex::Explain ??

Pretty cool. I might even want to write a CGI interface for it!
Do you know anymore of those cool modules?

Yet Another Perl Programmer

_________________________________
~~> [url=http://www.codingdomain.com]www.codingdomain.com <~~
More then 3500 X-Forum [url=http://www.codingdomain.com/cgi-perl/downloads/x-forum]Downloads! Cool


Jasmine
Administrator / Moderator

Mar 4, 2002, 10:33 AM

Post #9 of 15 (8334 views)
Re: [yapp] Split Function (off topic) [In reply to] Can't Post
[url=http://search.cpan.org/search?dist=YAPE-Regex-Explain]YAPE::Regex::Explain is [ japhy ]'s baby. Here's what I use for the interface -- not pretty, but totally functional Smile

[perl]#!/usr/bin/perl

use CGI;
use YAPE::Regex::Explain;
use strict;

my $in = CGI->new();
my $regex;
my $exp;

{ local $/; chomp( $regex = $in->param('regex') ) }

print $in->header,
$in->start_html( -title => 'YAPE' ),
$in->start_form( -method => 'post'),
$in->textarea( { -cols => '60', -rows => '3', -name => 'regex' } ),
$in->submit( -value => 'Explain!' ),
$in->end_form,
$in->hr;

$exp = YAPE::Regex::Explain->new( eval "qr/\$regex/" );
$exp->parse or $exp->error and die "explain error: " . $exp->error;

print $in->pre( $exp->explain ), $in->end_html;[/perl]

edit: fixed url


(This post was edited by Jasmine on Mar 4, 2002, 7:51 PM)


Paul
Enthusiast

Mar 4, 2002, 11:47 AM

Post #10 of 15 (8330 views)
Re: [Jasmine] Split Function (off topic) [In reply to] Can't Post
No modules found matching 'YAPE-Regex-Explain'


mhx
Enthusiast / Moderator

Mar 4, 2002, 12:37 PM

Post #11 of 15 (8328 views)
Re: [RedRum] Split Function (off topic) [In reply to] Can't Post
Why? I have no problem to find [url=http://search.cpan.org/search?dist=YAPE-Regex-Explain]it at CPAN?

-- mhx
At last with an effort he spoke, and wondered to hear his own words, as if some other will was using his small voice. "I will take the Ring," he said, "though I do not know the way."

-- Frodo


Paul
Enthusiast

Mar 4, 2002, 12:39 PM

Post #12 of 15 (8326 views)
Re: [mhx] Split Function (off topic) [In reply to] Can't Post
Don't ask me Smile, I only pasted what cpan showed me Pirate


mhx
Enthusiast / Moderator

Mar 4, 2002, 12:40 PM

Post #13 of 15 (8324 views)
Re: [RedRum] Split Function (off topic) [In reply to] Can't Post
Sometimes the CPAN server acts a bit strange, I know from my own experience Tongue

-- mhx
At last with an effort he spoke, and wondered to hear his own words, as if some other will was using his small voice. "I will take the Ring," he said, "though I do not know the way."

-- Frodo


Paul
Enthusiast

Mar 4, 2002, 12:48 PM

Post #14 of 15 (8322 views)
Re: [mhx] Split Function (off topic) [In reply to] Can't Post
It is _reaaaaally_ slow, I do know that much Angelic


Jasmine
Administrator / Moderator

Mar 4, 2002, 7:53 PM

Post #15 of 15 (8314 views)
Re: [RedRum] Split Function (off topic) [In reply to] Can't Post
My bad. One of the urls in my post was wrong.

The correct url to YAPE::Regex::Explain is [url=http://search.cpan.org/search?dist=YAPE-Regex-Explain]http://search.cpan.org/search?dist=YAPE-Regex-Explain.

Fixed the broken url in my last post. Sorry 'bout that.

 
 


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