RE: Re[2]: [PHP] One more time about regexes

2010-05-27 Thread Ford, Mike


 -Original Message-
 From: Andre Polykanine [mailto:an...@oire.org]
 Sent: 27 May 2010 09:14
 To: Adam Richardson
 Cc: php-general@lists.php.net
 Subject: Re[2]: [PHP] One more time about regexes
 
 Hello Adam,
 
 You did understand me exactly and perfectly).
 Ordering arrays is a good idea but I don't know how to do that
 exactly.
 For instance, there's a cypher called Polybius square. You write in
 the alphabet in a grid like this:
 1 a b c d e
 2 f g h i j
 3 k l m n o
 4 p q r s t
 5 u v w x y
 6 z
 
 There is a way where i/j are equal to make a 5 by 5 square but for
 me
 it's equal since I'm working with a 33-letter Russian alphabet, so
 no
 way to make it a perfect square.
 Anyway, a letter has two coordinates and is represented by a two-
 digit
 number. For example, E is 15, K is 21, Z is 61 and so on.
 So we have a word, say, PHP. It will look like this: 412341.

Well, as you're wanting to replace pairs of digits, I'd search for exactly that 
-- but I think I'd use the e flag to employ a programmed replacement, thus:

$str = 4123415 - 2444 452315 12154445!;
$replaced = preg_replace({(\d\d)}e, polybius_decode('\\1'), $str);

echo $replaced;

function polybius_decode($pair) {

   static $polybius = array(
  '11'='a', 'b', 'c', 'd', 'e',
  '21'='f', 'g', 'h', 'i', 'j',
  '31'='k', 'l', 'm', 'n', 'o',
  '41'='p', 'q', 'r', 's', 't',
  '51'='u', 'v', 'w', 'x', 'y',
  '61'='z'
   );

   return isset($polybius[$pair]) ? $polybius[$pair] : $pair;
}

Seems to work: php5 - is the best!. :)

Cheers!

Mike
 -- 
Mike Ford,
Electronic Information Developer, Libraries and Learning Innovation,  
Leeds Metropolitan University, C507, Civic Quarter Campus, 
Woodhouse Lane, LEEDS,  LS1 3HE,  United Kingdom 
Email: m.f...@leedsmet.ac.uk 
Tel: +44 113 812 4730





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Re: Re[2]: [PHP] One more time about regexes

2010-05-27 Thread Adam Richardson
On Thu, May 27, 2010 at 4:13 AM, Andre Polykanine an...@oire.org wrote:

 Hello Adam,

 You did understand me exactly and perfectly).
 Ordering arrays is a good idea but I don't know how to do that
 exactly.
 For instance, there's a cypher called Polybius square. You write in
 the alphabet in a grid like this:
 1 a b c d e
 2 f g h i j
 3 k l m n o
 4 p q r s t
 5 u v w x y
 6 z

 There is a way where i/j are equal to make a 5 by 5 square but for me
 it's equal since I'm working with a 33-letter Russian alphabet, so no
 way to make it a perfect square.
 Anyway, a letter has two coordinates and is represented by a two-digit
 number. For example, E is 15, K is 21, Z is 61 and so on.
 So we have a word, say, PHP. It will look like this: 412341.
 What does preg_replace do? Exactly, it's searching 41, then 12, then
 23, and so on.
 I tried to make a loop:
 $length=mb_strlen($str);
 for ($i=0; $i$length; $i+=2) {
 $pair=mb_substr($str, $i, 2);
 $pair=preg_replace($numbers, $letters, $str);
 }

 It already smells something not good, but anyway.
 If I do that, I have one more problem: say, we have a phrase PHP is
 the best. So we crypt it and get:
 412341 2444 452315 12154445
 Then the parser begins: 41=p, 23=h, 41=p, (attention!) \s2=
 I marked a whitespace as \s so you see what happens.
 I might split the string by spaces but I can't imagine what a user
 inputs: it might be a dash, for example...
 Sorry for such a long message but I'm really annoyed with this
 preg_replace's behavior. And it's not the only one task to
 accomplish...
 Thanks a lot!

 --
 With best regards from Ukraine,
 Andre
 Skype: Francophile; WlmMSN: arthaelon @ yandex.ru; Jabber: arthaelon @
 jabber.org
 Yahoo! messenger: andre.polykanine; ICQ: 191749952
 Twitter: m_elensule

 - Original message -
 From: Adam Richardson simples...@gmail.com
 To: php-general@lists.php.net php-general@lists.php.net
 Date: Thursday, May 27, 2010, 7:56:28 AM
 Subject: [PHP] One more time about regexes

 On Wed, May 26, 2010 at 11:10 PM, Nilesh Govindarajan li...@itech7.com
 wrote:

  -- Forwarded message --
  From: Nilesh Govindarajan li...@itech7.com
  Date: Thu, May 27, 2010 at 8:40 AM
  Subject: Re: [PHP] One more time about regexes
  To: Andre Polykanine an...@oire.org
 
 
  On Thu, May 27, 2010 at 3:33 AM, Andre Polykanine an...@oire.org
 wrote:
   Hello everyone,
  
   Sorry, but I'm asking one more time (since it's really annoying me and
   I need to apply some really dirty hacks):
   Is there a way making preg_replace() pass through the regex one single
   time searching from left to right and not to erase what it has already
   done?
   I can give you a real task I'm accomplishing but the tasks requiring
   that tend to multiply...
   Thanks a lot!
  
   --
   With best regards from Ukraine,
   Andre
   Http://oire.org/ - The Fantasy blogs of Oire
   Skype: Francophile; WlmMSN: arthaelon @ yandex.ru; Jabber: arthaelon
 @
  jabber.org
   Yahoo! messenger: andre.polykanine; ICQ: 191749952
   Twitter: http://twitter.com/m_elensule
  
  
   --
   PHP General Mailing List (http://www.php.net/)
   To unsubscribe, visit: http://www.php.net/unsub.php
  
  
 
 
  If you don't want to replace the stuff it has searched then use
 preg_match
  !
 
  --
  Nilesh Govindarajan
  Facebook: nilesh.gr
  Twitter: nileshgr
  Website: www.itech7.com
 
 
 
  --
  Nilesh Govindarajan
  Facebook: nilesh.gr
  Twitter: nileshgr
  Website: www.itech7.com
 
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 If I'm understanding correctly, Andre, you want to perform a replace
 operation, but you're observing that there's an element of recursion
 happening (e.g., you replace one item with its replacement, and then the
 new
 replacement is also replaced.)

 To my knowledge, this won't happen with a standard preg_replace():

 $string = 'Bil  Tom  Phil';
 $pattern = '//';
 $replacement = 'amp;';
 // outputs Bil amp; Tom amp; Phil
 echo preg_replace($pattern, $replacement, $string);

 However, if you're using arrays to pass in the patterns and replacements,
 then one array item could later be replaced by another (see comment and
 example on this page by info at gratisrijden dot nl):
 http://php.net/manual/en/function.preg-replace.php

 If that's the case, you have to carefully structure the order of the array
 items so-as to preclude one replacement having the opportunity to override
 a
 subsequent replacement.

 Sorry if I misunderstood.  You might want to create a simple example of
 code
 showing what you're working through.

 Adam


 --
 Nephtali:  PHP web framework that functions beautifully
 http://nephtaliproject.com


Andre,

I'd try something like this:

?php
/**
 * Description of PolybiusSquare
 *
 * @author Adam Richardson, creator of the Nephtali Web Framework
 */
class PolybiusSquare {
public $square_values;
/**
 * Creates PolybiusSquare instance for encoding and decoding