Re[6]: [PHP] preg_replace: avoiding double replacements
Ash, Actually it's not the Caesar cypher itself (see http://en.wikipedia.org/wiki/Temurah_(Kabbalah), third method), but your way of transformation seems to me the best for a while) Thanks! -- 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: Ashley Sheridan a...@ashleysheridan.co.uk To: Peter Lind peter.e.l...@gmail.com Date: Tuesday, May 18, 2010, 2:32:11 PM Subject: [PHP] preg_replace: avoiding double replacements On Tue, 2010-05-18 at 13:09 +0200, Peter Lind wrote: On 18 May 2010 12:35, Andre Polykanine an...@oire.org wrote: Hello Peter, Hm... I see I need to specify what I'm really doing. Actually, I need to change the letters in the text. It's a famous and ancient crypting method: you divide the alphabet making two parts, then you change the letters of one part with letters for other part (so A becomes N, B becomes O, etc., and vice versa). it works fine and slightly with strtr or str_replace... but only if the text is not in utf-8 and it doesn't contain any non-English letters such as Cyrillic what I need. What my regex does is the following: it sees an A, well it changes it to N; then it goes through the string and sees an N... what does it do? Surely, it changes it back to A! I hoped (in vain) that there exists a modifier preventing this behavior... but it seems that it's false( Thanks! Hmmm, what comes to mind is using your string as an array and translating one character after another, building your output string using a lookup table. Not entirely sure how that will play with utf8 characters, you'd have to try and see. I don't think you'll get any of PHPs string functions to do the work for you - they'll do the job in serial, not parallel. Regards Peter -- hype WWW: http://plphp.dk / http://plind.dk LinkedIn: http://www.linkedin.com/in/plind Flickr: http://www.flickr.com/photos/fake51 BeWelcome: Fake51 Couchsurfing: Fake51 /hype If you're wanting to use the Caesar cypher (for that's what it is) then why not just modify the entire string, character by character, to use a character code n characters ahead. For example, a capital A is ascii 65, you want to change it to an N to add 14 to that. Just keep n the same throughout and it's easy to convert back. Thanks, Ash http://www.ashleysheridan.co.uk -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
Re: Re[6]: [PHP] preg_replace: avoiding double replacements
On Wed, 2010-05-19 at 16:40 +0300, Andre Polykanine wrote: Ash, Actually it's not the Caesar cypher itself (see http://en.wikipedia.org/wiki/Temurah_(Kabbalah), third method), but your way of transformation seems to me the best for a while) Thanks! -- 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: Ashley Sheridan a...@ashleysheridan.co.uk To: Peter Lind peter.e.l...@gmail.com Date: Tuesday, May 18, 2010, 2:32:11 PM Subject: [PHP] preg_replace: avoiding double replacements On Tue, 2010-05-18 at 13:09 +0200, Peter Lind wrote: On 18 May 2010 12:35, Andre Polykanine an...@oire.org wrote: Hello Peter, Hm... I see I need to specify what I'm really doing. Actually, I need to change the letters in the text. It's a famous and ancient crypting method: you divide the alphabet making two parts, then you change the letters of one part with letters for other part (so A becomes N, B becomes O, etc., and vice versa). it works fine and slightly with strtr or str_replace... but only if the text is not in utf-8 and it doesn't contain any non-English letters such as Cyrillic what I need. What my regex does is the following: it sees an A, well it changes it to N; then it goes through the string and sees an N... what does it do? Surely, it changes it back to A! I hoped (in vain) that there exists a modifier preventing this behavior... but it seems that it's false( Thanks! Hmmm, what comes to mind is using your string as an array and translating one character after another, building your output string using a lookup table. Not entirely sure how that will play with utf8 characters, you'd have to try and see. I don't think you'll get any of PHPs string functions to do the work for you - they'll do the job in serial, not parallel. Regards Peter -- hype WWW: http://plphp.dk / http://plind.dk LinkedIn: http://www.linkedin.com/in/plind Flickr: http://www.flickr.com/photos/fake51 BeWelcome: Fake51 Couchsurfing: Fake51 /hype If you're wanting to use the Caesar cypher (for that's what it is) then why not just modify the entire string, character by character, to use a character code n characters ahead. For example, a capital A is ascii 65, you want to change it to an N to add 14 to that. Just keep n the same throughout and it's easy to convert back. Thanks, Ash http://www.ashleysheridan.co.uk http://en.wikipedia.org/wiki/Caesar_cypher This is what I was suggesting, which appears to be the same as the third method (Albam) of the Temurah cypher. Thanks, Ash http://www.ashleysheridan.co.uk
Re[6]: [PHP] preg_replace: avoiding double replacements
Hello Peter, Good point. And more than that, I make a decrypting script, also... so gibberish defenitely is an issue) -- 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: Peter Lind peter.e.l...@gmail.com To: a...@ashleysheridan.co.uk a...@ashleysheridan.co.uk Date: Tuesday, May 18, 2010, 3:00:56 PM Subject: [PHP] preg_replace: avoiding double replacements On 18 May 2010 13:43, Ashley Sheridan a...@ashleysheridan.co.uk wrote: On Tue, 2010-05-18 at 13:46 +0200, Peter Lind wrote: On 18 May 2010 13:32, Ashley Sheridan a...@ashleysheridan.co.uk wrote: On Tue, 2010-05-18 at 13:09 +0200, Peter Lind wrote: On 18 May 2010 12:35, Andre Polykanine an...@oire.org wrote: Hello Peter, Hm... I see I need to specify what I'm really doing. Actually, I need to change the letters in the text. It's a famous and ancient crypting method: you divide the alphabet making two parts, then you change the letters of one part with letters for other part (so A becomes N, B becomes O, etc., and vice versa). it works fine and slightly with strtr or str_replace... but only if the text is not in utf-8 and it doesn't contain any non-English letters such as Cyrillic what I need. What my regex does is the following: it sees an A, well it changes it to N; then it goes through the string and sees an N... what does it do? Surely, it changes it back to A! I hoped (in vain) that there exists a modifier preventing this behavior... but it seems that it's false( Thanks! Hmmm, what comes to mind is using your string as an array and translating one character after another, building your output string using a lookup table. Not entirely sure how that will play with utf8 characters, you'd have to try and see. I don't think you'll get any of PHPs string functions to do the work for you - they'll do the job in serial, not parallel. Regards Peter -- hype WWW: http://plphp.dk / http://plind.dk LinkedIn: http://www.linkedin.com/in/plind Flickr: http://www.flickr.com/photos/fake51 BeWelcome: Fake51 Couchsurfing: Fake51 /hype If you're wanting to use the Caesar cypher (for that's what it is) then why not just modify the entire string, character by character, to use a character code n characters ahead. For example, a capital A is ascii 65, you want to change it to an N to add 14 to that. Just keep n the same throughout and it's easy to convert back. Thanks, Ash http://www.ashleysheridan.co.uk You probably overlooked the part where the OP points out he's not using ascii but utf8. If it was just ascii, using str_rot13() would be the weapon of choice I'd say (note that adding 14 to every character of an ascii string will turn lots of it into gibberish - you have to wrap round when you reach a certain point). Regards Peter -- hype WWW: http://plphp.dk / http://plind.dk LinkedIn: http://www.linkedin.com/in/plind Flickr: http://www.flickr.com/photos/fake51 BeWelcome: Fake51 Couchsurfing: Fake51 /hype I gave the example as Ascii because I knew the code for A off the top of my head, I don't see a reason why it won't work for utf, the characters still have incremental codes. Also, is gibberish really an issue to worry about? The Caesar cypher is already rendering the string unreadable. You normally want output in the same range that you encode from (i.e. you're remapping within the alphabet, not within the entire range of printable characters) if you're doing a caesar/rot13. Regards Peter -- hype WWW: http://plphp.dk / http://plind.dk LinkedIn: http://www.linkedin.com/in/plind Flickr: http://www.flickr.com/photos/fake51 BeWelcome: Fake51 Couchsurfing: Fake51 /hype -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
