PHP preg_replace problem

Question

This is a follow-up question to the one I posted here (thanks to mario)

Ok, so I have a preg_replace statement to replace a url string with sometext, insert a value from a query string (using $_GET["size"]) and insert a value from a associative array (using $fruitArray["$1"] back reference.)

Input url string would be:

http://mysite.com/script.php?fruit=apple

Output string should be:

http://mysite.com/small/sometext/green/

The PHP I have is as follows:

$result = preg_replace('|http://www.mysite.com/script.php\?fruit=([a-zA-Z0-9_-]*)|e', ' "http://www.mysite.com/" .$_GET["size"]. "/sometext/" .$fruitArray["$1"]. "/"', $result);

This codes outputs the following string:

 http://mysite.com/small/sometext//

The code seems to skip the value in $fruitArray["$1"].

What am I missing?

Thanks!

When asking such a question, you should entirely remove the $_GET and $fruitArray and use constants instead, to localize the problem to the preg_replace only. Maybe your variables are empty, we can't know it for sure — Riccardo Galli
– Riccardo Galli, Commented May 12, 2011 at 17:23
@Riccardo Galli You are quite correct there, lesson learnt - must stop writing php on the back of a fag packet and move to a PHP IDE - do you have any recommendations? I'm such a noob :/ Cheers. — Matt
– Matt, Commented May 12, 2011 at 19:23
Managed to solve this by re-writing some of the preceding code; I had other preg_replace calls interfering with the url string :/ Perhaps my code above was semi-OK after all :-) This project started small but now its hundreds and hundreds of lines of code - Apologies to all - I do appreciate the answers though, cheers! — Matt
– Matt, Commented May 12, 2011 at 19:28

Rudi Visser · Accepted Answer · 2011-05-12 17:47:31Z

1

Well, weird thing.

Your code work's perfectly fine for me (see below code that I used for testing locally).

I did however fix 2 things with your regex:

Don't use | as a delimiter, it has meaning in regex.
Your regular expression is only giving the illusion that it works as you're not escaping the .s. It would actually match http://www#mysite%com/script*php?fruit=apple too.

Test script:

$fruitArray = array('apple' => 'green');
$_GET = array('size' => 'small');
$result = 'http://www.mysite.com/script.php?fruit=apple';
$result = preg_replace('@http://www\.mysite\.com/script\.php\?fruit=([a-zA-Z0-9_-]*)@e', ' "http://www.mysite.com/" .$_GET["size"]. "/sometext/" .$fruitArray["$1"]. "/"', $result);
echo $result;

Output:

Rudis-Mac-Pro:~ rudi$ php tmp.php
http://www.mysite.com/small/sometext/green/

The only thing this leads me to think is that $fruitArray is not setup correctly for you.

By the way, I think this may be more appropriate, as it will give you more flexibility in the future, better syntax highlighting and make more sense than using the e modifier for the evil() function to be internally called by PHP ;-) It's also a lot cleaner to read, IMO.

$result = preg_replace_callback('@http://www\.mysite\.com/script\.php\?fruit=([a-zA-Z0-9_-]*)@', function($matches) {
        global $fruitArray;
        return 'http://www.mysite.com/' . $_GET['size'] . '/sometext/' . $fruitArray[$matches[1]] . '/';
}, $result);

edited May 12, 2011 at 17:47

answered May 12, 2011 at 17:35

Rudi Visser

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2 Comments

Matt Over a year ago

Thank you for your detailed answer and for pointing out better ways of doing this; it's appreciated. I'm off to have a go at preg_replace_callback, something new for me, cheers :)

Rudi Visser Over a year ago

No problem! Glad I could help, also relieved to hear it wasn't this code you posted as it was confusing me that it would work for me and not you ;-)

Felipe Buccioni · Accepted Answer · 2011-05-12 17:41:20Z

1

i write it again, i don't understand good where is the error, the evaluation of preg results is very weird in php

preg_replace(
    '|http\://([\w\.-]+?)/script\.php\?fruit=([\w_-]+)|e'
    , '"http://www.$1/".$_GET["size"]."/sometext/".$fruitArray["$2"]."/";'
    , $result
);

answered May 12, 2011 at 17:41

Felipe Buccioni

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2 Comments

Matt Over a year ago

thanks for your effort, I managed to resolve this now though. regex is so powerful yet so hard to master :/ Cheers!

Felipe Buccioni Over a year ago

@Matt regexp are powerful as you say, but sometimes is hard to be human readable even if you write it, and is a good practice write it again. Regexps are just practice... keep in that way a regexp question is always a nifty question.

mellamokb · Accepted Answer · 2011-05-12 17:13:51Z

0

It looks like you have forgotten to escape the ?. It should be /script.php\?, with a \? to escape properly, as in the linked answer you provided.

answered May 12, 2011 at 17:13

mellamokb

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1 Comment

Matt Over a year ago

whoops, I just forgot to do that in the example posted here; the actual code is escaped properly. Code updated, thanks for pointing it out - problem remains.

koen · Accepted Answer · 2011-05-12 17:21:02Z

0

$fruitArray["\$1"] instead of $fruitArray["$1"]

answered May 12, 2011 at 17:21

koen

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