Last updated: Fri, 11 Apr 2008

preg_replace

(PHP 4, PHP 5)

preg_replace — Sucht und ersetzt einen regulären Ausdruck

Beschreibung

mixed preg_replace ( mixed $Suchmuster , mixed $Ersatz , mixed $Zeichenkette [, int $Limit [, int &$Anzahl ]] )

Durchsucht Zeichenkette nach Übereinstimmungen mit Suchmuster und ersetzt sie mit Ersatz .

Parameter-Liste

Suchmuster

Der Ausdruck, nach dem gesucht wird. Es kann entweder eine Zeichenkette oder ein Array mit Zeichenketten sein.

Mit dem Modifikator e wird der Parameter Ersatz nach den entsprechenden Ersetzungen der Referenzen von preg_replace() wie PHP-Code behandelt. Tipp: Stellen Sie sicher, dass Ersatz gültigen PHP-Code erzeugt, weil sich PHP sonst über einen Syntaxfehler (parse error) in der Zeile beschwert, die den Aufruf von preg_replace() enthält.

Ersatz

Die Zeichenkette oder das Array mit Zeichenketten zum Ersetzen. Falls dieser Parameter eine Zeichenkette ist und der Parameter Suchmuster ein Array, werden alle Suchmuster durch diese Zeichenkette ersetzt. Falls sowohl Suchmuster als auch Ersatz Arrays sind, wird jedes Suchmuster durch das Gegenstück aus Ersatz ersetzt. Wenn das Ersatz -Array weniger Elemente hat als das Suchmuster -Array, wird jedes überzählige Suchmuster durch die leere Zeichenkette ersetzt.

Ersatz darf Referenzen in der Form \\n oder (ab PHP 4.0.4) $n enthalten, wobei Letztere vorzuziehen ist. Jede dieser Referenzen wird mit dem Text ersetzt, der vom n-ten eingeklammerten Suchmuster erfasst wurde. n kann einen Wert von 0 bis 99 haben. \\0 oder $0 beziehen sich auf den Text, der auf das komplette Suchmuster passt. Um die Nummer des erfassenden Teil-Suchmusters zu erhalten, werden öffnende Klammern mit 1 beginnend von links nach rechts gezählt.

Wenn Sie mit einer Ersetzung arbeiten wollen, in der auf eine Rückreferenzierung direkt eine weitere Zahl folgt (d.h., direkt nach der Übereinstimmmung mit einem Suchmuster soll eine Zahl kommen), können Sie für Ihre Rückreferenzierung nicht die Schreibweise \\1 verwenden. So würde z.B. \\11 die Funktion preg_replace() verwirren, weil sie nicht weiß, ob Sie die Rückreferenzierung \\1 gefolgt von der Zahl 1 wollen oder nur die Rückreferenzierung \\11. In diesem Fall ist die Lösung, \${1}1 zu verwenden. Damit wird eine isolierte Rückreferenzierung $1 erzeugt und die 1 bleibt ein Buchstabensymbol.

Wenn Sie den Modifikator e verwenden, maskiert diese Funktion ein paar Zeichen (nämlich ', ", \ und NULL) in den Zeichenketten, mit denen die Rückreferenzierungen ersetzen werden. Das wird gemacht, um sicherzustellen, dass keine Syntaxfehler entstehen, wenn Rückreferenzierungen verwendet werden, die einfache oder doppelte Anführungszeichen enthalten (z.B. 'strlen(\'$1\')+strlen("$2")'). Vergewissern Sie sich, dass Sie die Zeichenketten-Syntax von PHP kennen, um genau zu wissen, wie die ausgewertete Zeichenkette aussieht.

Zeichenkette

Die Zeichenkette oder ein Array mit Zeichenketten zum Durchsuchen.

Falls Zeichenkette ein Array ist, wird das Suchen und Ersetzen auf jedes Element von Zeichenkette angewandt und der Rückgabewert ist ebenfalls ein Array.

Limit

Die maximal mögliche Anzahl von Ersetzungen für jedes Suchmuster in jeder Zeichenkette . Standardmäßiger Wert: -1 (kein Limit).

Anzahl

Falls angegeben, wird dieser Variable die Anzahl vorgenommener Ersetzungen zugewiesen.

Rückgabewerte

preg_replace() gibt ein Array zurück, falls Zeichenkette ein Array ist, andernfalls eine Zeichenkette.

Falls Übereinstimmungen gefunden wurden, wird die neue Zeichenkette zurückgegeben, andernfalls wird Zeichenkette unverändert zurückgegeben oder NULL, falls ein Fehler auftrat.

ChangeLog

Version	Beschreibung
5.1.0	Den Parameter `Anzahl` hinzugefügt
4.0.4	Die '$n'-Form für den Parameter `Ersatz` hinzugefügt
4.0.2	Den Parameter `Limit` hinzugefügt

Beispiele

Beispiel #1 Die Verwendung von Rückreferenzierungen mit darauf folgenden numerischen Literalen


<?php
$zeichenkette = '15. April 2003';
$suchmuster = '/(\d+)\. (\w+) (\d+)/i';
$ersetzung = '${2}1,$3';
echo preg_replace($suchmuster, $ersetzung, $zeichenkette);
?>

Das oben gezeigte Beispiel erzeugt folgende Ausgabe:

April1,2003

Beispiel #2 Die Verwendung von preg_replace() mit indizierten Arrays


<?php
$zeichenkette = 'Der schnelle braune Fuchs sprang über den faulen Hund.';

$suchmuster[0] = '/schnelle/';
$suchmuster[1] = '/braune/';
$suchmuster[2] = '/Fuchs/';

$ersetzungen[2] = 'Bär';
$ersetzungen[1] = 'schwarze';
$ersetzungen[0] = 'langsame';

echo preg_replace($suchmuster, $ersetzungen, $zeichenkette);
?>

Das oben gezeigte Beispiel erzeugt folgende Ausgabe:

Der Bär schwarze langsame sprang über den faulen Hund.

Wenn wir Suchmuster und Ersetzungen mit ksort() sortieren, sollten wir bekommen was wir wollten.


<?php
ksort($suchmuster);
ksort($ersetzungen);
echo preg_replace($suchmuster, $ersetzungen, $zeichenkette);
?>

Das oben gezeigte Beispiel erzeugt folgende Ausgabe:

Der langsame schwarze Bär sprang über den faulen Hund.

Beispiel #3 Ersetzen mehrerer Werte


<?php
$suchmuster = array ('/(19|20)(\d{2})-(\d{1,2})-(\d{1,2})/',
                     '/^\s*{(\w+)}\s*=/');
$ersetzen = array ('\4.\3.\1\2', '$\1 =');
echo preg_replace($suchmuster, $ersetzen, '{startDatum} = 1999-5-27');
?>

Das oben gezeigte Beispiel erzeugt folgende Ausgabe:

$startDatum = 27.5.1999

Beispiel #4 Die Verwendung des Modifikators 'e'


<?php
preg_replace("/(<\/?)(\w+)([^>]*>)/e",
             "'\\1'.strtoupper('\\2').'\\3'",
             $html_body);
?>

Das wandelt alle HTML-Tags des durchsuchten Textes in Großbuchstaben um.

Beispiel #5 Leerzeichen entfernen

Dieses Beispiel entfernt überschüssige Leerzeichen aus einer Zeichenkette.


<?php
$str = 'foo   o';
$str = preg_replace('/\s\s+/', ' ', $str);
// Das ist jetzt 'foo o'
echo $str;
?>

Beispiel #6 Die Verwendung des Parameters Anzahl


<?php
$anzahl = 0;

echo preg_replace(array('/\d/', '/\s/'), '*', 'xp 4 to', -1 , $anzahl);
echo $anzahl; //3
?>

Das oben gezeigte Beispiel erzeugt folgende Ausgabe:

xp***to
3

Anmerkungen

Hinweis: Bei Verwendung von Arrays für Suchmuster und Ersatz werden die Schlüssel in der Reihenfolge bearbeitet, in der sie im Array vorliegen. Das ist nicht notwendigerweise dieselbe, wie die numerische Reihenfolge der Indizes. Wenn Sie Indizes verwenden, um festzulegen welches Suchmuster durch welchen Ersatz ersetzt werden soll, sollten Sie vor dem Aufruf von preg_replace() ksort() auf jedes Array anwenden.

Siehe auch

preg_split

preg_replace_callback

Last updated: Fri, 11 Apr 2008

add a note User Contributed Notes
preg_replace

Michael W
17-Apr-2008 12:35


For filename tidying I prefer to only ALLOW certain characters rather than converting particular ones that we want to exclude. To this end I use ...



<?php

  $allowed = "/[^a-z0-9\\040\\.\\-\\_\\\\]/i";

  preg_replace($allowed,"",$str));

?>



Allows letters a-z, digits, space (\\040), hyphen (\\-), underscore (\\_) and backslash (\\\\), everything else is removed from the string.

Misha
25-Mar-2008 03:45


This is in response to iasmin at amazingdiscoveries dot org's URL text to link function. Hope this is helpful to someone.



I played with it a bit and came up with this version (there were one or two little errors in the regex I think, also -- it didn't allow various necessary characters).



I start with a URL in brackets (this works for my case):

[http://www.site.com/path/that/may/be_long.php?fun=1]



It returns a link of the URL after the "http://":

www.site.com/path/that/may/b...



-----------

    // Cuts off long URLs at $url_length, and appends "..."

    function reduceurl($url, $url_length) {

        $reduced_url = substr($url, 0, $url_length);

        if (strlen($url) > $url_length) $reduced_url .= '...';

        

        return $reduced_url;

    }



    // Makes URLs with brackets into links

    // The regex searches for "http://" or equivalent, then various character possibilities (I don't know if it might be possible to exploit this if more characters were allowed). The "e" after the regex allows the reduceurl() to be evaluated.



    function url2link($linktext) {

        $linktext = preg_replace("#\[(([a-zA-Z]+://)([a-zA-Z0-9?&%.;:/=+_-]*))\]#e", "'<a href=\"$1\" target=\"_blank\">' . reduceurl(\"$3\", 30) . '</a>'", $linktext);

                

        return $linktext;

    }

php-comments-REMOVE dot ME at dotancohen dot com
29-Feb-2008 09:02


Below is a function for converting Hebrew final characters to their

normal equivelants should they appear in the middle of a word.

The /b argument does not treat Hebrew letters as part of a word,

so I had to work around that limitation.



<?php



$text="עברית מבולגנת";



function hebrewNotWordEndSwitch ($from, $to, $text) {

   $text=

    preg_replace('/'.$from.'([א-ת])/u','$2'.$to.'$1',$text);

   return $text;

}



do {

   $text_before=$text;

   $text=hebrewNotWordEndSwitch("ך","כ",$text);

   $text=hebrewNotWordEndSwitch("ם","מ",$text);

   $text=hebrewNotWordEndSwitch("ן","נ",$text);

   $text=hebrewNotWordEndSwitch("ף","פ",$text);

   $text=hebrewNotWordEndSwitch("ץ","צ",$text);

}   while ( $text_before!=$text );



print $text; // עברית מסודרת!



?>



The do-while is necessary for multiple instances of letters, such

as "אנני" which would start off as "אןןי". Note that there's still the

problem of acronyms with gershiim but that's not a difficult one

to solve. The code is in use at http://gibberish.co.il which you can

use to translate wrongly-encoded Hebrew, transliterize, and some

other Hebrew-related functions.



To ensure that there will be no regular characters at the end of a

word, just convert all regular characters to their final forms, then

run this function. Enjoy!

Bryan Roach
15-Jan-2008 10:53


Jacob Fogg's clean_filename function is good, but there is a typo. Replace "\\x00-\\x40" with "\\x00-\\x20" or you will exclude too many characters.



Also keep in mind when checking file names to look for the special directory names ".." and ".". A user could potentially use those to reach an unexpected directory.

Jacob Fogg
14-Jan-2008 10:29


Here is my attempt at cleaning up a file name... it's similar to  what someone else has done however a little cleaner with the addition of the | in the reserved characters... also I clean any characters from x00 to x40 (all non display characters and space) as well as everything greater than 7f and greater (removes the Del character and other non English characters), replacing them with an '_'.



function clean_filename($filename){//function to clean a filename string so it is a valid filename

$reserved = preg_quote('\/:*?"<>|', '/');//characters that are  illegal on any of the 3 major OS's

//replaces all characters up through space and all past ~ along with the above reserved characters

return preg_replace("/([\\x00-\\x40\\x7f-\\xff{$reserved}])/e", "_", $filename);

}

admin[a-t]saltwaterc[d0t]net
11-Dec-2007 05:17


Actually I made a mistake in my previous post. In order to make the function more effective ... I broke it. The original which works (really) looks like this:



<?php

function repl_amp($text)

    {

    $text=preg_replace("/&(?!amp;)/i", "&amp;", $text);

    $text=preg_replace("/&amp;#(\d+);/i", "&#$1;", $text); // For numeric entities

    $text=preg_replace("/&amp;(\w+);/i", "&$1;", $text); // For literal entities

    return $text;

    }

?>



The RegEx Tester says that the first expression is OK, but when testing with various entities, some of them came out broken. I'd tried to use only 2 preg_replace(); calls instead of three by using the alternative branch from the pattern syntax - which didn't came out well. Sorry for the previous error, and I still hope that someone can find a better alternative.

ulf dot reimers at tesa dot com
07-Dec-2007 07:28


Hi,



as I wasn't able to find another way to do this, I wrote a function converting any UTF-8 string into a correct NTFS filename (see http://en.wikipedia.org/wiki/Filename).



<?php

function strToNTFSFilename($string)

{

  $reserved = preg_quote('\/:*?"<>', '/');

  return preg_replace("/([\\x00-\\x1f{$forbidden}])/e", "_", $string);

}

?>



It converts all control characters and filename characters which are reserved by Windows ('\/:*?"<>') into an underscore.

This way you can safely create an NTFS filename out of any UTF-8 string.

Anonymous
30-Nov-2007 09:26


This code is much easier than preg_replaces current implementation, I stole some of this from someone else here, but to make it more explicit:



$relation['/pattern/'] = "replacement";



$text_out = preg_replace(array_keys($relation), array_values($relation), $text_in);



Fast, efficient, no guess work..

Santosh Patnaik
23-Oct-2007 08:35


@giel dot berkers



Use the 'PCRE_DOTALL' ('s') option so that the '.' covers newline characters:



$code = preg_replace('/\/\*.*\*\//ms', '', $code);

mike dot hayward at mikeyskona dot co dot uk
18-Oct-2007 05:49


Hi.

Not sure if this will be a great help to anyone out there, but thought i'd post just in case.

I was having an Issue with a project that relied on $_SERVER['REQUEST_URI']. Obviously this wasn't working on IIS.

(i am using mod_rewrite in apache to call up pages from a database and IIS doesn't set REQUEST_URI). So i knocked up this simple little preg_replace to use the query string set by IIS when redirecting to a PHP error page.



<?

//My little IIS hack :)

if(!isset($_SERVER['REQUEST_URI'])){ 

$_SERVER['REQUEST_URI'] = preg_replace( '/404;([a-zA-Z]+:\/\/)(.*?)\//i', "/" , $_SERVER['QUERY_STRING'] );

}

?>



Hope this helps someone else out there trying to do the same thing :)



If anyone finds a better way, please let met know, I'm still learning ;)

matt
28-Sep-2007 05:52


at below post:

<?php

 $template = "Price: #price#";

 $price    = '&#36;5';

 print "Price: $price\n";

 $res    = preg_replace("/#price#/", $price, $template);

 print "From template: -> $res\n";



 ?>

jefkin at gmail dot com
20-Sep-2007 03:52


@ Santosh Patnaik



The perl regular expression engine will handle this expression better and much faster by using the word boundry escape code \b.  Though it may not be obvious except to long time perl geeks such as I :)



so:



// Expect and get 'pa pa pa pa'

echo preg_replace('`\bma\b`', 'pa', 'ma ma ma ma');



Jeff

Santosh Patnaik
14-Sep-2007 08:11


Once a match is identified, the regular expression engine appears to set aside the matching segment of the target string. A second segment that you expect to match may therefore end up not getting matched:



// Expect 'pa pa pa pa' but get 'pa ma pa ma'

echo preg_replace('`(^|\s)ma(\s|$)`', '$1pa$2', 'ma ma ma ma');



Here the issue can be solved by using a 'lookahead':



// Expect and get 'pa pa pa pa'

echo preg_replace('`(^|\s)ma(?=\s|$)`', '$1pa', 'ma ma ma ma');

iasmin at amazingdiscoveries dot org
13-Sep-2007 04:37


I thought that someone could use this hyperlink function. 

preg_replace is about 6 times faster than ereg_replace. I took the original example from the ereg_replace function page and modified so that it works perfect. I gave a comment of what it matches.

One thing is that I added a space at the beginning so that only links that don't have <a href="" around them or anything else touching will be replaced. 



<i>NOTE! I had to break the long lines otherwise I couldn't have posted this. So take the new line out and it will work</i>

<?php

function hyperlink(&$text)

    {

       // match protocol://address/path/file.extension?some=variable&another=asf%

       $text = preg_replace("/\s(([a-zA-Z]+:\/\/)([a-z][a-z0-9_\..-]*

[a-z]{2,6})([a-zA-Z0-9\/*-?&%]*))\s/i", " <a href=\"$1\">$3</a> ", $text);

    

       // match www.something.domain/path/file.extension?some=variable&another=asf%

       $text = preg_replace("/\s(www\.([a-z][a-z0-9_\..-]*

[a-z]{2,6})([a-zA-Z0-9\/*-?&%]*))\s/i", " <a href=\"http://$1\">$2</a> ", $text);

       

       return $text;

    }

?>



Play around with it and see how it works. 

Courtesy of AmazingDiscoveries.org 

God bless, Iasmin Balaj

sternkinder at gmail dot com
24-Aug-2007 12:10


From what I can see, the problem is, that if you go straight and substitute all 'A's wit 'T's you can't tell for sure which 'T's to substitute with 'A's afterwards. This can be for instance solved by simply replacing all 'A's by another character (for instance '_' or whatever you like), then replacing all 'T's by 'A's, and then replacing all '_'s (or whatever character you chose) by 'A's:



$dna = "AGTCTGCCCTAG";

echo str_replace(array("A","G","C","T","_","-"), array("_","-","G","A","T","C"), $dna); //output will be TCAGACGGGATC



Although I don't know how transliteration in perl works (though I remember that is kind of similar to the UNIX command "tr") I would suggest following function for "switching" single chars:



function switch_chars($subject,$switch_table,$unused_char="_") {

    foreach ( $switch_table as $_1 => $_2 ) {

        $subject = str_replace($_1,$unused_char,$subject);

        $subject = str_replace($_2,$_1,$subject);

        $subject = str_replace($unused_char,$_2,$subject);

    }

    return $subject;

}



echo switch_chars("AGTCTGCCCTAG", array("A"=>"T","G"=>"C")); //output will be TCAGACGGGATC

rob at ubrio dot us
21-Aug-2007 10:48


Also worth noting is that you can use array_keys()/array_values() with preg_replace like:



$subs = array(

  '/\[b\](.+)\[\/b\]/Ui' => '<strong>$1</strong>',

  '/_(.+)_/Ui' => '<em>$1</em>'

  ...

  ...

);



$raw_text = '[b]this is bold[/b] and this is _italic!_';



$bb_text = preg_replace(array_keys($subs), array_values($subs), $raw_text);

lehongviet at gmail dot com
25-Jul-2007 10:15


I got problem echoing text that contains double-quotes into a text field. As it confuses value option. I use this function below to match and replace each pair of them by smart quotes. The last one will be replaced by a hyphen(-).



It works for me.



function smart_quotes($text) {

 $pattern = '/"((.)*?)"/i';

 $text = preg_replace($pattern,"&#147;\\1&#148;",stripslashes($text));

$text = str_replace("\"","-",$text);

$text = addslashes($text);

return $text;

}

131 dot php at cloudyks dot org
17-Jul-2007 01:37


Based on previous comment, i suggest 

( this function already exist in php 6 )



function unicode_decode($str){

    return preg_replace(

        '#\\\u([0-9a-f]{4})#e',

        "unicode_value('\\1')",

        $str);

}

function unicode_value($code) {

    $value=hexdec($code);

    if($value<0x0080)

        return chr($value);

    elseif($value<0x0800)

        return chr((($value&0x07c0)>>6)|0xc0)

            .chr(($value&0x3f)|0x80);

    else

        return chr((($value&0xf000)>>12)|0xe0)

        .chr((($value&0x0fc0)>>6)|0x80)

        .chr(($value&0x3f)|0x80);

}

ismith at nojunk dot motorola dot com
21-Mar-2007 06:47


Be aware that when using the "/u" modifier, if your input text contains any bad UTF-8 code sequences, then preg_replace will return an empty string, regardless of whether there were any matches.



This is due to the PCRE library returning an error code if the string contains bad UTF-8.

mrozenoer at overstream dot net
07-Mar-2007 05:30


I could not find a function to unescape javascript unicode escapes anywhere (e.g., "\u003c"=>"<"). 





<?php


function js_uni_decode($s) {


    return preg_replace('/\\\u([0-9a-f]{4})/ie', "chr(hexdec('\\1'))",  $s);


}


echo js_uni_decode("\u003c");


?>

dani dot church at gmail dot youshouldknowthisone
07-Feb-2007 08:09


Note that it is in most cases much more efficient to use preg_replace_callback(), with a named function or an anonymous function created with create_function(), instead of the /e modifier.  When preg_replace() is called with the /e modifier, the interpreter must parse the replacement string into PHP code once for every replacement made, while preg_replace_callback() uses a function that only needs to be parsed once.

Alexey Lebedev
07-Sep-2006 11:21


Wasted several hours because of this:



$str='It&#039;s a string with HTML entities';

preg_replace('~&#(\d+);~e', 'code2utf($1)', $str);



This code must convert numeric html entities to utf8. And it does with a little exception. It treats wrong codes starting with &#0



The reason is that code2utf will be called with leading zero, exactly what the pattern matches - code2utf(039).

And it does matter! PHP treats 039 as octal number.

Try print(011);



Solution:

preg_replace('~&#0*(\d+);~e', 'code2utf($1)', $str);

robvdl at gmail dot com
21-Apr-2006 02:15


For those of you that have ever had the problem where clients paste text from msword into a CMS, where word has placed all those fancy quotes throughout the text, breaking the XHTML validator... I have created a nice regular expression, that replaces ALL high UTF-8 characters with HTML entities, such as &#8217;.



Note that most user examples on php.net I have read, only replace selected characters, such as single and double quotes. This replaces all high characters, including greek characters, arabian characters, smilies, whatever.



It took me ages to get it just downto two regular expressions, but it handles all high level characters properly.



$text = preg_replace('/([\xc0-\xdf].)/se', "'&#' . ((ord(substr('$1', 0, 1)) - 192) * 64 + (ord(substr('$1', 1, 1)) - 128)) . ';'", $text);

$text = preg_replace('/([\xe0-\xef]..)/se', "'&#' . ((ord(substr('$1', 0, 1)) - 224) * 4096 + (ord(substr('$1', 1, 1)) - 128) * 64 + (ord(substr('$1', 2, 1)) - 128)) . ';'", $text);

gabe at mudbuginfo dot com
18-Oct-2004 10:39


It is useful to note that the 'limit' parameter, when used with 'pattern' and 'replace' which are arrays, applies to each individual pattern in the patterns array, and not the entire array.

<?php



$pattern = array('/one/', '/two/');

$replace = array('uno', 'dos');

$subject = "test one, one two, one two three";



echo preg_replace($pattern, $replace, $subject, 1);

?>



If limit were applied to the whole array (which it isn't), it would return:

test uno, one two, one two three



However, in reality this will actually return:

test uno, one dos, one two three

steven -a-t- acko dot net
08-Feb-2004 06:45


People using the /e modifier with preg_replace should be aware of the following weird behaviour. It is not a bug per se, but can cause bugs if you don't know it's there.



The example in the docs for /e suffers from this mistake in fact.



With /e, the replacement string is a PHP expression. So when you use a backreference in the replacement expression, you need to put the backreference inside quotes, or otherwise it would be interpreted as PHP code. Like the example from the manual for preg_replace:



preg_replace("/(<\/?)(\w+)([^>]*>)/e",

             "'\\1'.strtoupper('\\2').'\\3'",

             $html_body);



To make this easier, the data in a backreference with /e is run through addslashes() before being inserted in your replacement expression. So if you have the string



 He said: "You're here"



It would become:



 He said: \"You\'re here\"



...and be inserted into the expression.

However, if you put this inside a set of single quotes, PHP will not strip away all the slashes correctly! Try this:



 print ' He said: \"You\'re here\" ';

 Output: He said: \"You're here\"



This is because the sequence \" inside single quotes is not recognized as anything special, and it is output literally.



Using double-quotes to surround the string/backreference will not help either, because inside double-quotes, the sequence \' is not recognized and also output literally. And in fact, if you have any dollar signs in your data, they would be interpreted as PHP variables. So double-quotes are not an option.



The 'solution' is to manually fix it in your expression. It is easiest to use a separate processing function, and do the replacing there (i.e. use "my_processing_function('\\1')" or something similar as replacement expression, and do the fixing in that function).



If you surrounded your backreference by single-quotes, the double-quotes are corrupt:

$text = str_replace('\"', '"', $text);



People using preg_replace with /e should at least be aware of this.



I'm not sure how it would be best fixed in preg_replace. Because double-quotes are a really bad idea anyway (due to the variable expansion), I would suggest that preg_replace's auto-escaping is modified to suit the placement of backreferences inside single-quotes (which seemed to be the intention from the start, but was incorrectly applied).

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preg_split

preg_replace_callback

Last updated: Fri, 11 Apr 2008