$newstr = preg_replace('/[^a-zA-Z0-9\']/', '_', "There wouldn't be any");
$newstr = str_replace("'", '', $newstr);

I put them on two separate lines to make the code a little more clear.

Note: If you're looking for Unicode support, see Filip's answer below. It will match all characters that register as letters in addition to A-z.

Answer from Chris Bornhoft on Stack Overflow
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Stack Overflow
stackoverflow.com › questions › 8483546 › php-preg-replace-special-characters
PHP preg_replace special characters - Stack Overflow
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44
$newstr = preg_replace('/[^a-zA-Z0-9\']/', '_', "There wouldn't be any");
$newstr = str_replace("'", '', $newstr);

I put them on two separate lines to make the code a little more clear.

Note: If you're looking for Unicode support, see Filip's answer below. It will match all characters that register as letters in addition to A-z.

2 of 3
43

If you by writing "non letters and numbers" exclude more than [A-Za-z0-9] (ie. considering letters like åäö to be letters to) and want to be able to accurately handle UTF-8 strings \p{L} and \p{N} will be of aid.

  1. \p{N} will match any "Number"
  2. \p{L} will match any "Letter Character", which includes
    • Lower case letter
    • Modifier letter
    • Other letter
    • Title case letter
    • Upper case letter

Documentation PHP: Unicode Character Properties

$data = "Thäre!wouldn't%bé#äny";

$new_data = str_replace  ("'", "", $data);
$new_data = preg_replace ('/[^\p{L}\p{N}]/u', '_', $new_data);

var_dump (
  $new_data
);

output

string(23) "Thäre_wouldnt_bé_äny"
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PHP
php.net › manual › en › function.preg-replace.php
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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! ... 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: <?php $dna = "AGTCTGCCCTAG"; echo str_repl
Discussions
preg_replace remove special characters - PHP Coding Help - PHP Freaks
Forgot your password · By jasonc310771 December 15, 2022 in PHP Coding Help More on forums.phpfreaks.com
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How can I preg_replace with special characters, numbers and everything? - PHP - SitePoint Forums | Web Development & Design Community
How can I preg_replace with special characters, numbers and everything · BTW, if you want to use regular expressions, only the pattern is a regex; the replacement is a string where you can access captured matches like “$1” (say) · This topic was automatically closed 91 days after the ... More on sitepoint.com
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August 8, 2016
preg_replace to allow special characters
Hello I am using following code to allow characters like A to Z and numeric values like 0 to 9. $result = preg_replace('/[^a-zA-Z0-9_]/', '',... More on forums.digitalpoint.com
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php - Preg_replace special characters & - Stack Overflow
Good afternoon, I have an error in my preg_replace. I would like to replace && with only one &, and ?& with ?. My code looks like this: $reg = preg_replace("#\&\&#is", "... More on stackoverflow.com
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preg_replace remove special characters - PHP Coding Help - PHP Freaks
December 15, 2022 - $string = "t*e*s*t"; $pattern = "/[^A-Za-zÀ-ÿ0-9\-\_\(\)\[\]\{\} ]/"; // keep all language letters, numbers, all types of brackets, spaces, hyphen, dash fullstop $cleanStr = preg_replace($pattern, '', $string); echo("{" . $cleanStr . "}"); I do not understand why this is not working, apart from t...
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CodexWorld
codexworld.com › home › how to guides › how to remove special characters from string in php
How to Remove Special Characters from String in PHP - CodexWorld
September 13, 2018 - The following code removes the special characters from string with regular expression pattern (Regex) in PHP. $string = "Wel%come *to( codex<world, the |world o^f pro?gramm&ing."; // Remove special characters $cleanStr = preg_replace('/[^A-Za-z0-9]/', '', $string);
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How can I preg_replace with special characters, numbers and everything? - PHP - SitePoint Forums | Web Development & Design Community
August 8, 2016 - $pattern = ‘/^([0-9]{3})001([0-9]{0,})$/’; $replacement = ‘/^([0-9]{3})001([0-9]{0,})$/’; $subject = ‘CLP520001103480891775486.2**1202014282509832Z0X00221~ NM1QC1BALLWANDAMIR59915931~ NM1IL1BALLEDWARDMIR59915931~ NM…
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gist.github.com › qutek › 0a542a24815764464106
[php] Replace special character using preg replace · GitHub
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forums.digitalpoint.com › threads › preg_replace-to-allow-special-characters.1530917
preg_replace to allow special characters
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Stack Overflow
stackoverflow.com › questions › 33595191 › preg-replace-special-characters
php - Preg_replace special characters & - Stack Overflow
Top answer
1 of 2
4

You do not need to escape & only the ?

$reg = preg_replace("#&&#", "&", $reg);

$reg = preg_replace("#\?&#", "?", $reg);
2 of 2
1

You can simplify the two regexs into one.

echo preg_replace("#([?&])\s*&#", "$1", ' ? &lang=en');

Output:

 ?lang=en

Your modifiers didn't make sense since you aren't using alpha characters or the ..

Also & isn't a special regex character, just ?. If in a character class ([]) neither will need to be replaced.

Regex101 Demo: https://regex101.com/r/iS4mQ0/1

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Delft Stack
delftstack.com › home › howto › php › remove special characters from string php
How to Remove Special Character in PHP | Delft Stack
February 2, 2024 - On the other hand, if both $pattern and $replaceWith parameters are arrays, then it does the same as in the above condition but replace the specific indexed string of $pattern with its responding counter index of $replaceWith. $string: This is the desirable string you want to filter with a special character. See the example below. <?php function RemoveSpecialChar($str) { $res = preg_replace('/[0-9\@\.\;\" "]+/', '', $str); return $res; } $str = "My name is hello and email hello.world598@gmail.com;"; $str1 = RemoveSpecialChar($str); echo "My UpdatedString: ", $str1; ?>
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Stack Overflow
stackoverflow.com › questions › 28161898 › preg-replace-with-lots-of-special-characters
php - preg_replace with lots of special characters - Stack Overflow
Top answer
1 of 3
1

I think you want something like this pattern?

(\?dead(=[^&]*|))*

PHP Code:

echo preg_replace('/(\?dead(=[^&]*|))*/','',$sourcestring);

This will produce this output of your given urls:

http://www.url.com/&wow=test
http://www.url.com/&wow=test
http://www.url.com/?hello
2 of 3
0

You can use \Q and \E (as in QuotE) when dealing with lots of special characters.

The text between these delimiters will be treated literally.

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Stack Overflow
stackoverflow.com › questions › 15749374 › php-preg-replace-with-special-characters
regex - PHP preg_replace with special characters - Stack Overflow
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1 of 3
1

That regex just seems to have a lot of unnecessary problems. As Otala said, the hypen isn't escaped, the pipe isn't escaped and it's not looking for periods. Also it had two checks for hyphens.

You should simplify it by simply looking for all non-pipe characters up to the pipe:

preg_replace("/([^|\r\n]+)\|/", '<h3 id="${1}">${1}</h3>', $content);
2 of 3
0

Could simplify your regex a bit: preg_replace("/([^|\n\r]+\|\n)/", '${1}', $content);

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CodeSpeedy
codespeedy.com › home › remove special characters from string in php
Remove special characters from string in PHP - CodeSpeedy
September 15, 2022 - <!DOCTYPE html> <html> <body> <?php $str = "code@5 speedy!3*^&% tutorial#$"; $str = str_replace(' ','-',$str); $str = preg_replace('/[^A-Za-z\-]/', '', $str); // Printing the result echo $str; ?> </body> </html>
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November 28, 2022 - If you need to remove only specific special characters, it’s better to use the str_replace() function. When you need to remove all special characters, use the preg_replace() function.
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March 31, 2026 - <?php // Define the input string $string = 'abcde$ddfd @abcd )der]'; // Print the old string echo 'Old string : '.$string.''; // Remove all characters except letters, numbers, and spaces using regular expression $newstr = preg_replace("/[^A-Za-z0-9 ]/", '', $string); // Print the new string after removing unwanted characters echo 'New string : '.$newstr."\n"; ?>
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Stack Overflow
stackoverflow.com › questions › 3436746 › help-with-preg-replace-and-special-chars
php - Help with preg_replace and special chars - Stack Overflow
Top answer
1 of 2
2

You need to add /u pattern modifier to your pattern to turn on UTF-8 support in PCRE. This is assuming everything is in UTF-8 already.

http://www.php.net/manual/en/reference.pcre.pattern.modifiers.php

2 of 2
1
$str = '$#$<<>-//La souris a été mangée par le chat ';
$str = preg_replace('/[^a-zA-Z0-9éàêïòé\,\.\']/u',' ',trim($str));

$str = '$#$<<>-//La souris a été mangée par le chat ';
$str = preg_replace('/[^\p{L}\,\.\']/u',' ',trim($str));

Both the snippets worked for me, on PHP 5.3. The second regular expression is less restricted, and accepts all Unicode letters.

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GitHub
gist.github.com › rahuldadhich › 34ad681ebe3a7bd57da416cceba89d31
PHP - Remove all special characters including white space, multiple space · GitHub
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Stack Overflow
stackoverflow.com › questions › 10482841 › preg-replace-special-chars
php - preg_replace special chars - Stack Overflow
Top answer
1 of 1
1

Try this :

 <a href="<?php echo $row->id;?>/
 <?=trim(preg_replace('#[^\w\-]+#','_', strtolower($row->showTitle())), '_')?>.html">

It will remove any trailing underscore.