PHP 5.4.33 Released

preg_quote

(PHP 4, PHP 5)

preg_quoteProtection des caractères spéciaux des expressions rationnelles

Description

string preg_quote ( string $str [, string $delimiter = NULL ] )

preg_quote() ajoute un antislash devant tous les caractères de la chaîne str. Cela est très utile si vous avez une chaîne qui va servir de masque, mais qui est générée durant l'exécution.

Les caractères spéciaux qui seront protégés sont les suivants : . \ + * ? [ ^ ] $ ( ) { } = ! < > | : -

Liste de paramètres

str

La chaîne d'entrée.

delimiter

Si l'argument optionnel delimiter est fourni, il sera aussi échappé. Ceci est pratique pour échapper le délimiteur requis par les fonctions PCRE. Le slash / est le délimiteur le plus répandu.

Valeurs de retour

Retourne la chaîne protégée.

Historique

Version Description
5.3.0 Le caractère - est maintenant protégé.

Exemples

Exemple #1 Exemple avec preg_quote()

<?php
$keywords 
'$40 pour un g3/400';
$keywords preg_quote($keywords'/');
echo 
$keywords// retourne \$40 pour un g3\/400
?>

Exemple #2 Mise en italique d'un mot dans un texte

<?php
// Dans cet exemple, preg_quote($word) sert à éviter que les astérisques
// prennent une valeur particulière dans l'expression rationnelle.

$textbody "Ce livre est *très* difficile à trouver.";
$word "*très*";
$textbody preg_replace ("/" preg_quote($word) . "/",
                          
"<i>" $word "</i>",
                          
$textbody);
?>

Notes

Note: Cette fonction gère les chaînes binaires.

Voir aussi

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User Contributed Notes 6 notes

up
11
Anonymous
6 years ago
Wondering why your preg_replace fails, even if you have used preg_quote?

Try adding the delimiter / - preg_quote($string, '/');
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7
krishoog at gmail dot com
5 years ago
To bizzigul at hotmail dot fr:
It's not a good practice to make somthing work *almost* all of the time. If the input contains a '`' you will still get an error. I recommend using the default delimiter ('/') and also feed this to preg_quote as second argument.
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3
zooly
5 years ago
To escape characters with special meaning, like: .-[]() and so on, use \Q and \E.

For example:

<?php echo ( preg_match('/^'.( $myvar = 'te.t' ).'$/i', 'test') ? 'match' : 'nomatch' ); ?>

Will result in: match

But:

<?php echo ( preg_match('/^\Q'.( $myvar = 'te.t' ).'\E$/i', 'test') ? 'match' : 'nomatch' ); ?>

Will result in: nomatch
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2
frostschutz
5 years ago
I wanted to escape a string of characters so I could match them in [], i.e. [.,-!"§$%\\\[\]\^].

Unfortunately preg_quote does not escape the - character which has a special meaning in [], i.e. [a-z].

So I used this hack: make - the delimiter of the expression, i.e.

preg_quote(userinput, "-")
preg_replace("-[$userinput]-u", "", $str)

Apparently using a special char as a delimiter of a regular expression disables this character, i.e. even if it's escaped it's not understood as special character for the expression anymore.

so the pattern "-[a\\-z]-u" matches the characters a, - and z, and not abc...xyz.

It would be nice if preg_quote also escaped characters that have special meanings even if they have this meaning only under certain conditions, such as inside [].
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1
ian at broster dot co dot uk
15 days ago
Note that slash '/' is not one of the special characters, the italic writing of the list above makes pipe '|' look like '/'.
up
1
bizzigul at hotmail dot fr
6 years ago
To prevent any problems, try to always use a delimiter that will *almost* not be used inside the regex, such as ` (back quote)

for example: instead of
<?php preg_match('/foo\/bar\//',$somevar); ?>

use

<?php preg_match('`foo/bar/`',$somevar); ?>

it's that simple! like this, you won't have to bother with delimiters anymore...
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