Last updated: Fri, 06 Nov 2009

preg_quote

(PHP 4, PHP 5)

preg_quote — Adiciona escape em caracteres da expressão regular

Descrição

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

preg_quote() pega str e coloca uma barra invertida antes de cada caractere que é parte da sintaxe da expressão regular. Isto é útil se você tem uma string em run-time que você precisa combinar em algum texto e a string pode conter caracteres especiais de regex.

Os caracteres especiais da expressão regular são . \ + * ? [ ^ ] $ ( ) { } = ! < > | :

Parâmetros

str: A string de entrada.
delimiter: Se o opcional delimiter é especificado, ele também terá escape antecedendo. Isto é útil para adicionar escape em delimitadores que é requerido pelas funções PCRE. A / é o delimitador mais comumente usado.

Valor Retornado

Retorna a string modificada.

Exemplos

Exemplo #1 Exemplo da preg_quote()


<?php
$keywords = '$40 for a g3/400';
$keywords = preg_quote($keywords, '/');
echo $keywords; // returns \$40 for a g3\/400
?>

Exemplo #2 Deixando em itálico uma palavra de um texto


<?php
// In this example, preg_quote($word) is used to keep the
// asterisks from having special meaning to the regular
// expression.

$textbody = "This book is *very* difficult to find.";
$word = "*very*";
$textbody = preg_replace ("/" . preg_quote($word) . "/",
                          "<i>" . $word . "</i>",
                          $textbody);
?>

Notas

Nota: Esta função é compatível com dados binários

preg_replace_callback

preg_match

Last updated: Fri, 06 Nov 2009

add a note User Contributed Notes
preg_quote

zooly
21-Jul-2009 06:07


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

alexc223 at NOSPAM dot googlemail dot com
15-Jun-2009 05:41


Not sure why this note got deleted, but hey lets try again:



As of PHP 5.3, bug #47229 has been fixed and preg_quote *will* escape a hyphen (-). This may effect your code so ensure this is one thing you check when moving to 5.3.

frostschutz
20-Mar-2009 08:01


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 [].

krishoog at gmail dot com
13-Oct-2008 12:51


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.

bizzigul at hotmail dot fr
30-Jul-2008 02:10


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...

Anonymous
26-Dec-2007 09:13


Wondering why your preg_replace fails, even if you have used preg_quote?



Try adding the delimiter / - preg_quote($string, '/');

add a note

preg_replace_callback

preg_match

Last updated: Fri, 06 Nov 2009