preg_quote

(PHP 4, PHP 5)

preg_quoteQuote regular expression characters

Description

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

preg_quote() takes str and puts a backslash in front of every character that is part of the regular expression syntax. This is useful if you have a run-time string that you need to match in some text and the string may contain special regex characters.

The special regular expression characters are: . \ + * ? [ ^ ] $ ( ) { } = ! < > | : -

Parameters

str

The input string.

delimiter

If the optional delimiter is specified, it will also be escaped. This is useful for escaping the delimiter that is required by the PCRE functions. The / is the most commonly used delimiter.

Return Values

Returns the quoted (escaped) string.

Changelog

Version Description
5.3.0 The - character is now quoted

Examples

Example #1 preg_quote() example

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

Example #2 Italicizing a word within some text

<?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);
?>

Notes

Note: This function is binary-safe.

See Also

Коментарии

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

Try adding the delimiter / - preg_quote($string, '/');
2007-12-26 17:13:11
http://php5.kiev.ua/manual/ru/function.preg-quote.html
Автор:
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
2009-07-21 04:07:11
http://php5.kiev.ua/manual/ru/function.preg-quote.html
List of specials is incomplete:

--- sample code ---

$specials = '.\+*?[^]$(){}=!<>|:-';

for ($i = 0; $i <= 255; $i++) {

    if (chr($i) !== preg_quote(chr($i))) {

        printf("Character 0x%02x quoted%s\n",
               $i,
               (strpos($specials, chr($i)) === FALSE) ? ' (+)' : '');
    } /* if */
} /* for */

--- sample code ---

--- output ---

Character 0x00 quoted (+)
Character 0x21 quoted
Character 0x24 quoted
Character 0x28 quoted
Character 0x29 quoted
Character 0x2a quoted
Character 0x2b quoted
Character 0x2d quoted
Character 0x2e quoted
Character 0x3a quoted
Character 0x3c quoted
Character 0x3d quoted
Character 0x3e quoted
Character 0x3f quoted
Character 0x5b quoted
Character 0x5c quoted
Character 0x5d quoted
Character 0x5e quoted
Character 0x7b quoted
Character 0x7c quoted
Character 0x7d quoted

--- output ---
2017-08-26 02:53:57
http://php5.kiev.ua/manual/ru/function.preg-quote.html
It should be noted that the forward slash is not escaped.  Since many regexes are surrounded by forward slashes, if you have one in your regex as  text you must escape it yourself otherwise it'll terminat the regex.
2019-05-22 22:31:16
http://php5.kiev.ua/manual/ru/function.preg-quote.html
To have a higher level control of what your pattern looks like, try T-Regx:

Pattern::inject('This is (my|our) pattern: @', [$_GET['name']]);
2021-01-28 02:56:52
http://php5.kiev.ua/manual/ru/function.preg-quote.html
Автор:
I discovered that, in addition to escaping the special regular expression characters, preg_quote() encodes the NUL byte to its octal representation:

<?php
var_dump
(preg_quote("\0"));
?>

Output:

string(4) "\000"
2021-02-05 11:34:28
http://php5.kiev.ua/manual/ru/function.preg-quote.html

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