(PHP 4, PHP 5, PHP 7, PHP 8)
preg_quote — Quote regular expression characters
$str
, ?string $delimiter
= null
): string
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:
. \ + * ? [ ^ ] $ ( ) { } = ! < > | : - #
Note that /
is not a special regular expression character.
Note:
Note that preg_quote() is not meant to be applied to the $replacement string(s) of preg_replace() etc.
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.
Returns the quoted (escaped) string.
Version | Description |
---|---|
7.3.0 |
The # character is now quoted
|
7.2.0 |
delimiter is nullable now.
|
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);
?>
Note: This function is binary-safe.