(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.
strThe 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.