PHP: Quote regular expression characters

Description

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

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 string.

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.