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# preg_quote

(PHP 3>= 3.0.9, PHP 4 )

preg_quote -- 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.

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.

The special regular expression characters are:

    . \\ + * ? [ ^ ] $ ( ) { } = ! < > | :

Example 1.

    $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

    // 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);

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