PHP Regex fails with '&' in string; passes (correctly) in javascript

Question

Running Linux (Ubuntu 11.10), the same regular expression works in JavaScript, but fails when & is included in the string being evaluated in PHP. Here's what I mean:

JavaScript regex:

regex = /^(?:[a-zA-Z0-9 ',.@&!+-]{3,50})$/;

PHP regex:

$settings['regex_name'] = "/^(?:[a-zA-Z0-9 ',.@&!+-]{3,50})$/";

When the code runs in a browser to verify a string (for example D & L Auto Sales), JavaScript matches the entire string as it should. However, when the server-side code attempts to match on the same string, it fails.

Has anyone run into this before?

EDIT: This is the PHP code that runs the regex:

function validated_array(&$array) {
    global $settings;

    $filterDefinitions = array( "name" => array('filter' => FILTER_VALIDATE_REGEXP,
                                'options' => array('regexp' => $settings['regex_name']),
        ...
    );


    $retVal = filter_var_array($array, $filterDefinitions);

When the code runs with D & L Auto Sales, $retVal['name'] is empty. However, when I remove the &, $retVal['name'] has a value.

As a general rule you can't assume that regular expressions will work identically in every scripting/programming language. In your case, I'm assuming there are different escape character requirements. — GoldenNewby
– GoldenNewby, Commented Feb 21, 2012 at 0:13
Works for me using preg_match(). How are you executing the regex match? — Phil
– Phil, Commented Feb 21, 2012 at 0:13
Not sure why this was down voted? Would it have helped if I had linked to us3.php.net/manual/en/regexp.reference.meta.php? — JoBu1324
– JoBu1324, Commented Feb 21, 2012 at 1:14

alex · Accepted Answer · 2012-02-21 01:04:48Z

2

Are you sure the & is not encoded as & in your HTML ?

Otherwise, Perl Compatible Regular Expressions have a high rate of compatibility between JavaScript and PHP (supported by both), and especially the one you gave in your example.

answered Feb 21, 2012 at 1:04

alex

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2 Comments

JoBu1324 Over a year ago

This is close enough to the problem: "name" comes from the URL, and it is decoded (turning & into &) for use in most of the javascript, so when I reuse the value in an ajax query, the & truncates the name short enough to fail validation. Thanks!

alex Over a year ago

@JoBu1324 No worries. Glad you figured it out.

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