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REGEX: Convert & to & only in double entities

Posted on 2008-10-24
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Last Modified: 2009-01-23
Hello,

For security reasons, and to maintain data I now use htmlentities() to clean user-managed settings before placing the values in form input fields.

The problem is that © becomes ©

I wrote a function to fix this but it changes ALL & to & and I only want to change & to & if it is part of an html entity.

So these should be changed
            <
            ©
            ÷
            À
            "
            ©
            ©
            €

But these should NOT be changed:

            This is a test & only a test.
            dsafdsf&adsfdsf
            &€
            &&

function clean_htmlentities ($str) {
return str_replace(array('&','&'),'&',htmlentities($str));
}

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Question by:hankknight
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6 Comments
 
LVL 27

Expert Comment

by:yodercm
ID: 22795727
I think you should be using the double_encode in the htmlentities function.  See here for details....

http://us2.php.net/manual/en/function.htmlentities.php
0
 
LVL 27

Expert Comment

by:yodercm
ID: 22795743
By the way, double_encode is only available in php 5, so be sure you are up to date in your php version.  :)
0
 
LVL 16

Author Comment

by:hankknight
ID: 22795846
This has to be PHP4 compatible
:-(


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LVL 27

Expert Comment

by:yodercm
ID: 22796052
Go to that manual page for htmlentities, and read through the user posted comments below.  You may find some ideas that will help you, such as

http://us2.php.net/manual/en/function.htmlentities.php#70850

http://us2.php.net/manual/en/function.htmlentities.php#48131

I haven't tried any of these, but maybe you can make one of them work for your needs.
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LVL 51

Accepted Solution

by:
ahoffmann earned 500 total points
ID: 22804728
the raw regex

(?:&([#x]\d+|[a-zA-Z\d-]+))

then you can prepend the returnd match by &
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LVL 16

Author Comment

by:hankknight
ID: 22825697
How could my function be replaced with this regex?
(?:&([#x]\d+|[a-zA-Z\d-]+))
function clean_htmlentities ($str) {
return str_replace(array('&','&'),'&',htmlentities($str));
}

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