PHP, convert $_GET elements to HTML entities - php

Question

Edit: I think %27 is actually the wrong kind of quote. I am still stuck though, I cannot find a PHP function that does the conversion I want.
Edit (again): I found a solution where I stick %26rsquo%3bs into the URL and it turns into ’. It works so I posted it as an answer below but I'd still be interested in knowing how it'd be done with PHP functions.
I'm working on a website that uses a PHP tree as if it were a directory. For example, if someone types index.php?foo=visual programming (or index.php?foo=visual%20programming) then the website opens the item "Visual Programming" (I'm using strtolower()).
Another working example would be index.php?foo=visual programming&bar=animated path finder which opens "Animated Path Finder", a child of "Visual Programming".
The problem is that some of the items are named things like "Conway’s Game of Life" which uses a HTML entity. My guess of what someone should type to open this would be index.php?foo=visual%20programming&bar=conway%27s%20game%20of%20life. The problem is that ' is not === to ’.
What do I need to do to make this work? Here is my code that selects an item based on $_GET (the PHP is inside of <script type="text/javascript">):
<?php
function echoActiveDirectory($inTree) {
// Compare $_GET with PhpTree
$itemId = 0;
foreach ($_GET as $name) {
if ($inTree->children !== null) {
foreach ($inTree->children as $child) {
if (strtolower($child->title) === strtolower($name)) {
$itemId = $child->id;
$inTree = $child;
break;
}
}
}
}
// Set jsItems[$itemId].selected(), it will be 0 if nothing was found
echo "\t\tjsItems[".$itemId."].selected();\n";
}
echo "// Results of PHP echoActiveDirectory(\$root)\n";
echoActiveDirectory($root);
?>
The website is a work in progress, but it can be tested here to see $_GET working: http://alexsimes.com/index.php

Answer 1

The hex code %27 (39 decimal) will never translate to ’, since it is a completely different entity (Wikipedia). It could be translated to ', but PHP doesn't do that (although I don't know the reason for that).
Edit
While there is no standard for URL-encoding multibyte character sets, PHP will treat a string as just a set of bytes, and if those match an UTF-8 sequence, it will work:
php -r 'echo htmlentities(urldecode("%E2%80%99"), ENT_QUOTES|ENT_HTML401);'
should output
’

Answer 2

You can use html_entity_encode() and html_entity_decode() PHP functions to convert those characters to html entities or decode them back to desired characters before comparison.

Answer 3

You can try the htmlentities function to convert special characters to corresponding html entity. But in your case if data is already stored in db as html entity form, the data from $_GET parameter must be first passed through htmlentities before using it in your query.