I've seen lots of functions to convert all the entities, but I needed to do a fulltext search in a db field that had named entities instead of numeric entities (edited by tinymce), so I searched the tinymce source and found a string with the value->entity mapping. So, i wrote the following function to encode the user's query with named entities.

The string I used is different of the original, because i didn't want to convert ' or ". The string is too long, so I had to cut it. To get the original check TinyMCE source and search for nbsp or other entity ;)

<?php

$entities_unmatched = explode(',', '160,nbsp,161,iexcl,162,cent, [...] ');
$even = 1;
foreach($entities_unmatched as $c) {
    if($even) {
        $ord = $c;
    } else {
        $entities_table[$ord] = $c;
    }
    $even = 1 - $even;
}

function encode_named_entities($str) {
    global $entities_table;
    
    $encoded_str = '';
    for($i = 0; $i < strlen($str); $i++) {
        $ent = @$entities_table[ord($str{$i})];
        if($ent) {
            $encoded_str .= "&$ent;";
        } else {
            $encoded_str .= $str{$i};
        }
    }
    return $encoded_str;
}

?>