How to close unclosed HTML Tags?

Question

Whenever we are fetching some user inputed content with some editing from the database or similar sources, we might retrieve the portion which only contains the opening tag

Answer 1

A better PHP function to delete not open/not closed tags from webmaster-glossar.de (me)

function closetag($html){
    $html_new = $html;
    preg_match_all ( "#<([a-z]+)( .*)?(?!/)>#iU", $html, $result1);
    preg_match_all ( "##iU", $html, $result2);
    $results_start = $result1[1];
    $results_end = $result2[1];
    foreach($results_start AS $startag){
        if(!in_array($startag, $results_end)){
            $html_new = str_replace('<'.$startag.'>', '', $html_new);
        }
    }
    foreach($results_end AS $endtag){
        if(!in_array($endtag, $results_start)){
            $html_new = str_replace('', '', $html_new);
        }
    }
    return $html_new;
}

use this function like:

closetag('i love my cat'); 
#output: i love my cat

closetag('i love my cat'); 
#output: i love my cat