Here is a function i’ve used before, which works pretty well:
function closetags($html) {
preg_match_all('#<(?!meta|img|br|hr|input\b)\b([a-z]+)(?: .*)?(?<![/|/ ])>#iU', $html, $result);
$openedtags = $result[1];
preg_match_all('#</([a-z]+)>#iU', $html, $result);
$closedtags = $result[1];
$len_opened = count($openedtags);
if (count($closedtags) == $len_opened) {
return $html;
}
$openedtags = array_reverse($openedtags);
for ($i=0; $i < $len_opened; $i++) {
if (!in_array($openedtags[$i], $closedtags)) {
$html .= '</'.$openedtags[$i].'>';
} else {
unset($closedtags[array_search($openedtags[$i], $closedtags)]);
}
}
return $html;
}
Personally though, I would not do it using regexp but a library such as Tidy. This would be something like the following:
$str="<p>This is some text and here is a <strong>bold text then the post stop here....</p>";
$tidy = new Tidy();
$clean = $tidy->repairString($str, array(
'output-xml' => true,
'input-xml' => true
));
echo $clean;