A function that removes the HTML tags along with their contents.

strip_tags_content.php

<?php
/*
* This code belongs to a comment found in http://php.net/manual/en/function.strip-tags.php 
* by mariusz.tarnaski at wp dot pl 
**/
function strip_tags_content($text, $tags = '', $invert = FALSE) {

  preg_match_all('/<(.+?)[\s]*\/?[\s]*>/si', trim($tags), $tags);
  $tags = array_unique($tags[1]);
   
  if(is_array($tags) AND count($tags) > 0) {
    if($invert == FALSE) {
      return preg_replace('@<(?!(?:'. implode('|', $tags) .')\b)(\w+)\b.*?>.*?</\1>@si', '', $text);
    }
    else {
      return preg_replace('@<('. implode('|', $tags) .')\b.*?>.*?</\1>@si', '', $text);
    }
  }
  elseif($invert == FALSE) {
    return preg_replace('@<(\w+)\b.*?>.*?</\1>@si', '', $text);
  }
  return $text;
}
?>

Sample text:
$text = '<b>sample</b> text with <div>tags</div>';

Result for strip_tags($text):
sample text with tags

Result for strip_tags_content($text):
 text with

Result for strip_tags_content($text, '<b>'):
<b>sample</b> text with

Result for strip_tags_content($text, '<b>', TRUE);
 text with <div>tags</div>