PHP function to remove useless formats pasted directly from word

function ClearHtml($content,$allowtags='') {
mb_regex_encoding('UTF-8');
//replace MS special characters first
$search = array('/‘/u', '/’/u', '/“/u', '/”/u', '/—/u');
$replace = array(''', ''', '"', '"', '-');
$content = preg_replace($search, $replace, $content);
//make sure _all_ html entities are converted to the plain ascii equivalents - it appears
//in some MS headers, some html entities are encoded and some aren't
$content = html_entity_decode($content, ENT_QUOTES, 'UTF-8');
//try to strip out any C style comments first, since these, embedded in html comments, seem to
//prevent strip_tags from removing html comments (MS Word introduced combination)
if(mb_stripos($content, '/*') !== FALSE){
$content = mb_eregi_replace('#/*.*?*/#s', '', $content, 'm');
}
//introduce a space into any arithmetic expressions that could be caught by strip_tags so that they won't be
//'<1' becomes '< 1'(note: somewhat application specific)
$content = preg_replace(array('/<([0-9]+)/'), array('< $1'), $content);
$content = strip_tags($content, $allowtags);
//eliminate extraneous whitespace from start and end of line, or anywhere there are two or more spaces, convert it to one
$content = preg_replace(array('/^ss+/', '/ss+$/', '/ss+/u'), array('', '', ' '), $content);
//strip out inline css and simplify style tags
$search = array('#<(strong|b)[^>]*>(.*?)#isu', '#<(em|i)[^>]*>(.*?)#isu', '#]*>(.*?)#isu');
$replace = array('$2', '$2', '$1');
$content = preg_replace($search, $replace, $content);
//on some of the ?newer MS Word exports, where you get conditionals of the form 'if gte mso 9', etc., it appears
//that whatever is in one of the html comments prevents strip_tags from eradicating the html comment that contains
//some MS Style Definitions - this last bit gets rid of any leftover comments */
$num_matches = preg_match_all("//isu', '', $content);
}
return $content;
}
?>

测试：

$content = '
《优伴户外旅行》——让旅行成为习惯！越发忙碌的你，是否想给自己放个假？专注工作的你，是否还记得上一次锻炼是什么时候？优伴户外旅行，给你不一样的旅行体验：给心自由，便处处都是风景！';
echo ClearHtml($content,'');
/*
得到的结果：
《优伴户外旅行》--让旅行成为习惯！越发忙碌的你，是否想给自己放个假？专注工作的你，是否还记得上一次锻炼是什么时候？优伴户外旅行，给你不一样的旅行体验：给心自由，便处处都是风景！
*/
?>