常用正则

$str = '<div id="test">'.
            '<div>1'.                
                '<div>1-1'.                    
                    '<div>1-1-1'.                        
                    '</div>'.
                '</div>'.
            '</div>'.
            '<div>2</div>'.
            '<span>3</span>'.
            '<div>4</div>'.
        '</div>';
            
$regex = "/<div.*?id=\"test\".*?>(<.*?>.*?<\/.*?>){0,10}<\/div>/is";
preg_match ( $regex, $str, $m );  
print_r($m);

echo preg_replace('~[^\p{Han}]~u', '', '2tyyyyys23你是【你好！】'),"\n";

$a = "<tt>som在线冲值e</tt><b>ht打算ml</b>";
$result = preg_replace('/([\x80-\xff]*)/i','',$a);
echo $result;

$pattern = "/<img.*?src=[\"|\'](.*?)[\"|\'].*?alt=[\"|\'](.*?)[\"|\'].*?>/";