obstart的小用法

<code>foreach (xx as x){
 $imgs.='<img  src="image/catalog/lazyload_grey.gif" data-original=".$tmp." image    style="max-width:90%"  style="max-width:90%" alt="obstart的小用法" >';
}
</code>

<code><?php ob_start();
    echo  '13712345678';
    echo 'another content<br>';
    $result=ob_get_contents();
    echo '<hr>';
    
    ob_clean();
  
    if(preg_match('/\d{11,}/', $result,$match)){
         echo str_replace(substr($match[0],-4),'****',$match[0]);
    }else{
        echo 'no match';
    }
    ob_end_flush();
    
    // result:1371234****
</code>