PHP清理字符串中所有无用标签

function Bing_string_cleanr( $string ){ 
$string = trim( $string );  
$string = strip_tags( $string ); 
$string = htmlspecialchars( $string, ENT_QUOTES, 'UTF-8' ); 
$string = str_replace( "n", "", $string ); 
$string = trim( $string ); 
return $string; 
}

<?php 
$str = " This line containstliberal rn use of whitespace.nn"; 
 
// First remove the leading/trailing whitespace 
//去掉开始和结束的空白 
$str = trim($str); 
 
// Now remove any doubled-up whitespace 
//去掉跟随别的挤在一块的空白 
$str = preg_replace(&#39;/s(?=s)/&#39;, &#39;&#39;, $str); 
 
// Finally, replace any non-space whitespace, with a space 
//最后，去掉非space 的空白，用一个空格代替 
$str = preg_replace(&#39;/[nrt]/&#39;, &#39; &#39;, $str); 
//开源代码phprm.com 
// Echo out: &#39;This line contains liberal use of whitespace.&#39; 
echo "<pre class="brush:php;toolbar:false">{$str}