在做项目的过程中，我们经常需要用到过滤一些html标签来实现提高数据的安全性，其实就是删除那些对应用程序有潜在危害的数据。它用于去除标签以及删除或编码不需要的字符。
首先分享一些比较常见的

$str=preg_replace("/<s*imgs+[^>]*?srcs*=s*('|")(.*?)\1[^>]*?/?s*>/i","", $str); //过滤img标签  
   
$str=preg_replace("/s+/","", $str); //过滤多余回车  
   
$str=preg_replace("/<[ ]+/si","<",$str); //过滤<__("<"号后面带空格)  
   
$str=preg_replace("/<!--.*?-->/si","",$str); //注释  
   
$str=preg_replace("/<(!.*?)>/si","",$str); //过滤DOCTYPE  
   
$str=preg_replace("/<(/?html.*?)>/si","",$str); //过滤html标签  
   
$str=preg_replace("/<(/?head.*?)>/si","",$str); //过滤head标签  
   
$str=preg_replace("/<(/?meta.*?)>/si","",$str); //过滤meta标签  
   
$str=preg_replace("/<(/?body.*?)>/si","",$str); //过滤body标签  
   
$str=preg_replace("/<(/?link.*?)>/si","",$str); //过滤link标签  
   
$str=preg_replace("/<(/?form.*?)>/si","",$str); //过滤form标签  
   
$str=preg_replace("/cookie/si","COOKIE",$str); //过滤COOKIE标签  
// http://www.manongjc.com/article/1345.html  
$str=preg_replace("/<(applet.*?)>(.*?)<(/applet.*?)>/si","",$str); //过滤applet标签  
   
$str=preg_replace("/<(/?applet.*?)>/si","",$str); //过滤applet标签  
   
$str=preg_replace("/<(style.*?)>(.*?)<(/style.*?)>/si","",$str); //过滤style标签  
   
$str=preg_replace("/<(/?style.*?)>/si","",$str); //过滤style标签  
   
$str=preg_replace("/<(title.*?)>(.*?)<(/title.*?)>/si","",$str); //过滤title标签  
   
$str=preg_replace("/<(/?title.*?)>/si","",$str); //过滤title标签  
   
$str=preg_replace("/<(object.*?)>(.*?)<(/object.*?)>/si","",$str); //过滤object标签  
   
$str=preg_replace("/<(/?objec.*?)>/si","",$str); //过滤object标签  
   
$str=preg_replace("/<(noframes.*?)>(.*?)<(/noframes.*?)>/si","",$str); //过滤noframes标签  
   
$str=preg_replace("/<(/?noframes.*?)>/si","",$str); //过滤noframes标签  
   
$str=preg_replace("/<(i?frame.*?)>(.*?)<(/i?frame.*?)>/si","",$str); //过滤frame标签  
   
$str=preg_replace("/<(/?i?frame.*?)>/si","",$str); //过滤frame标签  
   
$str=preg_replace("/<(script.*?)>(.*?)<(/script.*?)>/si","",$str); //过滤script标签  
   
$str=preg_replace("/<(/?script.*?)>/si","",$str); //过滤script标签  
   
$str=preg_replace("/java script/si","java script",$str); //过滤script标签  
   
$str=preg_replace("/vbscript/si","Vbscript",$str); //过滤script标签  
   
$str=preg_replace("/on([a-z]+)s*=/si","On\1=",$str); //过滤script标签  
   
$str=preg_replace("/&#/si","&＃",$str); //过滤script标签  

更简单些的写法：

function delhtml($str){  //清除html标签  
$st=-1; //开始  
$et=-1; //结束  
$stmp=array