今天在網上看到了一個比較細致的php正則表達式過濾html標簽代碼，就摘錄了下來。最常用正則表達式過濾代碼，能夠幫你過濾多余回車，注釋，html標簽等。
$str=preg_replace("/\s+/", " ", $str); //過濾多余回車
$str=preg_replace("/<[ ]+/si","<",$str); //過濾<__("<"號后面帶空格)
$str=preg_replace("/<\!--.*?-->/si","",$str); //注釋
$str=preg_replace("/<(\!.*?)>/si","",$str); //過濾DOCTYPE
$str=preg_replace("/<(\/?html.*?)>/si","",$str); //過濾html標簽
$str=preg_replace("/<(\/?head.*?)>/si","",$str); //過濾head標簽
$str=preg_replace("/<(\/?meta.*?)>/si","",$str); //過濾meta標簽
$str=preg_replace("/<(\/?body.*?)>/si","",$str); //過濾body標簽
$str=preg_replace("/<(\/?link.*?)>/si","",$str); //過濾link標簽
$str=preg_replace("/<(\/?form.*?)>/si","",$str); //過濾form標簽
$str=preg_replace("/cookie/si","COOKIE",$str); //過濾COOKIE標簽
$str=preg_replace("/<(applet.*?)>(.*?)<(\/applet.*?)>/si","",$str); //過濾applet標簽
$str=preg_replace("/<(\/?applet.*?)>/si","",$str); //過濾applet標簽
$str=preg_replace("/<(style.*?)>(.*?)<(\/style.*?)>/si","",$str); //過濾style標簽
$str=preg_replace("/<(\/?style.*?)>/si","",$str); //過濾style標簽
$str=preg_replace("/<(title.*?)>(.*?)<(\/title.*?)>/si","",$str); //過濾title標簽
$str=preg_replace("/<(\/?title.*?)>/si","",$str); //過濾title標簽
$str=preg_replace("/<(object.*?)>(.*?)<(\/object.*?)>/si","",$str); //過濾object標簽
$str=preg_replace("/<(\/?objec.*?)>/si","",$str); //過濾object標簽
$str=preg_replace("/<(noframes.*?)>(.*?)<(\/noframes.*?)>/si","",$str); //過濾noframes標簽
$str=preg_replace("/<(\/?noframes.*?)>/si","",$str); //過濾noframes標簽
$str=preg_replace("/<(i?frame.*?)>(.*?)<(\/i?frame.*?)>/si","",$str); //過濾frame標簽
$str=preg_replace("/<(\/?i?frame.*?)>/si","",$str); //過濾frame標簽
$str=preg_replace("/<(script.*?)>(.*?)<(\/script.*?)>/si","",$str); //過濾script標簽
$str=preg_replace("/<(\/?script.*?)>/si","",$str); //過濾script標簽
$str=preg_replace("/javascript/si","Javascript",$str); //過濾script標簽
$str=preg_replace("/vbscript/si","Vbscript",$str); //過濾script標簽
$str=preg_replace("/on([a-z]+)\s*=/si","On\\1=",$str); //過濾script標簽
$str=preg_replace("/&#/si","&＃",$str); //過濾script標簽，如javAsCript:alert(