php下过滤HTML代码的函数

/*----------------------
过滤HTML代码的函数
-----------------------*/
functionhtmlEncode($string){
$string=trim($string);
$string=str_replace("&","&",$string);
$string=str_replace("'","'",$string);
$string=str_replace("&","&",$string);
$string=str_replace(""",""",$string);
$string=str_replace(""",""",$string);
$string=str_replace("<","<",$string);
$string=str_replace("<","<",$string);
$string=str_replace(">",">",$string);
$string=str_replace(">",">",$string);
$string=str_replace("","",$string);
$string=nl2br($string);
return$string;
}