php字符串过滤与替换小结

<?php
class cls_string_filter{
?//将n转化为<br/>--澹庥幸馑济矗
?static public function nl2br($string){
? return nl2br($string);
?}
?//将<br/>转化为n
?static public function br2nl($string){
? $array = array('<br>','<br/>');
? return str_replace($array,"n",$string);//字符串替换
?}
?//多个空格只保留一个
?static public function merge_spaces($string){
? return preg_replace("/s(?=s)/","1",$string);//(?=pattern)举例：abc(?=kk)能匹配abckk,但不能匹配abcdd
?}
?//多个<br/>只保留一个
?static public function merge_brs($string){
? return preg_replace("/((<br/?>)+)/i","<br>",$string);//---"/"为什么也转义了
?}
?//过滤字符串中的html标签
?static public function strip_tags($string){
? return strip_tags($string);
?}
?//将字符串转换为小写--/--大写
?static public function strtolower($string){
? return strtolower($string);
?}
?static public function strtoupper($string){
? return strtoupper($string);
?}
?//过滤字符串开头与结尾的特定字符
?static public function trim($string,$char_list='\s'){
? $find = array('/[^-]]/S','/{4}/S','///');
? $replace = array('\','','/');
? $char = preg_replace($fine,$replace,$char_list);
? $pattern = '^['.$chars.']*|['.$chars.']';
? return preg_replace("/$pattern/sSD",'',$string);
?}
?//过滤字符串中<style>脚本
?static public function stric_style($string){
? $reg = "/<style[^>]*?>.*?</style>/is";
? return preg_replace($reg,$string);
?}
?//过滤字符串中html危险代码
?static public function strip_html_tags($string){
? $reg = "/(/?)/(script|iframe|style|html|body|title|meta|?|%)([^>]*?>)/is";
? return preg_replace($reg,$string);
?}
}
?>