<?php
class cls_string_filter{
 //將\n轉(zhuǎn)化為<br/>--囧，這有意思么？
 static public function nl2br($string){
  return nl2br($string);
 }
 //將<br/>轉(zhuǎn)化為\n
 static public function br2nl($string){
  $array = array('<br>','<br/>');
  return str_replace($array,"\n",$string);//字符串替換
 }
 //多個空格只保留一個
 static public function merge_spaces($string){
  return preg_replace("/\s(?=\s)/","\\1",$string);//(?=pattern)舉例：abc(?=kk)能匹配abckk，但不能匹配abcdd
 }
 //多個<br/>只保留一個
 static public function merge_brs($string){
  return preg_replace("/((<br\/?>)+)/i","<br>",$string);//---"/"為什么也轉(zhuǎn)義了
 }
 //過濾字符串中的html標簽
 static public function strip_tags($string){
  return strip_tags($string);
 }
 //將字符串轉(zhuǎn)換為小寫--/--大寫
 static public function strtolower($string){
  return strtolower($string);
 }
 static public function strtoupper($string){
  return strtoupper($string);
 }
 //過濾字符串開頭與結(jié)尾的特定字符
 static public function trim($string,$char_list='\\\\s'){
  $find = array('/[\^\-\]\\\]/S','/\\\{4}/S','/\//');
  $replace = array('\\\\\\0','\\','\/');
  $char = preg_replace($fine,$replace,$char_list);
  $pattern = '^['.$chars.']*|['.$chars.']';
  return preg_replace("/$pattern/sSD",'',$string);
 }
 //過濾字符串中<style>腳本
 static public function stric_style($string){
  $reg = "/<style[^>]*?>.*?<\/style>/is";
  return preg_replace($reg,'',$string);
 }
 //過濾字符串中html危險代碼
 static public function strip_html_tags($string){
  $reg = "/(\/?)/(script|iframe|style|html|body|title|meta|\?|\%)([^>]*?>)/is";
  return preg_replace($reg,'',$string);
 }
}
?>