Php批量去除bom头信息的实现代码

<?php 
/**
* 去除bom头信息
* edit: www.jb200.com
*/
header("Content-Type:text/html; charset=utf-8"); 
if (isset($_GET['dir'])){ //设置文件目录 
$basedir=$_GET['dir']; 
}else{ 
$basedir = '.'; 
} 
$auto = 1; 
checkdir($basedir); 
function checkdir($basedir){ 
if ($dh = opendir($basedir)) { 
  while (($file = readdir($dh)) !== false) { 
   if ($file != '.' && $file != '..'){ 
    if (!is_dir($basedir."/".$file)) { 
     echo "文件名称: $basedir/$file ".checkBOM("$basedir/$file")." <br>"; 
    }else{ 
     $dirname = $basedir."/".$file; 
     checkdir($dirname); 
    } 
   } 
  } 
closedir($dh); 
} 
} 
function checkBOM ($filename) { 
global $auto; 
$contents = file_get_contents($filename); 
$charset[1] = substr($contents, 0, 1); 
$charset[2] = substr($contents, 1, 1); 
$charset[3] = substr($contents, 2, 1); 
if (ord($charset[1]) == 239 && ord($charset[2]) == 187 && ord($charset[3]) == 191) { 
  if ($auto == 1) { 
   $rest = substr($contents, 3); 
   rewrite ($filename, $rest); 
   return ("<font color=red>发现BOM并且已自动删除</font>"); 
  } else { 
   return ("<font color=red>发现BOM</font>"); 
  } 
} 
else return ("没有发现BOM"); 
} 
function rewrite ($filename, $data) { 
$filenum = fopen($filename, "w"); 
flock($filenum, LOCK_EX); 
fwrite($filenum, $data); 
fclose($filenum); 
} 
?>