How to batch clear BOM in php files

//This file is used to quickly test whether the UTF8 encoded file has a BOM added and can be automatically removed
$basedir="."; //Modify the directory that needs to be detected for this behavior , the dot indicates the current directory
$auto=1; //Whether to automatically remove the discovered BOM information. 1 means yes, 0 means no.
//link: http://bbs.it-home.org
//No need to change the following
if ($dh = opendir($basedir)) {
while (($file = readdir($dh)) != = false) {
if ($file!='.' && $file!='..' && !is_dir($basedir."/".$file))
echo "filename: $file ".checkBOM(" $basedir/$file")." ";
}
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, $rest);
return ("BOM found, automatically removed.");
} else {
return ("BOM found.");
}
}else
return ("BOM Not Found.");
}
function rewrite ($filename, $data ) {
$filenum=fopen($filename,"w");
flock($filenum,LOCK_EX);
fwrite($filenum,$data);
fclose($filenum);
}
?>

2. Remove BOM codes from PHP files in batches

if (isset($_GET['dir'])){ //Set file directory
$basedir=$_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 "filename: $basedir/$file ".checkBOM("$basedir/$file")." ";
}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, $rest);
return ("BOM found, automatically removed._ http://bbs.it-home.org");
} else {
return ("BOM found.");
 }
}
else return ("BOM Not Found.");
}
function rewrite ($filename, $data) {
$filenum = fopen($filename, "w");
flock($filenum, LOCK_EX) ;
fwrite($filenum, $data);
fclose($filenum);
}
?>