PHP traverses the files in the folder and obtains the value of the input name, _PHP tutorial

PHP traverses the files in the folder and obtains the value of the input name,

$dir = dirname(__FILE__); //To be traversed Directory name->The folder where the current file is located
//$dir='D:PHPwampwwwadminhostsadmin';
//PHP traverses all files in the folder
$handle=opendir($dir.". ");
$arr = array();
while($file=readdir($handle)){
　if(is_file($file)){
　if ($file != " ."&& $file != "..") {
　 $file = mb_substr($file,0,strripos($file,'.'));
$files = explode(' ',$file ); //Convert $file into an array
　　$arr[]=$files['0'];//Convert into a one-dimensional array
　　}
　}
}
//print_r ($arr);
closedir($handle);
//PHP gets the value of input->name
foreach ($_POST AS $key=>$value){
　if( !in_array($key,$arr)){ //Check whether the name value is in $arr
　 echo "$key: does not exist";
}

}
?>