递归函数只能在没有类的情况下工作，但不能在类中工作

I have a php code which performs directory/file listing. However, it does not work when called by object.

Following Code Works :

function getDirContents($dir, &$results = array()){
$files = scandir($dir);

foreach($files as $key => $value){
    $path = realpath($dir.DIRECTORY_SEPARATOR.$value);
    if(!is_dir($path)) {
        $results[] = $path;
    } else if($value != "." && $value != "..") {
        getDirContents($path, $results);
        $results[] = $path;
    }
}
// print_r($results);
return $results;
}

var_dump(getDirContents('C:\xampp\htdocs\skillup\d4a1'));

The following code DOES NOT work :

class Dira {
function getDirContents($dir, &$results = array()){
$files = scandir($dir);

foreach($files as $key => $value){
    $path = realpath($dir.DIRECTORY_SEPARATOR.$value);
    if(!is_dir($path)) {
        $results[] = $path;
    } else if($value != "." && $value != "..") {
        getDirContents($path, $results);
        $results[] = $path;
    }
}
// print_r($results);
return $results;
}

}

$obj = new Dira;
$arr = array();
var_dump($obj->getDirContents('C:\xampp\htdocs\skillup\d4a1'));

Your mistake is in your method, your method calls itself recursively via:

getDirContents();

but should do so like (in your Dira class):

$this->getDirContents();

You are using recursive function getDirContents() but when you call it again you are missing $this .

Try Below Example :

class abc{
    public function getDirContents($dir, &$results = array()){ 
    $files = scandir($dir);

        foreach($files as $key => $value){
            $path = realpath($dir.DIRECTORY_SEPARATOR.$value);
            if(!is_dir($path)) {
                $results[] = $path;
            } else if($value != "." && $value != "..") {
                $this->getDirContents($path, $results);
                $results[] = $path;
            }
        }
    return $results;
    }
}
$res = new abc();
$re = $res->getDirContents('YOUR PATH');
echo '<pre>'; print_r($re);