Using php to create a Folder select list - including child folders?

Question

I'm trying to use scandir to display a select list of folders listed in a specific directory (which works fine) however, I need it to also add the child folders (if there are any) into my select list. If anyone could help me, that would be great!

This is the structure I want:

<option>folder 1</option>
<option> --child 1</option>
<option> folder 2</option>
<option> folder 3</option>
<option> --child 1</option>
<option> --child 2</option>
<option> --child 3</option>

And this is the code I have (which only shows the parent folders) which I got from this thread (Using scandir() to find folders in a directory (PHP)):

 $dir = $_SERVER['DOCUMENT_ROOT']."\\folder\\";

 $path = $dir;
 $results = scandir($path);

 $folders = array();
 foreach ($results as $result) {
    if ($result == '.' || $result == '..') continue;
    if (is_dir($path . '/' . $result)) {
      $folders[] = $result;
    };
 };

^^ but I need it to show the child directories also. I don't want the files, only the folders.

Answer 1

/* FUNCTION: showDir
 * DESCRIPTION: Creates a list options from all files, folders, and recursivly
 *     found files and subfolders. Echos all the options as they are retrieved
 * EXAMPLE: showDir(".") */
function showDir( $dir , $subdir = 0 ) {
    if ( !is_dir( $dir ) ) { return false; }

    $scan = scandir( $dir );

    foreach( $scan as $key => $val ) {
        if ( $val[0] == "." ) { continue; }

        if ( is_dir( $dir . "/" . $val ) ) {
            echo "<option>" . str_repeat( "--", $subdir ) . $val . "</option>\n";

            if ( $val[0] !="." ) {
                showDir( $dir . "/" . $val , $subdir + 1 );
            }
        }
    }

    return true;
}