How to sort the contents of a directory alphabetically with sub directorys appearing before normal files?

Question

I need to sort the contents of a directory in ascending order (alphabetically). The directories must appear before files even if the directory's name would appear after a files name (alphabetically). The same way file explorers do, they list directories sorted then they list the files sorted.

I am using the following code which gives me a sorted list alphabetically but it does not advances the directories first:

if($handler = opendir($dir))
{
    while (($sub = readdir($handler)) !== FALSE)
    {
        // ...
    }    
    closedir($handler); 
}

Answer 1

A straightforward way to achieve that would be to populate an array with pairs like [is_file(path), path], sort this array (php will automatically sort by the first and then by the second element) and finally remove the is_file bit:

$path = 'somedir';
$dir = [];

// populate
foreach(glob("$path/*") as $f)
    $dir []= [is_file($f), $f];

// sort
sort($dir);

// remove
$dir = array_map('end', $dir);

// PROFIT
print_r($dir);