How can the presence of hidden directories like '.' and '..' affect the results of checking for files in a folder using PHP?

The presence of hidden directories like '.' and '..' can affect the results of checking for files in a folder using PHP because these directories are included in the list of files returned by functions like scandir(). To solve this issue, you can filter out these directories from the list of files by using the array_filter() function with a custom callback function.

$files = array_filter(scandir($directory), function($file) {
    return !in_array($file, ['.', '..']);
});