The two default flags are zero (virtual) as with my PHP versions (5.3 and 5.4). Which means you can not check if those are set or not with the & bitwise operator:
<?php
$directoryIterator->getFlags() & RecursiveDirectoryIterator::CURRENT_AS_FILEINFO;
?>
But this also allows that you can use other flags right ahead without repeating the default ones:
<?php
new RecursiveDirectoryIterator(
'.',
FilesystemIterator::UNIX_PATHS
);
?>
There is no need to repeat the default flags. Please note that this is different to FilesystemIterator which has as well the SKIP_DOTS flag as default which is non-zero:
<?php
new RecursiveDirectoryIterator(
'.',
FilesystemIterator::SKIP_DOTS
| FilesystemIterator::UNIX_PATHS
);
?>