- substr: documentation ( source)
- strcspn: documentation ( source)
- strpos: documentation ( source)
- dirname: documentation ( source)
- strtok: documentation ( source)
<?php
$test = '/privateavatar/3de0948dc257e0a62d3a970eca5d6be0/Filename.png';
echo '#' . substr($test, 1, strcspn($test, '/', 1)) . '#', "\n";
echo '#' . substr($test, 1, strpos($test, '/', 1) - 1) . '#', "\n";
echo '#' . substr(dirname(dirname($test)), 1) . '#', "\n";
echo '#' . strtok($test, '/') . '#', "\n";