- substr: documentation ( source)
- pathinfo: documentation ( source)
<?php
$href = "/test/link";
$file = "/media/doc/doc.pdf";
echo substr($href, -1, 1), PHP_EOL;
echo pathinfo($href, PATHINFO_EXTENSION), PHP_EOL;
echo substr($file, -1, 1), PHP_EOL;
echo pathinfo($file, PATHINFO_EXTENSION), PHP_EOL;