- substr: documentation ( source)
- strpos: documentation ( source)
- implode: documentation ( source)
- preg_split: documentation ( source)
<?php
$path = '/a/b/c/d/config.ini';
$matches = preg_split('/\/|\\\/', $path);
$filename = $matches[count($matches) - 1];
$path = implode(DIRECTORY_SEPARATOR, $matches);
if(strpos($filename, '.') !== -1) {
$ext = substr($filename, strpos($filename, '.') + 1);
echo $ext;
}