public function getExtension()
    {
        $pos = strrpos($this->name, '.');
        if ($pos === false) {
            return null;
        } else {
            return substr($this->name, $pos + 1);
        }
    }
public function getExtension()
    {
        $pos = strrpos($this->name, '.');
        if ($pos === false) {
            return null;
        } else {
            return substr($this->name, $pos + 1);
        }
    }
public function getExtension ( ) { $ pos = strrpos ( $ this -> name , '.' ) ; if ( $ pos === false ) { return null ; } else { return substr ( $ this -> name , $ pos + 1 ) ; } }
get extension if it's a blob

@return string|null
get extension if it s a blob