/**
* Subtract character offset
*
* @param Char $char
*/
public function subtract(Char $char)
{
$this->ord -= $char->index();
$lower = $this->isLower() ? self::LOWERCASE_A : self::UPPERCASE_A;
if ($this->ord < $lower) {
$this->ord += self::CHAR_COUNT;
}
$this->char = chr($this->ord);
}
