private function pad(string & $a, string & $b) : int
    {
        $x = \strlen($a);
        $y = \strlen($b);

        if ($x > $y) {
            $b = \str_repeat('0', $x - $y) . $b;

            return $x;
        }

        if ($x < $y) {
            $a = \str_repeat('0', $y - $x) . $a;

            return $y;
        }

        return $x;
    }
private function pad(string & $a, string & $b) : int
    {
        $x = \strlen($a);
        $y = \strlen($b);

        if ($x > $y) {
            $b = \str_repeat('0', $x - $y) . $b;

            return $x;
        }

        if ($x < $y) {
            $a = \str_repeat('0', $y - $x) . $a;

            return $y;
        }

        return $x;
    }
private function pad ( string & $ a , string & $ b ) : int { $ x = \ strlen ( $ a ) ; $ y = \ strlen ( $ b ) ; if ( $ x > $ y ) { $ b = \ str_repeat ( '0' , $ x - $ y ) . $ b ; return $ x ; } if ( $ x < $ y ) { $ a = \ str_repeat ( '0' , $ y - $ x ) . $ a ; return $ y ; } return $ x ; }
Pads the left of one of the given numbers with zeros if necessary to make both numbers the same length.

The numbers must only consist of digits, without leading minus sign.

@param string $a The first operand.
@param string $b The second operand.

@return int The length of both strings.
Pads the left of one of the given numbers with zeros if necessary to make both numbers the same length .