private function toBinary(string $number) : string
    {
        $result = '';

        while ($number !== '0') {
            [$number, $remainder] = $this->divQR($number, '256');
            $result .= \chr((int) $remainder);
        }

        return \strrev($result);
    }
private function toBinary(string $number) : string
    {
        $result = '';

        while ($number !== '0') {
            [$number, $remainder] = $this->divQR($number, '256');
            $result .= \chr((int) $remainder);
        }

        return \strrev($result);
    }
private function toBinary ( string $ number ) : string { $ result = '' ; while ( $ number !== '0' ) { [ $ number , $ remainder ] = $ this -> divQR ( $ number , '256' ) ; $ result .= \ chr ( ( int ) $ remainder ) ; } return \ strrev ( $ result ) ; }
Converts a decimal number to a binary string.

@param string $number The number to convert, positive or zero, only digits.

@return string
Converts a decimal number to a binary string .