php 文件内大小单位转换

class unit {

    private static $units = [
        '0' => 'B',
        '1' => 'KB',
        '2' => 'MB',
        '3' => 'GB',
        '4' => 'TB',
        '5' => 'PB'
    ];

    //put your code here
    public static function getUnit(int $size): string {
        if ($size < 1) {
            return '0B';
        } elseif ($size < 1024) {
            return $size . 'B';
        }

        for ($i = 0; $size >= 1024 && $i < 5; $i++) {
            $size /= 1024;
        }
        return round($size, 2) . self::$units[$i];
    }

    public static function getSize(int $size, string $unit): int {
        if (!in_array($unit, self::$units)) {
            return $size;
        }
        $units = array_flip(self::$units);
        return $size * pow(1024, $units[$unit]);
    }

}