文件容量单位转换

private string ConvertFileSizeUnit(double bytes)
        {
            if (bytes == 0)
            {
                return "0B";
            }
            int k = 1024;
            string[] unit = { "B", "KB", "MB", "GB" };
            int i = (int)Math.Floor(Math.Log(bytes) / Math.Log(k));
            double size = bytes / Math.Pow(k, i);
            return size + unit[i];
        }