字节转b kb mb gb 等

 /// <summary>
        /// 计算文件大小函数(保留两位小数),Size为字节大小
        /// </summary>
        /// <param name="size">初始文件大小</param>
        /// <returns></returns>
        public static string GetFileSize(long size)
        {
            var num = 1024.00; //byte
            if (size < num)
                return size + "B";
            if (size < Math.Pow(num, 2))
                return (size / num).ToString("f2") + "K"; //kb
            if (size < Math.Pow(num, 3))
                return (size / Math.Pow(num, 2)).ToString("f2") + "M"; //M
            if (size < Math.Pow(num, 4))
                return (size / Math.Pow(num, 3)).ToString("f2") + "G"; //G


            return (size / Math.Pow(num, 4)).ToString("f2") + "T"; //T
        }