c# 字节单位转换

public class ConvertSize
    {
        /// <summary>
        /// 获取
        /// </summary>
        /// <param name="b"></param>
        /// <returns></returns>
        public static string GetSize(double b)
        {

            String[] units = new String[] { "B", "KB", "MB", "GB", "TB", "PB" };
            double mod = 1024.0;
            int i = 0;
            while (b >= mod)
            {
                b /= mod;
                i++;
            }
            return Math.Round(b) + units[i];

        }

        /// <summary>
        /// 将B转换为TB
        /// </summary>
        /// <param name="b"></param>
        /// <returns></returns>
        private static string GetTB(long b)
        {
            for (int i = 0; i < 4; i++)
            {
                b /= 1024;
            }
            return b + "TB";
        }

        /// <summary>
        /// 将B转换为GB
        /// </summary>
        /// <param name="b"></param>
        /// <returns></returns>
        private static string GetGB(long b)
        {
            for (int i = 0; i < 3; i++)
            {
                b /= 1024;
            }
            return b + "GB";
        }

        /// <summary>
        /// 将B转换为MB
        /// </summary>
        /// <param name="b"></param>
        /// <returns></returns>
        private static string GetMB(long b)
        {
            for (int i = 0; i < 2; i++)
            {
                b /= 1024;
            }
            return b + "MB";
        }
    }
第二种保留2位小数
 /// <summary>
        /// 格式化文件大小的C#方法
        /// </summary>
        /// <param name="filesize">文件的大小,传入的是一个bytes为单位的参数</param>
        /// <returns>格式化后的值</returns>
        public static string ForematFileSize(long filesize)
        {
            if (filesize < 0)
            {
                return "0 b";
            }
            else if (filesize >= 1024 * 1024 * 1024) //文件大小大于或等于1024MB
            {
                return string.Format("{0:0.00} GB", (double)filesize / (1024 * 1024 * 1024));
            }
            else if (filesize >= 1024 * 1024) //文件大小大于或等于1024KB
            {
                return string.Format("{0:0.00} MB", (double)filesize / (1024 * 1024));
            }
            else if (filesize >= 1024) //文件大小大于等于1024bytes
            {
                return string.Format("{0:0.00} KB", (double)filesize / 1024);
            }
            else
            {
                return string.Format("{0:0.00} b", filesize);
            }
        }