C#获取文件的大小

   （1）获取文件的字节长度
        /// <summary>
        /// 获取文件大小
        /// </summary>
        /// <param name="sFullName"></param>
        /// <returns></returns>
        public static long GetFileSize(string sFullName)
        {
            long lSize = 0;
            if (File.Exists(sFullName))
                lSize = new FileInfo(sFullName).Length;
            return lSize;
        }

   （2）将文件的字节长度转换为实际应用中的大小
    这里是一个计算方法：
    /// <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 CountSize(long Size)
        {
            string m_strSize = "";
            long FactSize = 0;
            FactSize = Size;
            if (FactSize < 1024.00)
                m_strSize = FactSize.ToString("F2") + " Byte";
            else if (FactSize >= 1024.00 && FactSize < 1048576)
                m_strSize = (FactSize / 1024.00).ToString("F2") + " K";
            else if (FactSize >= 1048576 && FactSize < 1073741824)
                m_strSize = (FactSize / 1024.00 / 1024.00).ToString("F2") + " M";
            else if (FactSize >= 1073741824)
                m_strSize = (FactSize / 1024.00 / 1024.00 / 1024.00).ToString("F2") + " G";
            return m_strSize;
        }