程序代码：

using System; 
using System.Collections.Generic; 
using System.Text; 
using  
 
namespace ConsoleApplication1 
{ 
    public class FileInvertedSequence 
    { 
        private FileStream stringFile; 
        private string fileName; 
 
        private string ReadStringInFile() 
        { 
            StreamReader sr = new StreamReader(stringFile); 
 
            string allString = sr.ReadToEnd(); 
            sr.Close(); 
            stringFile.Close(); 
            return allString; 
        } 
 
        //重新排序 
        public string InvertedSequenceString() 
        { 
            string orderString = ReadStringInFile(); 
            char[] chars = orderString.ToCharArray(); 
            StringBuilder sb = new StringBuilder(); 
 
            for (int i = chars.Length - 1; i >= 0; i--) 
            { 
                sb.Append(chars[i].ToString()); 
            } 
 
            return sb.ToString(); 
        } 
 
        public FileInvertedSequence(string FilePath) 
        { 
            this.fileName = FilePath; 
            this.stringFile = new FileStream(this.fileName, FileMode.Open); 
        } 
    } 
 
    class Program 
    { 
        static void Main(string[] args) 
        { 
            FileInvertedSequence test = new FileInvertedSequence("test.txt"); 
            Console.Write(test.InvertedSequenceString()); 
 
            Console.ReadKey(); 
        } 
    } 
}