public static bool isValidFileContent(string filePath1, string filePath2)
       {
           //創建一個哈希算法對象
           using (HashAlgorithm hash = HashAlgorithm.Create())
           {
               using (FileStream file1 = new FileStream(filePath1, FileMode.Open),file2=new FileStream(filePath2,FileMode.Open))
               {
                   byte[] hashByte1 = hash.ComputeHash(file1);//哈希算法根據文本得到哈希碼的字節數組
                   byte[] hashByte2 = hash.ComputeHash(file2);
                   string str1 = BitConverter.ToString(hashByte1);//將字節數組裝換為字符串
                   string str2 = BitConverter.ToString(hashByte2);
                   return (str1==str2);//比較哈希碼
               }
           }
       }

static void Main(string[] args)
     {
         string filePath1 = @"f:/1.txt";
         string filePath2 = @"f:/2.txt";
         bool valid=isValidFileContent(filePath1, filePath2);
         Console.WriteLine(valid.ToString());
         Console.ReadKey();
     }