字元型別轉換

char

  char[] digits = "0123456789abcdef".ToCharArray();

int

   （1）使用強制型別轉換：(int)浮點數 

   （2）使用Convert.ToInt32(string)

   （3）使用 int.Parse(string) 或 int.TryParse(string,out int)

 

在實際使用時，當要轉換的字串或數字帶有小數時，發現它們有以下區別：

   （1）方法一:截斷  方法二:四捨五入 　　int a=(int)2.8; //結果為2 　　int b=Convert.ToInt32(2.8); //b的值為3

　（2）int.Parse方法的引數如果不能轉換為整數，則報異常。 如 int c=int.Parse("2.8"); //報異常,說明其引數必須是整數字符串

//int.TryParse

int c = -1;  　 

int.TryParse("2.8", out c); //不能轉換成功，結果為0 　　

int.TryParse("2", out c); //轉換成功，結果為2

 string to int

int a = (int)'a'; //結果為97，注意是字元，而不是字串（如果是字串，編譯不能通過）         

int b = Convert.ToInt32("a"); //報異常 

int c=int.Parse("a");  //報異常

int d = -1;         

int.TryParse("a", out d); //結果為0

 可變字串

string[] HexPadding = new string[16];

int padding = HexPadding.Length - i;

 var buf = new StringBuilder(padding * 3);

buf.Append("   ");

 

 

 

 

byte[] + byte[]

 /// <summary>
        /// 拼接二進位制陣列
        /// </summary>
        /// <param name="buffer1"></param>
        /// <param name="buffer2"></param>
        /// <returns></returns>
        public static byte[] Joint(byte[] buffer1, byte[] buffer2)
        {
            byte[] bufferWhole = new byte[buffer1.Length + buffer2.Length];
            Buffer.BlockCopy(buffer1, 0, bufferWhole, 0, buffer1.Length);
            Buffer.BlockCopy(buffer2, 0, bufferWhole, buffer1.Length, buffer2.Length);
            return bufferWhole;
        }

        public static byte[] Joint(byte[] buffer1, byte[] buffer2, byte[] buffer3)
        {
            return BufferJointer.Joint(BufferJointer.Joint(buffer1, buffer2), buffer3);
        }

        public static byte[] Joint(byte[] buffer1, byte[] buffer2, byte[] buffer3, byte[] buffer4)
        {
            return BufferJointer.Joint(BufferJointer.Joint(buffer1, buffer2, buffer3), buffer4);
        }

        public static byte[] Joint(byte[] buffer1, byte[] buffer2, byte[] buffer3, byte[] buffer4, byte[] buffer5, byte[] buffer6)
        {
            return BufferJointer.Joint(BufferJointer.Joint(buffer1, buffer2, buffer3, buffer4), buffer5, buffer6);
        }     

 string to byte[] to uft-8

   public static string get_uft8(string unicodeString)
   {
       UTF8Encoding utf8 = new UTF8Encoding();
       Byte[] encodedBytes = utf8.GetBytes(unicodeString);
       String decodedString = utf8.GetString(encodedBytes);
       return decodedString;
    }

 

 

 

 

 

 

  class FileHelper
    {
        // 首先引用API 函式  

        [DllImport("kernel32.dll")]
        private static extern IntPtr _lopen(string lpPathName, int iReadWrite);
        [DllImport("kernel32.dll")]
        private static extern bool CloseHandle(IntPtr hObject);
        private const int OF_READWRITE = 2;
        private const int OF_SHARE_DENY_NONE = 0x40;
        private readonly IntPtr HFILE_ERROR = new IntPtr(-1);


        /// <summary>   
        /// 檢查檔案是否已經開啟   
        /// </summary>   
        /// <param name="strfilepath">要檢查的檔案路徑</param>          
        /// <returns>-1檔案不存在,1檔案已經開啟,0檔案可用未開啟</returns>   
        public FileStatus VerifyFileIsOpen(string strfilepath)
        {
            string vFileName = strfilepath;

            // 先檢查檔案是否存在,如果不存在那就不檢查了   
            if (!File.Exists(vFileName))
            {
                return FileStatus.Inexistence;
            }

            // 開啟指定檔案看看情況   
            IntPtr vHandle = _lopen(vFileName, OF_READWRITE | OF_SHARE_DENY_NONE);
            if (vHandle == HFILE_ERROR)
            { // 檔案已經被開啟                   
                return FileStatus.Opened;
            }
            CloseHandle(vHandle);

            // 說明檔案沒被開啟，並且可用  

            return FileStatus.Untapped;
        }
    }