c# ASCII转换，数字转字母，字母转数字

//数字转字母
        public string chr(int asciiCode)
        {
            if (asciiCode >= 0 && asciiCode <= 255)
            {
                System.Text.ASCIIEncoding asciiEncoding = new System.Text.ASCIIEncoding();
                byte[] byteArray = new byte[] { (byte)asciiCode };
                string strCharacter = asciiEncoding.GetString(byteArray);
                return (strCharacter);
            }
            else
            {
                throw new Exception("ASCII Code is not valid.");
            }
        }
        //字母转数字
        public int ord(string c)
        {
            byte[] array = new byte[1];   //定义一组数组array
            array = System.Text.Encoding.ASCII.GetBytes(c); //string转换的字母
            int asciicode = (short)(array[0]);
            //ASCII码 = Convert.ToString(asciicode); //将转换一的ASCII码转换成string型
            return asciicode;
        }