C＃：优惠券代码

 static Random random = new Random();
        List<string> generatedVouchers = new List<string>();
        char[] keys = "ABCDEFGHIJKLMNOPQRSTUVWXYZ01234567890".ToCharArray(); 

        private static string GenerateVoucher(char[] keys, int lengthOfVoucher)
        {
         return Enumerable
        .Range(, lengthOfVoucher) // for(i.. )
        .Select(k => keys[random.Next(, keys.Length - )]) // generate a new random char
        .Aggregate("", (e, c) => e + c); // join into a string
        }

        protected void Page_Load(object sender, EventArgs e)
        {
            if (!IsPostBack)
            {
                int vouchersToGenerate = ;
                int lengthOfVoucher = ;

                List<string> generatedVouchers = new List<string>();
                char[] keys = "".ToCharArray();

                //while (generatedVouchers.Count < vouchersToGenerate)
                //{
                //    var voucher = GenerateVoucher(keys, lengthOfVoucher);
                //    if (!generatedVouchers.Contains(voucher))
                //    {
                //        generatedVouchers.Add(voucher);
                //        Response.Write(string.Format("<br>[#{0}] {1}", generatedVouchers.Count, voucher));
                //    }
                //}

                string vCode = GenerateVoucher(keys, lengthOfVoucher);
                Response.Write("<br>" + string.Format("{0}-{1}-{2}",
                         vCode.Substring(, ),
                         vCode.Substring(, ),
                         vCode.Substring(, )));

                //Response.Write("<br>" + string.Format("{0}", vCode.Substring(0, 4)));
                //Response.Write("<br>" + string.Format("{0}", vCode.Substring(4, 4)));
                //Response.Write("<br>" + string.Format("{0}", vCode.Substring(8, 4)));

                Response.Write("<br>-------------------------------------------------------------------<br>");

                //**********************************************************************************************
                Random random = new Random();
                DateTime timeValue = DateTime.MinValue;
                System.Text.Encoding big5 = System.Text.Encoding.GetEncoding("big5");
                System.Text.Encoding gb2312 = System.Text.Encoding.GetEncoding("gb2312");

                // Create 10 codes just to see the random generation.
                for (int i = ; i < ; ++i)
                {
                    int rand = random.Next();
                    timeValue = timeValue.AddMinutes(rand);
                    byte[] buffer = System.BitConverter.GetBytes(timeValue.Ticks);
                    string voucherCode = ToBase32String(buffer); //BitConverter.ToString(buffer);
                    Response.Write("<br>" + string.Format("{0}-{1}-{2}",
                         voucherCode.Substring(, ),
                         voucherCode.Substring(, ),
                         voucherCode.Substring(, )));
                }
                Response.Write("<br>-------------------------------------------------------------------<br>");

                //**********************************************************************************************

                //System.Guid g = System.Guid.NewGuid();
                //Random rn = new Random();
                //string gs = g.ToString();
                //int randomInt = rn.Next(5, 10 + 1);
                //Response.Write("<br>" + gs.Substring(gs.Length - randomInt - 1, randomInt));
            }
        }

        public static string ToBase32String(byte[] input)
        {
            if (input == null || input.Length == )
            {
                throw new ArgumentNullException("input");
            }

            int charCount = (int)Math.Ceiling(input.Length / 5d) * ;
            char[] returnArray = new char[charCount];

            byte nextChar = , bitsRemaining = ;
            int arrayIndex = ;

            foreach (byte b in input)
            {
                nextChar = (byte)(nextChar | (b >> ( - bitsRemaining)));
                returnArray[arrayIndex++] = ValueToChar(nextChar);

                if (bitsRemaining < )
                {
                    nextChar = (byte)((b >> ( - bitsRemaining)) & );
                    returnArray[arrayIndex++] = ValueToChar(nextChar);
                    bitsRemaining += ;
                }

                bitsRemaining -= ;
                nextChar = (byte)((b << bitsRemaining) & );
            }

            //if we didn't end with a full char
            if (arrayIndex != charCount)
            {
                returnArray[arrayIndex++] = ValueToChar(nextChar);
                while (arrayIndex != charCount) returnArray[arrayIndex++] = '='; //padding
            }

            return new string(returnArray);
        }
        private static int CharToValue(char c)
        {
            int value = (int)c;

            //65-90 == uppercase letters
            if (value <  && value > )
            {
                return value - ;
            }
            //50-55 == numbers 2-7
            if (value <  && value > )
            {
                return value - ;
            }
            //97-122 == lowercase letters
            if (value <  && value > )
            {
                return value - ;
            }

            throw new ArgumentException("Character is not a Base32 character.", "c");
        }
        private static char ValueToChar(byte b)
        {
            if (b < )
            {
                return (char)(b + );
            }

            if (b < )
            {
                return (char)(b + );
            }

            throw new ArgumentException("Byte is not a value Base32 value.", "b");
        }