How to Generate Alphanumeric Codes

Theo,

Here's one algorithm ... I doubt it is the best/most efficient out there; however, it works.

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

namespace ConsoleApplication1

{

    class Program

    {

        static void Main(string[] args)

        {

            List<string> alreadyHere = new List<string>(new string[] { "MA33I", "ZZ22C", "OO51A", "YU13O", "SX97Y" });

            Console.WriteLine("Alphanumeric generated code: \n\t" + getAlphaNumericCode(alreadyHere) + "\n");

            Console.ReadLine();

        }

        private static readonly string template = "__##_";

        static string getAlphaNumericCode(List<string> codesAlreadyInUse)

        {

            Random alphaRandomGen = new Random(DateTime.Now.Millisecond + DateTime.Now.Second);

            Random numericRandomGen = new Random(DateTime.Now.Millisecond + DateTime.Now.Second);

            string sANCode = string.Empty;

            do

            {

                for (int i = 0; i < template.Length; i++)

                {

                    int alphaChar = alphaRandomGen.Next(65, 91);

                    int numericChar = numericRandomGen.Next(48, 58);

                    if (template[i] == '_')

                        sANCode += Encoding.ASCII.GetString(new byte[] { (byte)alphaChar });

                    else

                        sANCode += Encoding.ASCII.GetString(new byte[] { (byte)numericChar });

                }

            } while (codesAlreadyInUse.Contains(sANCode));

            return sANCode;

        }

    }

}

Carl