using System;

using System.Linq;

​

public class Program

{

    public static void Main()

    {

        var rangemax = 200;

        var traceids = Enumerable.Range(0, rangemax).Select(a => Util.GetTraceId()).ToList();

        var distraceids = traceids.Distinct();

        var traceids2 = Enumerable.Range(0, rangemax).Select(a => Util.GetTraceId2()).ToList();

        var distraceids2 = traceids2.Distinct();

        //traceids2.ForEach(a => Console.WriteLine(a));

        Console.WriteLine("total:{0}, distinct:{1}", rangemax, distraceids.Count());

        Console.WriteLine("total:{0}, distinct:{1}", rangemax, distraceids2.Count());

        Console.ReadLine();

    }

​

    public static class Util

    {

        public static string GetTraceId()

        {

            string regionCode = "EU".Substring(0, 1);

            int randomNum = (new Random().Next(1, Int32.MaxValue));

            string uniqueTraceId = string.Concat(randomNum.ToString(), DateTime.Now.ToString("yyyyMMddHHmmss"));

            return string.Concat("CVRTT", regionCode, uniqueTraceId.PadLeft(25, '0'));

        }

​

        public static string GetTraceId2()

        {

            string regionCode = "EU".Substring(0, 1);

            return string.Concat("CVRTT", regionCode, Guid.NewGuid().ToString());

        }

    }

}