using System;

using System.Text.RegularExpressions;

public class Program

{

    public void Main()

    {

        string[] guids = {

            "0C885DD3-7DD9-484B-9B20-3E6552BCA144", 

            "{0C885DD3-7DD9-484B-9B20-3E6552BCA144}",

            "0C885DD37DD9484B9B203E6552BCA144",

            "{0C885DD3-7DD9-484B-9B20-1E6552BCA144}",

            "0C885DD3-7DD9484B9B203E6552BCA144", 

            "0C885DD37DD9484B9B203E6552BCA14"

            };

        foreach(var guid in guids)

            TestGuid(guid);

    }

​

    public void TestGuid(string guid)

    {

        Console.WriteLine(

            String.Format("{0} : {1}, {2}", 

                          guid, 

                          guid.IsGuid(), 

                          guid.IsGuidRegEx()));

    }

}

​

public static class StringHelper

{

    public static bool IsGuid(this string guid)

    {

        Guid newGuid;

        return Guid.TryParse(guid, out newGuid);

    }

    public static bool IsGuidRegEx(this string guid)

    {

        if (guid != null)

        {

            Regex guidRegEx = 

                new Regex(@"^[{]?[0-9a-fA-F]{8}[-]?([0-9a-fA-F]{4}[-]?){3}[0-9a-fA-F]{12}[}]?$");

            return guidRegEx.IsMatch(guid);

        }

        return false;

    }

}

​