using System;

using System.Text.RegularExpressions;

public class Program

{

    public static void Main()

    {

        var ser = new string[]{

            "attack.asc",

            "attack.desc",

            "actor.asc",

            "Actor.asc",

            "aTtack.asc",

            "xapplication.Asc",

            "application.desc",

            "aplication.desc",

            "ctor.asc"

        };

​

        foreach(var str in ser){

             Test(str);

        }

    }

    private static readonly Regex Pattern = new Regex(@"^(?i:attack|actor|application)\.(?i:asc|desc)$");

​

    public static void Test(string input)

    {

        Console.Write(input);

        if( Pattern.IsMatch(input))

            Console.Write("    match\n");

        else

            Console.Write("     no\n");

    }

}