Question

using System;
using System.IO;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Text.RegularExpressions;

namespace RegExCs
{
    class Program
    {
        static void Main(string[] args)
        {
            string rawData;
            Regex filter = new Regex(@"(?<ip>([0-9]+\.){3}[0-9])"+@"(?<time>(\s[0-2][0-9]:[0-9][0-9]))");


            rawData=File.ReadAllText("Query list");

            MatchCollection theMatches = filter.Matches(rawData);

            foreach (Match theMatch in theMatches)
            {
                Console.WriteLine("ip: {0}\n",theMatch.Groups["ip"]);
                Console.WriteLine("time: {0}\n", theMatch.Groups["time"]);
            }


            Console.ReadKey();

        }
    }
}

“Query list” file:

Reply from 212.77.100.101 www.wp.pl time: 21:37
Reply from 111.41.130.55 www.cnn.com time: 05:33
Reply from 230.77.100.101 www.piting.com time: 04:12
Reply from 65.77.100.101 www.ha.org time: 12:55
Reply from 200.77.100.101 www.example.com time: 07:56

This program compiles and runs, but the empty console window is opened the whole time. Why?

Answer 1

Because nothing matches to the regexp

@"(?<ip>([0-9]+\.){3}[0-9])(?<time>(\s[0-2][0-9]:[0-9][0-9]))"

You just concatenate 2 strings, and the compound regex expects the string to be ip followed by time without anything else (even a space) between them.

You need to change it to

@"(?<ip>([0-9]+\.){3}[0-9]).*(?<time>(\s[0-2][0-9]:[0-9][0-9]))"
                           ^------- "anything" between first and second group