using System;

using System.Text.RegularExpressions;

​

public class Program

{

    public static void Main()

    {

        string regexPattern = @"hello";

        Regex regex = new Regex(regexPattern);

        string inputString = "hello world! hello again!";

        MatchCollection matches = regex.Matches(inputString);

        foreach (Match match in matches)

        {

            Console.WriteLine("Match found at index {0} with length {1}", match.Index, match.Length);

        }

    }

}