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

namespace DEMO
{
    class Darrenstring
    {
        public class Matchpattern:Darrenstring
        {
            private string text;
            private string pattern;
            private int index;
            public bool ismatch;
            public Matchpattern(string Text, string Pattern)
            {
                text = Text;
                pattern = Pattern;
                Match a = Regex.Match(text,pattern);
                index=a.Index;
                ismatch = a.Success;
            }
            public int Index()
            {
                return index;
            }
            public string Before()
            {
                if (ismatch)
                {
                    return (text.Substring(0, index));
                }
                else return null;
            }
            public string After()
            {
                if (ismatch)
                {
                    return (text.Substring(index + pattern.Length, text.Length - pattern.Length-index));
                }
                else return null;
            }
        }
    }
}

 private void Confirm_Click(object sender, EventArgs e)
        {
            Darrenstring.Matchpattern A = new Darrenstring.Matchpattern(Source.Text, Terminal.Text);
            //Terminal.Text = Convert.ToString(A.Index());
            before1.Text = A.Before();
            After.Text = A.After();
            IsMatched.Checked = A.ismatch;            
        }