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Thursday, September 2, 2010

How to use back references to match the patterns?

I have provided a sample example of how to retrieve matched data from a text file using backreferences. This tutorial will help us in understanding how to create a regular expression for matching the repeating patterns from a source.I will explain in the video tutorial about how to match repeating letters and how to match repeating words from a given source. We will also see how to construct a regular expression for the above scenarios.After we do that we will see how to extract matched data from the source and use it for our purpose.

Video tutorial part - 1

Video Tutorial Part - 2

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Configuration;
using System.IO;
using System.Threading;
using System.Security.Permissions;
using System.Text.RegularExpressions;
namespace Example1
    class Program

        static void Main(string[] args)
            string SampleText = CreateString();

        static string CreateString()
            FileStream fs = new FileStream(@"C:\My stuff\Work Stuff\Blog\Test\SampleText.txt", FileMode.Open);

            StreamReader sr = new StreamReader(fs);
            string s = sr.ReadToEnd();

            return s;



        static void DisplayMatches(string s)
            Regex r;
            Match m;

            for (m = r.Match(s); m.Success; m = m.NextMatch())
                Console.WriteLine("Found repeating words  at "
                + m.Groups[1].Index + " And the macth is " + m.Groups[1].Value);


Sameer Shaik

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