Regular Expresion Part : Regular Expression « Regular Expression « C# / CSharp Tutorial

1. C# / CSharp Tutorial
2. Regular Expression
3. Regular Expression

using System;
using System.Text;
using System.Text.RegularExpressions;

public class MainClass
{
    static void Main( string[] args ) {
        // Create regex to search for IP address pattern.
        string pattern = @"(?<part1>[01]?\d\d?|2[0-4]\d|25[0-5])\." +
                         @"(?<part2>[01]?\d\d?|2[0-4]\d|25[0-5])\." +
                         @"(?<part3>[01]?\d\d?|2[0-4]\d|25[0-5])\." +
                         @"(?<part4>[01]?\d\d?|2[0-4]\d|25[0-5])";
        Regex regex = new Regex( pattern );
        Match match = regex.Match( "192.1.1.122" );

        MatchEvaluator eval = new MatchEvaluator(IPReverse );
        Console.WriteLine( regex.Replace("192.1.1.122", eval) );
    }

    static string IPReverse( Match match ) {
        StringBuilder sb = new StringBuilder();
        sb.Append( match.Groups["part4"] + "." );
        sb.Append( match.Groups["part3"] + "." );
        sb.Append( match.Groups["part2"] + "." );
        sb.Append( match.Groups["part1"] );
        return sb.ToString();
    }
}

122.1.1.192