Question

I have to write a program to check if any random string is present in a file. And i did so.. But now i was asked to use sockets.send and receive method. I’ve created a connection and written the code till here.. How do i proceed further? I’m not able to figure it out.. The first program is my try at server side program. And the second is my actual program to search for a string from the file. Could someone help me with the code on how to use the sockets in my actual program? Thanks alot.. 🙂

class Program
{
    static void Main(string[] args)
    {
        TcpListener serversocket = new TcpListener(8888);
        int requestcount = 0;
        TcpClient clientsocket = default(TcpClient);
        serversocket.Start();
        Console.WriteLine(">> Server Started");
        clientsocket = serversocket.AcceptTcpClient();
        Console.WriteLine("Accept Connection From Client");
        requestcount = 0;


        while ((true))
        {
            try
            {
                requestcount = requestcount + 1;
                NetworkStream networkstream = clientsocket.GetStream();
                byte[] bytesFrom = new byte[10025];
                networkstream.Read(bytesFrom, 0, (int)clientsocket.ReceiveBufferSize);
                string dataFromClient = System.Text.Encoding.ASCII.GetString(bytesFrom);
                dataFromClient = dataFromClient.Substring(0, dataFromClient.IndexOf("$"));
                Console.WriteLine(" >> Data from client - " + dataFromClient);
                string serverResponse = "Server response " + Convert.ToString(requestcount);
                Byte[] sendBytes = Encoding.ASCII.GetBytes(serverResponse);
                networkstream.Write(sendBytes, 0, sendBytes.Length);
                networkstream.Flush();
                Console.WriteLine(" >> " + serverResponse);
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.ToString());
            }
        }
        clientsocket.Close();
        serversocket.Stop();
        Console.WriteLine(" >> exit");
        Console.ReadLine();
       }
  } 

This is the program i want to use in the above program.

class Program
{

    static void Main(string[] args)
    {
        if (File.Exists("C://myfile2.txt"))
        {
            var text = File.ReadAllText("C://myfile2.txt");


            foreach (var word in new[] { "and", "so", "not", "c", "to", "by", "has", "do", "behavior", "dance", "france", "ok","thast", "please","hello","system","possible","impossible","absolutely","sachin","bradman","schumacher","http","console","application" })
            {
                var w = word;

                new Thread(() => Console.WriteLine("{0}: {1}", w, text.Contains(w) ? "Present" : "Not Present")).Start();
            }

        }
        else
            Console.WriteLine("File Does not exist");
        Console.ReadLine();
    }

}

Answer 1

Here is a quick and dirty idea that I wrote without an IDE (—I haven’t tested it— Edit just tested it with netcat, and it works fine):

• Note it uses a regular expression. If the lookup table for words grows sufficiently large, you’d be better of storing the words in a HashSet<string> and splitting the input into words. You can then efficiently do a .IntersectWith to see whether any of the words are matched.

• Note that the socket’s constructor is deprecated (you are supposed to explicitely specify and IPAddress to bind to)

• Your original code doesn’t require matches to be separate words (candy matches both c and and). You might want to fix that

• The parts that were inefficient in the original ‘grep’ snippet:

  • ReadAllText (won’t scale for large files)
  • Doing multiple .Contains calls in a loop will be far less efficient than using a (precompiled) regular expression
  • Why on earth are threads being created there? This will literally only add runtime overhead and potentially lead to problems due to the unsynchronized access to Console.Out.

.

using System;
using System.IO;
using System.Text;
using System.Text.RegularExpressions;
using System.Net.Sockets;

class Program
{
    private static Regex _regex = new Regex("and|so|not|c|to|by|has|do|behavior|dance|france|ok|thast|please|hello|system|possible|impossible|absolutely|sachin|bradman|schumacher|http|console|application", RegexOptions.Compiled | RegexOptions.IgnoreCase | RegexOptions.CultureInvariant);

    static void Main(string[] args)
    {
        TcpListener serversocket = new TcpListener(8888);
        TcpClient clientsocket = default(TcpClient);
        serversocket.Start();
        Console.WriteLine(">> Server Started");
        clientsocket = serversocket.AcceptTcpClient();
        Console.WriteLine("Accept Connection From Client");

        try
        {
            using (var reader = new StreamReader(clientsocket.GetStream()))
            {
                string line;
                int lineNumber = 0;
                while (null != (line = reader.ReadLine()))
                {
                    lineNumber += 1;
                    foreach (Match match in _regex.Matches(line))
                    {
                        Console.WriteLine("Line {0} matches {1}", lineNumber, match.Value);
                    }
                }
            }
        }
        catch (Exception ex)
        {
            Console.Error.WriteLine(ex.ToString());
        }

        clientsocket.Close();
        serversocket.Stop();
        Console.WriteLine(" >> exit");
        Console.ReadLine();
    }
}