Read File into Byte Array

string filePath = @"C:\test.doc";
byte[] byteArray = File.ReadAllBytes( filePath );

C# Convert String to Byte Array

string s = "Test String";
byte[] byteArray = Encoding.ASCII.GetBytes( s );

Pass parameters to the timer in C#

These days I am using C# to develop the timer component running as a windows service, which runs automatically in a specific interval.

In C#, there are 3 kinds of timer type definitions:

1. System.Windows.Forms.Timer
2. System.Threading.Timer
3. System.Timers.Timer

In my project, I choose to use the third one: System.Timers.Timer
Here is the sample usage of this kind of timer:

System.Timers.Timer timer = new System.Timers.Timer();
timer. Interval = 10000; // set the interval as 10000 ms
timer.Elapsed += new System.Timers.ElapsedEventHandler(this.timer_Elapsed); // set the event to execute
timer.AutoReset = true; // false: only execute once
timer.Enabled = true; // to decide if execute the event of timer specified
…
public void timer_Elapsed(object sender, EventArgs e)
{
…
}
From the above sample, we know it is quite easy to use it.

Next, I have a problem if I need pass some parameters to be used in the timer event defined above: timer_Elapsed(…). The two input parameters of this event interface are fixed, you can’t add more in.

There is a tricky to achieve it. Since we can’t add more input parameters in this event, we can set the parameters into the unused property of that sender object. This way is simple, but not good.

After researching, i find a better way to deal with it: creating a new timer to extend the system timer , and then defining the additional parameters inside this new timer.

Here are the sample codes:

// define a class to extend the timer,
// then define those additional parameters to be used in the event.
// for example: add one more parameter: param1.
namespace XXX
{
public class TaskTimer : Timer{
private string param1;

public string Param1
{
get
{
return param1;
}
set
{
param1= value;
}
}

public TaskTimer() : base()
{
}
}
}
// usage of this timer
using XXX;
…
TaskTimer timer = new TaskTimer();
timer.Interval = 10000;
…

// the event definition
public void timer_Elapsed(object sender, EventArgs e)
{
String param1 = (TaskTimer) sender).Param1;…
}

A simple Binary Search Tree written in C#

node search (node, key) {
       if node is null then return null;
       
       if node.key = key then
          return node
          
       if key < node then
          return search (node.left, key);
       else
          return search (node.right, key);

==============================================

// Create a new binary tree
bt = new TBinarySTree();

// Insert data
bt.insert ("Canis Minoris", 5.37);
bt.insert ("Gamma Cancri", 4.66);
bt.insert ("Phi Centauri", 3.83);
bt.insert ("Kappa Tauri", 4.21);
 
// Retrieve data  
TTreeNode symbol = bt.findSymbol ("Phi Centauri");
if (symbol != null)
   Console.WriteLine ("Star {1} has magnitude = {0}", symbol.name, symbol.value); 

string reversing algorithms

            charArray1 = textBox1.Text.ToCharArray();
            Array.Reverse(charArray1);
            label1.Text = new string(charArray1);

[C#] TcpListenser

[C#] 

using System;

using System.IO;

using System.Net;

using System.Net.Sockets;

using System.Text;

class MyTcpListener

{

  public static void Main()

  {    

    try

    {

      // Set the TcpListener on port 13000.

      Int32 port = 13000;

      IPAddress localAddr = IPAddress.Parse("127.0.0.1");

      // TcpListener server = new TcpListener(port);

      TcpListener server = new TcpListener(localAddr, port);

      // Start listening for client requests.

      server.Start();

      // Buffer for reading data

      Byte[] bytes = new Byte[256];

      String data = null;

      // Enter the listening loop.

      while(true) 

      {

        Console.Write("Waiting for a connection... ");

        // Perform a blocking call to accept requests.

        // You could also user server.AcceptSocket() here.

        TcpClient client = server.AcceptTcpClient();            

        Console.WriteLine("Connected!");

        data = null;

        // Get a stream object for reading and writing

        NetworkStream stream = client.GetStream();

        int i;

        // Loop to receive all the data sent by the client.

        while((i = stream.Read(bytes, 0, bytes.Length))!=0) 

        {   

          // Translate data bytes to a ASCII string.

          data = System.Text.Encoding.ASCII.GetString(bytes, 0, i);

          Console.WriteLine(String.Format("Received: {0}", data));

          // Process the data sent by the client.

          data = data.ToUpper();

          byte[] msg = System.Text.Encoding.ASCII.GetBytes(data);

          // Send back a response.

          stream.Write(msg, 0, msg.Length);

          Console.WriteLine(String.Format("Sent: {0}", data));            

        }

        // Shutdown and end connection

        client.Close();

      }

    }

    catch(SocketException e)

    {

      Console.WriteLine("SocketException: {0}", e);

    }

    Console.WriteLine("\nHit enter to continue...");

    Console.Read();

  }   

}

How to encrypt and decrypt a file by using Visual C#

using System;
using System.IO;
using System.Security;
using System.Security.Cryptography;
using System.Runtime.InteropServices;
using System.Text;

namespace CSEncryptDecrypt
{
   class Class1
   {
      //  Call this function to remove the key from memory after use for security
      [System.Runtime.InteropServices.DllImport("KERNEL32.DLL", EntryPoint="RtlZeroMemory")]
      public static extern bool ZeroMemory(IntPtr Destination, int Length);
  
      // Function to Generate a 64 bits Key.
      static string GenerateKey() 
      {
         // Create an instance of Symetric Algorithm. Key and IV is generated automatically.
         DESCryptoServiceProvider desCrypto =(DESCryptoServiceProvider)DESCryptoServiceProvider.Create();

         // Use the Automatically generated key for Encryption. 
         return ASCIIEncoding.ASCII.GetString(desCrypto.Key);
      }

      static void EncryptFile(string sInputFilename,
         string sOutputFilename, 
         string sKey) 
      {
         FileStream fsInput = new FileStream(sInputFilename, 
            FileMode.Open, 
            FileAccess.Read);

         FileStream fsEncrypted = new FileStream(sOutputFilename, 
            FileMode.Create, 
            FileAccess.Write);
         DESCryptoServiceProvider DES = new DESCryptoServiceProvider();
         DES.Key = ASCIIEncoding.ASCII.GetBytes(sKey);
         DES.IV = ASCIIEncoding.ASCII.GetBytes(sKey);
         ICryptoTransform desencrypt = DES.CreateEncryptor();
         CryptoStream cryptostream = new CryptoStream(fsEncrypted, 
            desencrypt, 
            CryptoStreamMode.Write); 

         byte[] bytearrayinput = new byte[fsInput.Length];
         fsInput.Read(bytearrayinput, 0, bytearrayinput.Length);
         cryptostream.Write(bytearrayinput, 0, bytearrayinput.Length);
         cryptostream.Close();
         fsInput.Close();
         fsEncrypted.Close();
      }

      static void DecryptFile(string sInputFilename, 
         string sOutputFilename,
         string sKey)
      {
         DESCryptoServiceProvider DES = new DESCryptoServiceProvider();
         //A 64 bit key and IV is required for this provider.
         //Set secret key For DES algorithm.
         DES.Key = ASCIIEncoding.ASCII.GetBytes(sKey);
         //Set initialization vector.
         DES.IV = ASCIIEncoding.ASCII.GetBytes(sKey);

         //Create a file stream to read the encrypted file back.
         FileStream fsread = new FileStream(sInputFilename, 
            FileMode.Open, 
            FileAccess.Read);
         //Create a DES decryptor from the DES instance.
         ICryptoTransform desdecrypt = DES.CreateDecryptor();
         //Create crypto stream set to read and do a 
         //DES decryption transform on incoming bytes.
         CryptoStream cryptostreamDecr = new CryptoStream(fsread, 
            desdecrypt,
            CryptoStreamMode.Read);
         //Print the contents of the decrypted file.
         StreamWriter fsDecrypted = new StreamWriter(sOutputFilename);
         fsDecrypted.Write(new StreamReader(cryptostreamDecr).ReadToEnd());
         fsDecrypted.Flush();
         fsDecrypted.Close();
      } 

      static void Main()
      {
         // Must be 64 bits, 8 bytes.
         // Distribute this key to the user who will decrypt this file.
         string sSecretKey;
         
         // Get the Key for the file to Encrypt.
         sSecretKey = GenerateKey();

         // For additional security Pin the key.
         GCHandle gch = GCHandle.Alloc( sSecretKey,GCHandleType.Pinned );
         
         // Encrypt the file.        
         EncryptFile(@"C:\MyData.txt", 
            @"C:\Encrypted.txt", 
            sSecretKey);

         // Decrypt the file.
         DecryptFile(@"C:\Encrypted.txt", 
            @"C:\Decrypted.txt", 
            sSecretKey);

         // Remove the Key from memory. 
         ZeroMemory(gch.AddrOfPinnedObject(), sSecretKey.Length * 2);
         gch.Free();
      }
   }
}

Converting a bitmap to a byte array

// Bitmap bytes have to be created via a direct memory copy of the bitmap
private byte[] BmpToBytes_MemStream (Bitmap bmp)
{
 MemoryStream ms = new MemoryStream();
 // Save to memory using the Jpeg format
 bmp.Save (ms, ImageFormat.Jpeg);
 
 // read to end
 byte[] bmpBytes = ms.GetBuffer();
 bmp.Dispose();
 ms.Close();

 return bmpBytes;
}

 //Bitmap bytes have to be created using Image.Save()
private Image BytesToImg (byte[] bmpBytes)
{
 MemoryStream ms = new MemoryStream(bmpBytes);
 Image img = Image.FromStream(ms);
 // Do NOT close the stream!
 
 return img;
}