C#

using System;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Windows.Forms;

class MainForm : Form {

	class Card {
		public int Type;
		public Rectangle Position;
		public Bitmap Image;

		public Card(int Type, Rectangle Position) {
			this.Type = Type;
			switch (Type) {
				case 1:
					Image = new Bitmap("1.png");
					break;
				case 2:
					Image = new Bitmap("2.png");
					break;
				case 3:
					Image = new Bitmap("3.png");
					break;
				case 4:
					Image = new Bitmap("4.png");
					break; }
			this.Position = Position; } }

	Card RedCard = new Card(1, new Rectangle(0, 32, 32, 32));
	Card BlueCard = new Card(2, new Rectangle(0, 64, 32, 32));
	Card GreenCard = new Card(3, new Rectangle(0, 96, 32, 32));
	Card YellowCard = new Card(4, new Rectangle(0, 128, 32, 32));
	Card RedCard2 = new Card(1, new Rectangle(0, 160, 32, 32));

	int IsTaken = 0, OffsetX = 0, OffsetY = 0;
	PictureBox Table = new PictureBox();

	void DrawTable(object sender, PaintEventArgs e) {
		Color FirstColor = Color.FromArgb(46, 135, 46);
		e.Graphics.FillRectangle(new SolidBrush(FirstColor), 0, 0, 400, 400); }
		
// So far everything looks OK, but the next method feels wrong, because I have to call e.Graphics.DrawImage for each object of the class 'Card'. Is it possible to do something like: for each object of 'Card' { e.Graphics.DrawImage(objectName.Image, objectName.Position) } ?

	void DrawCards(object sender, System.Windows.Forms.PaintEventArgs e) {
		e.Graphics.InterpolationMode = InterpolationMode.NearestNeighbor;
		e.Graphics.PixelOffsetMode = PixelOffsetMode.Half;
		e.Graphics.DrawImage(RedCard.Image, RedCard.Position);
		e.Graphics.DrawImage(BlueCard.Image, BlueCard.Position);
		e.Graphics.DrawImage(GreenCard.Image, GreenCard.Position);
		e.Graphics.DrawImage(YellowCard.Image, YellowCard.Position);
		e.Graphics.DrawImage(RedCard2.Image, RedCard2.Position); }

// Can I simplify this somehow?
		
	int IsCursorOverCard(int X, int Y) {
		if ((X > RedCard.Position.Left) && (X <= RedCard.Position.Right) && (Y > RedCard.Position.Top) && (Y <= RedCard.Position.Bottom))
			return 1;
		else if ((X > BlueCard.Position.Left) && (X <= BlueCard.Position.Right) && (Y > BlueCard.Position.Top) && (Y <= BlueCard.Position.Bottom))
			return 2;
		else if ((X > GreenCard.Position.Left) && (X <= GreenCard.Position.Right) && (Y > GreenCard.Position.Top) && (Y <= GreenCard.Position.Bottom))
			return 3;
		else if ((X > YellowCard.Position.Left) && (X <= YellowCard.Position.Right) && (Y > YellowCard.Position.Top) && (Y <= YellowCard.Position.Bottom))
			return 4;
		else if ((X > RedCard2.Position.Left) && (X <= RedCard2.Position.Right) && (Y > RedCard2.Position.Top) && (Y <= RedCard2.Position.Bottom))
			return 5;
		else
			return 0; }

// I need redrawing method just to put taken card on top of other cards. But do I really need one method for each object? This looks wrong.
		
	void RedrawRedCard(object sender, System.Windows.Forms.PaintEventArgs e) {
		e.Graphics.InterpolationMode = InterpolationMode.NearestNeighbor;
		e.Graphics.PixelOffsetMode = PixelOffsetMode.Half;
		e.Graphics.DrawImage(RedCard.Image, RedCard.Position); }

	void RedrawBlueCard(object sender, System.Windows.Forms.PaintEventArgs e) {
		e.Graphics.InterpolationMode = InterpolationMode.NearestNeighbor;
		e.Graphics.PixelOffsetMode = PixelOffsetMode.Half;
		e.Graphics.DrawImage(BlueCard.Image, BlueCard.Position); }

	void RedrawGreenCard(object sender, System.Windows.Forms.PaintEventArgs e) {
		e.Graphics.InterpolationMode = InterpolationMode.NearestNeighbor;
		e.Graphics.PixelOffsetMode = PixelOffsetMode.Half;
		e.Graphics.DrawImage(GreenCard.Image, GreenCard.Position); }

	void RedrawYellowCard(object sender, System.Windows.Forms.PaintEventArgs e) {
		e.Graphics.InterpolationMode = InterpolationMode.NearestNeighbor;
		e.Graphics.PixelOffsetMode = PixelOffsetMode.Half;
		e.Graphics.DrawImage(YellowCard.Image, YellowCard.Position); }

	void RedrawRedCard2(object sender, System.Windows.Forms.PaintEventArgs e) {
		e.Graphics.InterpolationMode = InterpolationMode.NearestNeighbor;
		e.Graphics.PixelOffsetMode = PixelOffsetMode.Half;
		e.Graphics.DrawImage(RedCard2.Image, RedCard2.Position); }

// Can I simplify this along with IsCursorOverCard method?
		
	void TakeCard(object sender, MouseEventArgs e) {
		switch (IsCursorOverCard(e.X, e.Y)) {
			case 1:
				this.Table.Paint += new PaintEventHandler(this.RedrawRedCard);
				IsTaken = 1;
				OffsetX = RedCard.Position.X - e.X;
				OffsetY = RedCard.Position.Y - e.Y;
				break;
			case 2:
				this.Table.Paint += new PaintEventHandler(this.RedrawBlueCard);
				IsTaken = 2;
				OffsetX = BlueCard.Position.X - e.X;
				OffsetY = BlueCard.Position.Y - e.Y;
				break;
			case 3:
				this.Table.Paint += new PaintEventHandler(this.RedrawGreenCard);
				IsTaken = 3;
				OffsetX = GreenCard.Position.X - e.X;
				OffsetY = GreenCard.Position.Y - e.Y;
				break;
			case 4:
				this.Table.Paint += new PaintEventHandler(this.RedrawYellowCard);
				IsTaken = 4;
				OffsetX = YellowCard.Position.X - e.X;
				OffsetY = YellowCard.Position.Y - e.Y;
				break;
			case 5:
				this.Table.Paint += new PaintEventHandler(this.RedrawRedCard2);
				IsTaken = 5;
				OffsetX = RedCard2.Position.X - e.X;
				OffsetY = RedCard2.Position.Y - e.Y;
				break; } }

// Same here.
				
	void MoveCard(object sender, MouseEventArgs e) {
		switch (IsTaken) {
			case 0:
				if (IsCursorOverCard(e.X, e.Y) == 0)
					Table.Cursor = Cursors.Default;
				else
					Table.Cursor = Cursors.Hand;
				break;
			case 1:
				RedCard.Position.X = e.X + OffsetX;
				RedCard.Position.Y = e.Y + OffsetY;
				Table.Invalidate();
				break;
			case 2:
				BlueCard.Position.X = e.X + OffsetX;
				BlueCard.Position.Y = e.Y + OffsetY;
				Table.Invalidate();
				break;
			case 3:
				GreenCard.Position.X = e.X + OffsetX;
				GreenCard.Position.Y = e.Y + OffsetY;
				Table.Invalidate();
				break;
			case 4:
				YellowCard.Position.X = e.X + OffsetX;
				YellowCard.Position.Y = e.Y + OffsetY;
				Table.Invalidate();
				break;
			case 5:
				RedCard2.Position.X = e.X + OffsetX;
				RedCard2.Position.Y = e.Y + OffsetY;
				Table.Invalidate();
				break;	} }

// The rest is OK :-)
				
	void PutCard(object sender, MouseEventArgs e) {
		IsTaken = 0; }

	MainForm() {
		this.SuspendLayout();
		this.Width = 1024;
		this.Height = 768;
		this.Controls.Add(this.Table);
		this.Table.Location = new Point(0, 0);
		this.Table.Size = new Size(400, 400);
		this.Table.Paint += new PaintEventHandler(this.DrawTable);
		this.Table.Paint += new PaintEventHandler(this.DrawCards);
		this.Table.MouseDown += new MouseEventHandler(this.TakeCard);
		this.Table.MouseMove += new MouseEventHandler(this.MoveCard);
		this.Table.MouseUp += new MouseEventHandler(this.PutCard);
		this.ResumeLayout(); }

	static void Main() {
		Application.Run(new MainForm()); } }

WebClient webClient = new WebClient();
         
   a = "http://www.borsaitaliana.it/borsa/obbligazioni/mot/obbligazioni-in-euro/dati-completi.html?isin=DE000UB5WF78&lang=it";
         
   string page = webClient.DownloadString(a);

waveSource_DataAvailable

WaveIn waveSource;

waveSource = new WaveIn(this.Handle);

waveSource.DataAvailable += new EventHandler<WaveInEventArgs>(waveSource_DataAvailable);

void waveSource_DataAvailable(object sender, WaveInEventArgs e)
        {
            portReceived.Write(e.Buffer, 0, e.BytesRecorded); // send the voice from mic to the modem
        }

public class PipeSection
{
    public PipeSection(double radius)
    {
        this.Radius = radius;
    }

    public double Radius { get; set; }


    public double Calculate(double Frequency)
    {
        return Frequency * this.Radius;
    }

}

CancellationTokenSource ctr = new CancellationTokenSource();
       List<PipeSection> wn = new List<PipeSection>();

       public MainWindow()
       {
           InitializeComponent();

           PipeSection[] input = { new PipeSection(5), new PipeSection(6), new PipeSection(7) };

           wn.AddRange(input);

           //Calcualte at the frequencies 0,100,2000,3000
           var FreqData = new double[] { 0, 100, 2000, 3000 }.ToObservable<double>();

           FreqData
               //Off the ui thread
               .ObserveOn(Scheduler.Default)
               //Run each thread seperatly
               .SelectMany(x => Task.Run<double>(() => DoCalcualtions(x,wn), ctr.Token))
               //Back to the UI thread
               .ObserveOnDispatcher()
               //Subscribe and start the calcualtions
               .Subscribe(args => {
                                   //Update the progressbar when a thread is completed
                                   pgbProgress.Value += 1;
                                   //Tell me what thread is completed
                                   txtText.Text += Environment.NewLine + args.ToString();
                                   },
                           () => {
                                   //All done, here I could do sorting etc.
                                   txtText.Text += Environment.NewLine + "All done";
                                 }
                           );
       }

       private double DoCalcualtions(double Freq, List<PipeSection> input)
       {
           double result=1;
           for (int i = 0; i < input.Count(); i++)
               result *= input[i].Calculate(Freq);

           return result;
       }