C#

[Flags]
public enum MyKeys : int
{
  Null	= 0,
  Up	= 0x01,
  Down	= 0x02,
  Left	= 0x04,
  Right	= 0x08
}

...
MyKeys keys = MyKeys.Up | MyKeys.Right;

if((keys&MyKeys.Right) == MyKeys.Right)
  MessageBox.Show("keys contains MyKeys.Right!");

0x01 = 0001
0x02 = 0010
0x04 = 0100
0x08 = 1000

using System;

class Test
{
    enum Days
    {
        Mon = 1,
        Tue = 2
    };

    [Flags]
    enum DaysFlag
    {
        Mon = 1,
        Tue = 2
    };

    static void Main()
    {
        int a = (int) (Days.Mon | Days.Tue);
        int b = (int)(DaysFlag.Mon | DaysFlag.Tue);

        return;
    }
}

merh wrote:

I have done like this but the result is wrong.

int i;
byte[] s ={ 10, 20 };
int result=0;
for (i = 0; i <= 1; i++)
  result += s[i];

public partial class Form1 : Form<br />
    {<br />
        int lastX;<br />
        int lastY;<br />
        bool reverse = false;<br />
        Pen pen = new Pen(Brushes.Red, 2);<br />
<br />
        public Form1()<br />
        {<br />
            InitializeComponent();<br />
            this.SetStyle(ControlStyles.AllPaintingInWmPaint | ControlStyles.UserPaint | ControlStyles.OptimizedDoubleBuffer, true);<br />
        }        <br />
<br />
        private void panel1_Paint(object sender, PaintEventArgs e)<br />
        {<br />
            this.timer1.Start();<br />
            this.panel1.Invalidate();<br />
        }<br />
<br />
        private void Paint(Graphics g,int x,int y)<br />
        {<br />
            g.Clear(Color.White);<br />
            g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighSpeed;<br />
            g.DrawEllipse(this.pen, new Rectangle(x, y, 100, 100));<br />
            this.panel1.Invalidate();<br />
        }<br />
<br />
        private void timer1_Tick(object sender, EventArgs e)<br />
        {<br />
            if (!this.reverse)<br />
            {<br />
                if ((this.lastX + 102) <= this.panel1.Width)<br />
                {<br />
                    this.lastX += 2;<br />
                }<br />
                else<br />
                {<br />
                    this.reverse = true;<br />
                }<br />
            }<br />
            else<br />
            {<br />
                if (this.lastX >= 0)<br />
                {<br />
                    this.lastX -= 2;<br />
                }<br />
                else<br />
                {<br />
                    this.reverse = false;<br />
                }<br />
            }<br />
            this.Paint(this.panel1.CreateGraphics(), this.lastX, this.lastY);<br />
        }        <br />
    }

private void panel1_Paint(object sender, PaintEventArgs e)
{
  this.Paint(e.Graphics, this.lastX, this.lastY);
}

int lastX;
int lastY;
bool reverse = false;
Pen pen = new Pen(Brushes.Red, 2);

public Form1()
{
  InitializeComponent();
  this.SetStyle(ControlStyles.AllPaintingInWmPaint | ControlStyles.UserPaint | ControlStyles.OptimizedDoubleBuffer, true);
  this.timer1.Start();
} 

private void panel1_Paint(object sender, PaintEventArgs e)
{
  this.Paint(e.Graphics, this.lastX, this.lastY);
}

private void Paint(Graphics g,int x,int y)
{
  g.Clear(Color.White);
  g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighSpeed;
  g.DrawEllipse(this.pen, new Rectangle(x, y, 100, 100));
  this.panel1.Invalidate();
}

private void timer1_Tick(object sender, EventArgs e)
{
  if (!this.reverse)
  {
    if ((this.lastX + 102) <= this.panel1.Width)
    {
      this.lastX += 2;
    }
    else
    {
      this.reverse = true;
    }
  }
  else
  {
    if (this.lastX >= 0)
    {
      this.lastX -= 2;
    }
    else
    {
      this.reverse = false;
    }
  }
  this.panel1.Invalidate();
}

public partial class Form1 : Form<br />
    {<br />
        int lastX; int lastY; <br />
        bool reverse = false; <br />
        Pen pen = new Pen(Brushes.Red, 2); <br />
        <br />
        public Form1() <br />
        { <br />
            InitializeComponent(); <br />
            this.SetStyle(ControlStyles.AllPaintingInWmPaint | ControlStyles.UserPaint | ControlStyles.OptimizedDoubleBuffer, true); this.timer1.Start();<br />
        } <br />
        <br />
        private void panel1_Paint(object sender, PaintEventArgs e) <br />
        { <br />
            this.Paint(e.Graphics, this.lastX, this.lastY);<br />
        }<br />
        <br />
        private void Paint(Graphics g, int x, int y) <br />
        { <br />
            g.Clear(Color.White); <br />
            g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighSpeed; <br />
            g.DrawEllipse(this.pen, new Rectangle(x, y, 100, 100)); <br />
            this.panel1.Invalidate(); <br />
        }<br />
        <br />
        private void timer1_Tick(object sender, EventArgs e) <br />
        { <br />
            if (!this.reverse)             <br />
            { <br />
                if ((this.lastX + 102) <= this.panel1.Width) <br />
                { <br />
                    this.lastX += 2;<br />
                } <br />
                else <br />
                { <br />
                    this.reverse = true;<br />
                } <br />
            } <br />
            else <br />
            { <br />
                if (this.lastX >= 0) <br />
                { <br />
                    this.lastX -= 2; <br />
                } <br />
                else <br />
                { <br />
                    this.reverse = false;<br />
                } <br />
            } this.panel1.Invalidate();<br />
        }<br />
    }