C#

<br />
using System.Runtime.InteropServices;<br />
<br />
...<br />
<br />
public class InternetConnection<br />
{<br />
	[DllImport("wininet.dll")]<br />
	public static extern bool InternetGetConnectedStateEx(out int lpdwFlags, byte[] szConn, int iConnSize, int dwReserved);<br />
<br />
	/// <summary><br />
	/// Status da conexão<br />
	/// </summary><br />
	public enum Status: int<br />
	{<br />
		/// <summary><br />
		/// Local system uses a modem to connect to the Internet.<br />
		/// </summary><br />
		INTERNET_CONNECTION_MODEM = 1,<br />
		/// <summary><br />
		/// Local system uses a local area network to connect to the Internet.<br />
		/// </summary><br />
        INTERNET_CONNECTION_LAN = 2,<br />
		/// <summary><br />
		/// Local system uses a proxy server to connect to the Internet.<br />
		/// </summary><br />
        INTERNET_CONNECTION_PROXY = 4,<br />
		/// <summary><br />
		/// Local system has RAS installed.<br />
		/// </summary><br />
        INTERNET_RAS_INSTALLED = 16,<br />
		/// <summary><br />
		/// Local system is in offline mode.<br />
		/// </summary><br />
        INTERNET_CONNECTION_OFFLINE = 32,<br />
		/// <summary><br />
		/// Local system has a valid connection to the Internet, but it might or might not be currently connected.<br />
		/// </summary><br />
        INTERNET_CONNECTION_CONFIGURED = 64<br />
	}<br />
<br />
	/// <summary><br />
	/// Returns true if connected<br />
	/// </summary><br />
	public static bool Connected<br />
	{<br />
		get {<br />
			bool bConn = false;<br />
			int flags = 0;<br />
			byte [] cName = new byte[512];<br />
			if(InternetGetConnectedStateEx(out flags, cName, 512, 0)) <br />
			{<br />
				bConn = true;<br />
			}<br />
			return bConn;<br />
		}<br />
	}<br />
				<br />
	public InternetConnection()<br />
	{<br />
	}<br />
}<br />
<br />
...<br />
<br />
InternetConnection inet = new InternetConnection();<br />
if(inet.Connected)<br />
{<br />
...<br />
}<br />
else<br />
{<br />
// not connected<br />
}<br />

private void pictureBox_Paint(object sender, PaintEventArgs e)
{
   e.Graphics.DrawImage(mybmp, position);  //put your drawing code here
}

private void pictureBox_Paint(object sender, PaintEventArgs e)
{
   if (mybmp != null)
   {
      e.Graphics.DrawImage(mybmp, position); //put your drawing code here
   }
}

private Bitmap mybmp=null;
private Rectangle position;  //non-reference types cannot be set to null

/// <summary>
///    The method to check whether the string is a numeral.
/// </summary>
public static bool IsNumber(string strNumber)
{
    Regex objNotNumberPattern=new Regex("[^0-9.-]");
    Regex objTwoDotPattern=new Regex("[0-9]*[.][0-9]*[.][0-9]*");
    Regex objTwoMinusPattern=new Regex("[0-9]*[-][0-9]*[-][0-9]*");
    String strValidRealPattern="^([-]|[.]|[-.]|[0-9])[0-9]*[.]*[0-9]+$";
    String strValidIntegerPattern="^([-]|[0-9])[0-9]*$";
    Regex objNumberPattern =new Regex("(" + strValidRealPattern +")|(" + strValidIntegerPattern + ")");
    return !objNotNumberPattern.IsMatch(strNumber) &&
        !objTwoDotPattern.IsMatch(strNumber) &&
        !objTwoMinusPattern.IsMatch(strNumber) &&
        objNumberPattern.IsMatch(strNumber);
}