C#

protected override bool IsInputKey(Keys key)
{
   if (key.KeyCode == Keys.Up) return true;
   else if (key.KeyCode == Keys.Down) return true;
   else if (key.KeyCode == Keys.Left) return true;
   else if (key.KeyCode == Keys.Right) return true;
   else return base.IsInputKey(key);
}

<br />
protected override bool ProcessKeyPreview( ref System.Windows.Forms.Message mes )<br />
		{<br />
			Keys keyCode = (Keys)(int)mes.WParam & Keys.KeyCode; <br />
 <br />
			if((mes.Msg == WM_KEYDOWN || mes.Msg == WM_KEYUP) && keyCode == Keys.Down  ) <br />
			{<br />
				MessageBox.Show("Arrow handled");<br />
				return true;<br />
			}<br />
			else<br />
				return false;  <br />
<br />
		}<br />

<br />
Form1_Load()<br />
this.myControl.KeyDown += new KeyEventHandler(this.MyKeyDownEvent);<br />
<br />
<br />
...<br />
<br />
<br />
private void MyKeyDownEvent( object sender, KeyEventArgs e )<br />
{<br />
   if ( e.KeyCode == Keys.A )<br />
        MessageBox.SHow("Hey you typed an AS");<br />
}<br />

public delegate void LoadTreeViewHandler(System.Windows.Forms.TreeView tv);

// Syncronized class
[Synchronization()]
public class SampleSyncronized : ContextBoundObject
{
public void LoadTreeView( System.Windows.Forms.TreeView crossTV )
{
Invoke( new LoadTreeViewHandler(LoadTreeViewNow), new object[] { crossTV } );
}

private void LoadTreeViewNo (System.Windows.Forms.TreeView tv)
{
 // add tree node code here
}

public XPathNodeIterator SelectSorted(XmlNode node, XmlNamespaceManager namespacemanager)
{
	XPathNavigator nav = node.CreateNavigator();
	XPathExpression xpathExpr = nav.Compile("xpath_expression");
	xpathExpr.SetContext(namespacemanager);
 
	xpathExpr.AddSort("sort_expression", XmlSortOrder.Ascending, XmlCaseOrder.None, String.Empty, XmlDataType.Text);
 
	return nav.Select(xpathExpr);
}

 An expression representing the sort key. This can be a string or
an XPathExpression object. The result of this expression is converted
to a string, according to the XPath specification, for comparison. In
an XSLT stylesheet, if xsl:sort is used, but no select expression is
specified, then string(.) is used by default.

System.Web.HttpUtility.UrlDecode("Encoded%20String");

int[] i;  //declare an array of unknown size
i=new int[]{0,1,2,3,4,5}; //create an array from literals
i=GetArray(); //get an array from a function

using System.Collections;
...
array = new ArrayList();
 
// keep adding items to the ArrayList here.
 
int[] myArray = array.ToArray(typeof(int));