C#

private btn1Click(object sender, EventArgs e){
   this.Hide();
   DataForm df = new DataForm();
   df.ShowDialog();
   
   //now show back your main form
   this.Show();
}

//Holds results from CustomerID validataion.
DataTable customerTable = new DataTable();

//Query the Database
using (MySql.Data.MySqlClient.MySqlConnection conn = new MySql.Data.MySqlClient.MySqlConnection("server=serverName;uid=userID;pwd=password;database=databaseName"))
{
    string validationQuery = "SELECT * FROM Table WHERE Contact_ID = '" + actNumber + "';";
    MySql.Data.MySqlClient.MySqlDataAdapter odda = new MySql.Data.MySqlClient.MySqlDataAdapter(validationQuery, conn);
    odda.Fill(customerTable);
}

public class DataChangedEventArgs : EventArgs
{
    private String _strArgVal = "";
    public DataChangedEventArgs(String Value)
    {
        _strArgVal = Value;
    }
}
public delegate void DataChangedEventHandler(object sender, DataChangedEventArgs e);
public class MyUserControlOne
{
    String DataString = String.Empty;
    private bool isEventWorking = false;
    public event DataChangedEventHandler DataChanged;
    public MyUserControlOne()
    {
        DataString = "";
        this.DataChanged += new DataChangedEventHandler(MyUserControlOne_DataChanged);
    }

    protected void MyUserControlOne_DataChanged(object sender, DataChangedEventArgs e)
    {
        isEventWorking = true;
    }
    protected virtual void OnDataChanged(DataChangedEventArgs e)
    {
        DataChanged(this, e);
    }
    public String SetData
    {
        set
        {
            if (value != DataString)
            {
                OnDataChanged(new DataChangedEventArgs("Event Fired !!!"));
            } DataString = value;
        }
    }
    public bool EventWorking
    {
        get { return isEventWorking; }
    }
}

static void Main(string[] args)
{
    MyUserControlOne o = new MyUserControlOne();
    o.SetData = "ABC";
    o.SetData = "ABCD";
    o.SetData = "ABCD";
    Console.WriteLine(o.EventWorking);
}

Arindam Tewary wrote:

protected virtual void OnDataChanged(DataChangedEventArgs e)
{
    DataChanged(this, e);
}

protected virtual void OnDataChanged(DataChangedEventArgs e)
   {
   EventHandler eh = DataChanged;
   if (eh != null)
      {
      eh(this, e);
      }
   }

protected virtual void OnDataChanged(DataChangedEventArgs e)
{
   if (DataChanged != null)
      DataChanged(this, e);

}

Arindam Tewary wrote:

if (value != DataString)
{
OnDataChanged(new DataChangedEventArgs("Event Fired !!!"));
} DataString = value;

private void FileComparerThread()
		{

			while (this.stopRequested != true)
			{

				for (int i = 0; i < Directory.GetFiles(this.dest).Length; i++)
				{
					string[] filePaths = Directory.GetFiles(this.dest, "*.txt");

					for (int j = 0; j < filePaths.Length; j++)
					{ // check if btnCancel has been pressed if so, end this thread.
						if (this.stopRequested != true)
						{
							// check if file names are not the same:
							if (filePaths[i].ToString() != filePaths[j].ToString())
							{
								bool comparedFiles = this.FileCompare(filePaths[i].ToString(), filePaths[j].ToString());

								// move 1 file if they are both the same to another directory
								if (comparedFiles)
									Directory.Move(filePaths[j], Path.Combine(this.dest2, Path.GetFileName(filePaths[j])));
							}
						}

					}
					
					if(filePaths.Length > 3)
						File.Move(filePaths[i], Path.Combine(this.dest, Path.GetFileName(filePaths[i])));
					
					Thread.Sleep(5000);
				}
			}
		}

if (this.stopRequested != true)
{
... some code...
}

if (stopRequested)
  return;