C#

private void cmdSearch_Click(object sender, System.EventArgs e)
{
    if(txtSearch.Text == "")
    {
        MessageBox.Show("Please enter a value to search on");
    }
    else
    {

    }
}

private void txtSearch_KeyPress(object sender, System.Windows.Forms.KeyPressEventArgs e)
{
    if(e.KeyChar == 13)
    {
        cmdSearch_Click(sender, e);
    }
}

protected override void OnLoad(EventArgs e)
{
  myButton.Click += new EventHandler(click_a);
  myButton.Click += new EventHandler(click_b);
}
 
private void click_a(object sender, EventArgs e)
{
  MessageBox.Show("In click_a");
} 
 
private void click_b(object sender, EventArgs e)
{
  MessageBox.Show("In click_b");
}