How to: Determine which Web Server Control Raised an Event
When an event handler is called, you can determine which control caused the event.
To determine which control caused the event
In the event handler, declare a variable whose type matches the control that raised the event.
Assign the sender argument of the event handler to the variable, casting it to the appropriate type.
The following example shows the handler for a-control click event that is called by several different buttons. The handler displays information about which button was clicked.
Private Sub Button1_Click(ByVal sender As System.Object, _ ByVal e As System.EventArgs) _ Handles Button1.Click, Button2.Click, Button3.Click Dim b As Button b = CType(sender, Button) Select Case b.ID Case "Button1" Label1.Text = "You clicked the first button" Case "Button2" Label1.Text = "You clicked the second button" Case "Button3" Label1.Text = "You clicked the third button" End Select End Sub