Why do form control event names change when code is copied from a different project?

Question

Scenario is:

• I have a button called X in project A

• One of the events for X is the following:

  private void X_KeyDown(object sender, KeyEventArgs e)
  {//if the user presses Ctrl + V 
      if (e.KeyCode == Keys.Control && e.KeyCode == Keys.V)
      {
        MessageBox.Show("hello");  
      }
  }
  

• I've now created a new poject B and added a button to a form and also called it X. I then copied the above code into Form1.cs.

Question: If I go to form B and select the button and then double click the KeyDown event it does not go to the code I copied in but creates the following. Why ?

private void X_KeyDown_1(object sender, KeyEventArgs e)
{

}

Answer 1

Because you have neglected to copy the actual event binding, which is declared in your Form1.Designer.cs file. Something like

X.Click += new System.KeyDownEventHandlerEtcEtc;

Because this is missing, the studio thinks you're trying to create a new event handler. But because the default name for that event handler it tacks on a _1.

To overcome this, you can set the Click event in the designer manually to the specified, copied event handler. Or indeed any event handler with a matching signature.

Another way to do this is to not copy the entire event handler, but only the logic - then create a new handler in your new Form, pasting the logic there.