Pass number into event

Question

I would like to ask you for help. I dynamically creating a lot of textboxes and I am using LostFocus event (C#).

Is it possible to create event with passing of number ID of textbox?

Something like

(object sender,EventArgs,int ID)

and

tbx.LostFocus+= EventHandler(MySubFunction(3)?? --3 is my ID of textbox

Thank you for help, I am lost in this I do not know how to add any number to EventHandler call

Answer 1

If you are using winforms you can use the Tag property to distinguish between different controls:

var textbox = new TextBox();
textbox.Tag = 42;
textbox.LostFocus += TextboxLostFocus;

...
void TextboxLostFocus(object sender, EventArgs e){
   if(sender is TextBox txtBox && txtBox.Tag is int textboxNum){
      // use textboxNum
   }
}

Or you can use lambdas to register your event with a built in number:

var textbox = new TextBox();
textbox.LostFocus += (o, e) => TextboxLostFocus(42);

...
void TextboxLostFocus(int textboxNum){
      // use textboxNum
}