Method name expected c#

问题

I have an event handler, i would like to pass some parameters to the event

like this, that line trigger an error: method name expected

   p.Click += new System.EventHandler(P_Click(sender, new MyEventArgs { design = reader1["desig_prd"].ToString(), prix = (float)reader1["prix_prd"] }));

my P_Click event

public void P_Click(Object sender, EventArgs e)
    {
        var args = (MyEventArgs)e;
        string deignation = args.design;
        MessageBox.Show(deignation);
    }

and i have class MyEventArgs like this

class MyEventArgs : EventArgs
{
    public string design { get; set; }
    public float prix { get; set; }
}

Any help? Thanks in advance

回答1:

You can't pass arguments to your method when you subscribing an event handler.You should just specify the method name:

p.Click +=  new EventHandler(P_Click);

Or short notation:

p.Click +=  P_Click;

If you want to trigger this manually and pass some arguments then you should call your method with that arguments:

P_Click(this, new MyEventArgs { design = reader1["desig_prd"].ToString(), 
                                prix = (float)reader1["prix_prd"] 
                              });

But this is usually a bad practice, (triggering event handler methods manually).Instead use PerformClick method after subscribe your event handler and of course create another method for your arguments, and call that method from P_Click:

p.PerformClick();

回答2:

Change it to this

 p.Click += new System.EventHandler(P_Click);

回答3:

Use a lambda to close over the data that you want to use in your event handler:

p.Click += (s, args) => 
    P_Click(reader1["desig_prd"].ToString(), (float)reader1["prix_prd"]);

回答4:

You misunderstood how events work.

p.Click is the event.

P_Click is the event handler.

You don't send the sender and event args - because the event does. So to hook the event all you need is p.Click += new System.EventHandler(P_Click); or event simply p.Click += P_Click;

You don't need MyEventArgs (at least not for this case), and instead, just calculate these values in the event hadler itself:

public void P_Click(Object sender, EventArgs e)
{
    var design = reader1["desig_prd"].ToString();
    var prix = (float)reader1["prix_prd"];
    ...
}

来源：https://stackoverflow.com/questions/22256284/method-name-expected-c-sharp

标签

event-handling