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what is the meaning of ( object sender, System.EventArgs e )

richard_urichard_u Posts: 2Member

Hello,

what is the meaning of ( object sender, System.EventArgs e )
when they are together as parameters of function of event of
a button, like :
public void rotation_Click(object sender, System.EventArgs e);


Bye,

richard

Comments

  • iwilld0itiwilld0it Posts: 1,134Member
    Under .NET framework, by convention, all events have this format.

    The reasoning for the first argument is that a single event handler can be attached to the same event like so.

    [code]
    btnTestA.Click += new EventHandler(btnTest_Click);
    btnTestB.Click += new EventHandler(btnTest_Click);
    [/code]

    When btnTestA and btnTestB is clicked, the btnTest_Click event handler will be fired. The "object sender" portion will be a reference to whatever one of the buttons was clicked ...

    [code]
    private void btnTest_Click(object sender, EventArgs e)
    {
    Button test = sender as Button;

    // etc ...
    }
    [/code]

    The EventArgs portion is a way to pass extra information to the event handler. In the case above, EventArgs is a base class and no real extra information is passed. However, alot of events use a derivative of EventArgs, which contain extra information.




    :
    : Hello,
    :
    : what is the meaning of ( object sender, System.EventArgs e )
    : when they are together as parameters of function of event of
    : a button, like :
    : public void rotation_Click(object sender, System.EventArgs e);
    :
    :
    : Bye,
    :
    : richard
    :
    :

  • richard_urichard_u Posts: 2Member
    [b][red]This message was edited by richard_u at 2005-11-9 8:35:5[/red][/b][hr]
    Hello,

    I do not understand this answer.
    I want an easier Explaination.

    Bye,

    Richard


  • iwilld0itiwilld0it Posts: 1,134Member
    The "sender" argument is the object that raised the event. The EventArgs argument is extra information passed to the event.

    So if u clicked a button, then the sender would be the button that u have clicked.

    Plain and simple.

    Now the fact that ALL events follow this format is a matter of convention. It is a coding practice / pattern adopted by Mirosoft.

    If you do not understand this, then you really must pick up a .NET book, since most devote a full chapter to this topic.
  • EyveneenEyveneen Posts: 1Member
    I was looking for the same answer to your question. Maybe this link will help.

    http://msdn.microsoft.com/en-us/library/system.eventhandler.aspx
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