...(object sender, System.EventArgs e)

Imran Adam

This is a really easy question i hope....... for example you have the following code; private void Form1_Load**(object sender, System.EventArgs e)** i would like to know what the bold part means?? im not too concerened about Form1_Load event, its just the parameters of any event. I cant seem to understand:mad: I have tried looking in books but had no success. Please help

Cheers :)

Not Active

hustler2005 wrote:

I have tried looking in books but had no success.

Don't understand why. There is plenty of documentation, and you couldn't find anything? sender is rather obvious, the sender of the event. EventArgs is the data generated from the event

only two letters away from being an asset

Imran Adam

sorry, what i meant is "i have had no success" in understanding what i have read. if someone could explain it a lil more clear/easier to understand?? it would make my day! :-D

Cheers :)

Scott Dorman

As Mark said, there is already a lot of information about this online. Anyway, the sender parameter is an object representation of the control that caused the event to be sent. It is an object, which means that you need to have some knowledge of what the actual sender is supposed to be if you want to use it inside the event handler. In order to use the sender you need to cast it to the appropriate type. In the case of your example, you would need to do one of the following:

private void Form1_Load(object sender, System.EventArgs e)
{
Form f = sender as Form;
if (f != null)
{
// do something here
}
}

or

private void Form1_Load(object sender, System.EventArgs e)
{
Form f = (Form)sender;
// do something here
}

To me, the preferred way is the first one since it is a bit safer. The e parameter represents the "EventArgs" of the event. In reality, EventArgs is a class that is used to hold the data generated by the event that could be used within the event handler. All events should use either the System.EventArgs class or a custom (derived) System.EventArgs class. The default System.EventArgs class maintains no data about the event.

Scott.

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Imran Adam

Thanks Scott/Matt for your input. You mention there is alot of documentation online, can you suggest a good starting point?? This would be very help indeed.

Cheers :)

Scott Dorman

Sure, a good starting point would probably be MSDN. Here are some links: EventArgs Class (System)[^] EventHandler Delegate (System)[^] Events and Delegates[^] Consuming Events[^]

Scott.

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