blocks|key|3043814|text|EventArgs+e是一个名为e的参数，它包含事件数据，有关详细信息，请参阅EventArgs+MSDN页面。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|3043815|Object+Sender是一个名为Sender的参数，它包含对引发事件的控件/对象的引用。|3043816|事件参数类：http://msdn.microsoft.com/en-us/library/system.eventargs.aspx|3043817|示例：|3043818|protected+void+btn_Click+(object+sender,+EventArgs+e){
+++Button+btn+=+sender+as+Button;
+++btn.Text+=+"clicked!";
}|code-block|syntax|javascript|3043819|编辑：单击按钮时，将触发btn_Click事件处理程序。"object+sender“部分将引用所单击的按钮|BOLD|3043820|entityMap|0|LINK|mutability|MUTABLE|url|http://msdn.microsoft.com/en-us/library/system.eventargs.aspx^0|0|B|0|0|D|0|6|1P|0|0|0|0|0|3|0^^$0|@$1|2|3|4|5|6|7|11|8|@$9|12|A|13|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|14|8|@$9|15|A|16|B|C]]|D|@]|E|$]]|$1|H|3|I|5|6|7|17|8|@]|D|@$9|18|A|19|1|1A]]|E|$]]|$1|J|3|K|5|6|7|1B|8|@]|D|@]|E|$]]|$1|L|3|M|5|N|7|1C|8|@]|D|@]|E|$O|P]]|$1|Q|3|R|5|6|7|1D|8|@$9|1E|A|1F|B|S]]|D|@]|E|$]]|$1|T|3|-4|5|6|7|1G|8|@]|D|@]|E|$]]]|U|$V|$5|W|X|Y|E|$Z|10]]]]

<code>EventArgs e</code> is a parameter called e that contains the event data, see the EventArgs MSDN page for more information.

<code>Object Sender</code> is a parameter called Sender that contains a reference to the control/object that raised the event.

Event Arg Class: <a href="http://msdn.microsoft.com/en-us/library/system.eventargs.aspx" rel="noreferrer">http://msdn.microsoft.com/en-us/library/system.eventargs.aspx</a>

Example:

<pre><code>protected void btn_Click (object sender, EventArgs e){
 Button btn = sender as Button;
 btn.Text = "clicked!";
}
</code></pre>

Edit:
When Button is clicked, the btn_Click event handler will be fired. The "object sender" portion will be a reference to the button which was clicked

blocks|key|198133|text|按照惯例，这两个参数(或的变体)与所有事件一起发送。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|198134|198135|sender：已引发event|unordered-list-item|offset|length|style|CODE|198136|e的对象EventArgs的实例，在许多情况下，包括从EventArgs继承的对象。包含有关事件的其他信息，有时还提供处理事件的代码以某种方式更改事件的功能。|198137|198138|对于您提到的事件，这两个参数都不是特别有用。永远只有一个页面引发事件，并且EventArgs是Empty，因为没有关于事件的进一步信息。|198139|分别查看这两个参数，下面是一些有用的示例。|198140|sender|198141|假设一个表单上有多个按钮。这些按钮可能包含一个描述单击它们应该做什么的Tag。您可以使用相同的处理程序处理所有Click事件，并根据sender执行不同的操作|198142|private+void+HandleButtonClick(object+sender,+EventArgs+e)
{
++++Button+btn+=+(Button)sender;
++++if(btn.Tag+==+"Hello")
++++++MessageBox.Show("Hello")
++++else+if(btn.Tag+==+"Goodbye")
+++++++Application.Exit();
++++//+etc.
}|code-block|syntax|javascript|198143|免责声明:这是一个人为的例子；不要那样做！|198144|e|198145|有些事件是可以取消的。他们发送CancelEventArgs而不是EventArgs。此对象在事件args上添加一个简单的布尔属性Cancel。处理此事件的代码可以取消此事件：|198146|private+void+HandleCancellableEvent(object+sender,+CancelEventArgs+e)
{
++++if(/*+some+condition*/)
++++{
+++++++//+Cancel+this+event
+++++++e.Cancel+=+true;
++++}
}|198147|entityMap^0|0|0|0|6|0|0|1|4|9|R|9|0|0|11|9|1B|5|0|0|0|6|0|Z|3|1J|5|1U|6|0|0|0|0|1|0|F|F|X|9|1T|6|0|0^^$0|@$1|2|3|4|5|6|7|19|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|1A|8|@]|9|@]|A|$]]|$1|C|3|D|5|E|7|1B|8|@$F|1C|G|1D|H|I]]|9|@]|A|$]]|$1|J|3|K|5|E|7|1E|8|@$F|1F|G|1G|H|I]|$F|1H|G|1I|H|I]|$F|1J|G|1K|H|I]]|9|@]|A|$]]|$1|L|3|-4|5|6|7|1L|8|@]|9|@]|A|$]]|$1|M|3|N|5|6|7|1M|8|@$F|1N|G|1O|H|I]|$F|1P|G|1Q|H|I]]|9|@]|A|$]]|$1|O|3|P|5|6|7|1R|8|@]|9|@]|A|$]]|$1|Q|3|R|5|6|7|1S|8|@$F|1T|G|1U|H|I]]|9|@]|A|$]]|$1|S|3|T|5|6|7|1V|8|@$F|1W|G|1X|H|I]|$F|1Y|G|1Z|H|I]|$F|20|G|21|H|I]]|9|@]|A|$]]|$1|U|3|V|5|W|7|22|8|@]|9|@]|A|$X|Y]]|$1|Z|3|10|5|6|7|23|8|@]|9|@]|A|$]]|$1|11|3|12|5|6|7|24|8|@$F|25|G|26|H|I]]|9|@]|A|$]]|$1|13|3|14|5|6|7|27|8|@$F|28|G|29|H|I]|$F|2A|G|2B|H|I]|$F|2C|G|2D|H|I]]|9|@]|A|$]]|$1|15|3|16|5|W|7|2E|8|@]|9|@]|A|$X|Y]]|$1|17|3|-4|5|6|7|2F|8|@]|9|@]|A|$]]]|18|$]]

Those two parameters (or variants of) are sent, by convention, with all events.

<ul>
<li><code>sender</code>: The object which has raised the event</li>
<li><code>e</code> an instance of <code>EventArgs</code> including, in many cases, an object which inherits from <code>EventArgs</code>. Contains additional information about the event, and sometimes provides ability for code handling the event to alter the event somehow.</li>
</ul>

In the case of the events you mentioned, neither parameter is particularly useful. The is only ever one page raising the events, and the <code>EventArgs</code> are <code>Empty</code> as there is no further information about the event.

Looking at the 2 parameters separately, here are some examples where they are useful.

<h2><code>sender</code></h2>

Say you have multiple buttons on a form. These buttons could contain a <code>Tag</code> describing what clicking them should do. You could handle all the <code>Click</code> events with the same handler, and depending on the <code>sender</code> do something different

<pre><code>private void HandleButtonClick(object sender, EventArgs e)
{
 Button btn = (Button)sender;
 if(btn.Tag == "Hello")
 MessageBox.Show("Hello")
 else if(btn.Tag == "Goodbye")
 Application.Exit();
 // etc.
}
</code></pre>

Disclaimer : That's a contrived example; don't do that!

<h2><code>e</code></h2>

Some events are cancelable. They send <code>CancelEventArgs</code> instead of <code>EventArgs</code>. This object adds a simple boolean property <code>Cancel</code> on the event args. Code handling this event can cancel the event:

<pre><code>private void HandleCancellableEvent(object sender, CancelEventArgs e)
{
 if(/* some condition*/)
 {
 // Cancel this event
 e.Cancel = true;
 }
}
</code></pre>

In case of <code>Page_Load</code>, <code>Init</code> and other page events, what is the use of these <code>(object sender, EventArgs e)</code> parameters?

Examples would be more helpful.

What is the use of "object sender" and "EventArgs e" parameters?

对于Page_Load、Init和其他页面事件，这些(object sender, EventArgs e)参数的用途是什么？示例会更有帮助。

问“对象发送者”和"EventArgs e“参数的用途是什么？
EN

社区

活动

资源

关于

腾讯云开发者

热门产品

热门推荐

更多推荐

问“对象发送者”和"EventArgs e“参数的用途是什么？EN

社区

活动

资源

关于

腾讯云开发者

热门产品

热门推荐

更多推荐

问“对象发送者”和"EventArgs e“参数的用途是什么？
EN