Someone mentioned to me that c# supports to use lambda expression as event handler, can anyone share with me some reference on this?
A code snippet is preferred.
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2 Answers
You can use a lambda expression to build an anonymous method, which can be attached to an event.
For example, if you make a Windows Form with a Button and a Label, you could add, in the constructor (after InitializeComponent()):
this.button1.Click += (o,e) =>
{
this.label1.Text = "You clicked the button!";
};
This will cause the label to change as the button is clicked.
4 Comments
devshorts
Yup. I also wanted to point this out regarding adding and removing anonymous event handlers: stackoverflow.com/questions/2051357/…
Reed Copsey
@devshorts Yes. It's not necessarily great if you need to unsubscribe as well.
Superbest
Aren't the braces redundant for single-statement method bodies?
Reed Copsey
@Superbest They're not necessary for single statement bodies - they don't hurt anything, though, and it makes it a bit more clear when reading in a post like this, which is why I wrote it that way.
try this example
public Form1()
{
InitializeComponent();
this.button1.Click += new EventHandler(button1_Click);
}
void button1_Click(object sender, EventArgs e)
{
}
The above event handler can be rewritten using this lambda expression
public Form1()
{
InitializeComponent();
this.button1.Click += (object sender, EventArgs e) = >
{
MessageBox.Show(“Button clicked!”);
};
}
