C＃中的匿名方法是什么？

Question

有人可以解释一下C＃中的匿名方法（简单来说），并提供可能的例子

Answer 1

Anonymous methods were introduced into C# 2 as a way of creating delegate instances without having to write a separate method. They can capture local variables within the enclosing method, making them a form of closure .

An anonymous method looks something like:

delegate (int x) { return x * 2; }

and must be converted to a specific delegate type, eg via assignment:

Func<int, int> foo = delegate (int x) { return x * 2; };

... or subscribing an event handler:

button.Click += delegate (object sender, EventArgs e) {
    // React here
};

For more information, see:

• My article (written a long time ago) on delegate changes in C# 2
• MSDN on anonymous methods
• Chapter 5 of C# in Depth if you fancy buying my book :)

Note that lamdba expressions in C# 3 have almost completely replaced anonymous methods (although they're still entirely valid of course). Anonymous methods and lambda expressions are collectively described as anonymous functions .

Answer 2

Anonymous method is method that simply doesn't have name and this method is declared in place, for example:

Button myButton = new Button();
myButton .Click +=
delegate
{
    MessageBox.Show("Hello from anonymous method!");
};

Answer 3

An anonymous method is a block of code that is used where a method would usually be required and which does not have a name (hence anonymous).

MSDN has examples of using anonymous methods .

Answer 4

These are methods without name.

For example, ordinary method is:

public void Foo()
{
   Console.WriteLine("hello");
}

While anonymous method can be:

myList.ForEach(item => Console.WriteLine("Current item: " + item));

The code inside the ForEach is actually a method but has no name and you can't call it from the outside.