C # Anonymous delegate, anonymous function, lambda expression

The relationship between a type, a variable, and an instance.

Type "Variable" example

Types can create variables, entity classes can create instances, and instances can be stored in variables.

Second, the use of the Commission process:
1. Define the delegate (write a good signature);
2. Create a delegate variable;
3. Append the reference function (same signature) to the delegate variable.

Iii. The origin of lambda expressions

private void Button1_Click (object sender, EventArgs e)        {            //anonymous delegate    func<int, int> del            //type ' variable ' instance            //func is an anonymous delegate type, which is an unnamed type            //How to determine its signature: requires several data types as parameters (preceding parameter type, last specified return value type)            //can directly define a delegate variable            // anonymous function    delegate (int a) {return A;};            The difference from the normal function is that the function name is replaced with the delegate            //following expression, which is a variable defined by the anonymous delegate del refers to the process of an anonymous function            //and int a=1, is the same            //func< int, int> del =  delegate (int a) {return A;};            MessageBox.Show (Del (5). ToString ());            Later found that the anonymous function must be placed in the delegate, the parameter type has been determined, so there is a more concise wording, the parameter type is omitted            //There is a lambda expression            func<int, int> del = a + = { return A; };            MessageBox.Show (Del (6). ToString ());        }

Tips:

Define an anonymous delegate variable, like we're sure to build a gun, but the gun doesn't work, because it's just the stage of functional design , the function of the gun is: Give it a bullet (parameter), we get a high-speed flying bullet (return value);
Assigning a lambda expression to this delegate variable is like giving the gun a process of internal construction such as a barrel, a trigger, and then the gun can work.

Iv. events in the WinForm form

WinForm Form event: A variable defined with a predefined delegate (Eventhandle) (receives two parameters).
The form has a delegate variable, and all we do is add the function to the variable.

1.

Add a function to the form Load event

public partial class Form1:form    {public        Form1 ()        {            InitializeComponent ();        }        private void Form1_Load (object sender, EventArgs e)        {        }

An automatically generated expression

Go to definition to see the definition of the Load event

C # Anonymous delegate, anonymous function, lambda expression