C # notes--delegates

A delegate is a type-safe object that points to another method (or methods) that will be called later in the program. In layman's words, a delegate is an object that can refer to a method, and when a delegate is created, an object that references the method is created, and the method can be called, that is, the delegate can invoke the method it refers to.

How do I use a delegate?

1. Defining delegate types

[Access modifier]delegate return type delegate name (formal parameter);

2. Declaring a Delegate object

Delegate name delegate instance name;

3. Create a Delegate object (determine which methods to bind to)

Delegate instance name =new delegate name (method of a class)

4. Using delegate invocation method

Delegate instance name (argument)

Considerations for Delegation:

1. Delegates and methods must have the same parameters.

2, delegates can call multiple methods, that is, a delegate object can maintain a list of callable methods instead of a separate method called multicast (multicast).

3. The method is increased and decreased by using the + = and-= operations.

4, the event is also a special delegate

Instance:

usingSystem;usingSystem.Collections.Generic;usingSystem.Linq;usingSystem.Text;usingDelegate;namespacedelegate{ Public Delegate intCall (intNUM1,intNUM2);//First step: Define the delegate type    classSimpleMath {//Multiplication Method         Public intMultiply (intNUM1,intnum2) {            returnNUM1 *num2; }        //Division Method         Public intDivide (intNUM1,intnum2) {            returnNUM1/num2; }    }}classtest{Static voidMain (string[] args) {Call objcall;//Step Two: Declare the delegate object//object of the Math classSimpleMath Objmath =NewSimpleMath (); //Step Three: Create a delegate object and associate the method with the delegateObjcall =NewCall (objmath.multiply); Call ObjCall1=NewCall (objmath.divide); Objcall+ = OBJCALL1;//add a method to a delegate//Objcall-= objCall1;//subtract a method from a delegate//invokes the delegate instance, executes objmath.multiply first, and then executes Objmath.divide        intresult = Objcall (5,3); System.Console.WriteLine ("The result is {0}", result);    Console.readkey (); }}

C # notes--delegates