C # (event triggering) callback function, perfect handling all kinds of incurable diseases!

Every time you write a blog, the first sentence is this: the programmer is very hard, in addition to writing procedures, but also to write a blog!

That's a lot of crap.

First: What is the case with a callback function?

By code: Give a simple example

//Event Sender    classDog {//1. Declaration of the Commission on the event;         Public Delegate voidAlarmEventHandler (Objectsender, EventArgs e); //2. Declaration of events;         Public EventAlarmEventHandler Alarm; //3. Write the function that raises the event;         Public voidOnalarm () {if( This. Alarm! =NULL) {Console.WriteLine ("\ n The dog called the Police: A thief came in, barking ~~~~~~~");  This. Alarm ( This,NewEventArgs ());//issue an alert            }        }    }    //Event Recipients    classHost {//4. Writing Event handlers        voidHosthandlealarm (Objectsender, EventArgs e) {Console.WriteLine ("master: Caught the thief! "); }        //5. Registering Event Handlers         PublicHost (dog dog) {dog. Alarm+=NewDog.alarmeventhandler (hosthandlealarm); }    }    //6. Now to trigger the event    classProgram {Static voidMain (string[] args) {Dog Dog=NewDog (); Host host=NewHost (dog); //current time, starting from December 31, 2008 23:59:50DateTime now =NewDateTime ( -, A, to, at, -, -); DateTime Midnight=NewDateTime ( .,1,1,0,0,0); //waiting for the midnight to comeConsole.WriteLine ("time passes by one second ...");  while(Now <midnight) {Console.WriteLine ("Current Time:"+Now ); System.Threading.Thread.Sleep ( +);//program pauses for one secondnow = Now. AddSeconds (1);//time increases by one second            }            //0 O'Clock Midnight Thief arrives, watchdog raises alarm eventConsole.WriteLine ("the midnight of the Black Moon:"+Now ); Console.WriteLine ("The thief crept into the master's house ."); Dog.            Onalarm ();        Console.ReadLine (); }    }

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C # (event triggering) callback function, perfect handling all kinds of incurable diseases!