C # Delegate event self-understanding

It's hard for beginners to say that C # delegates and events, but it's easy to jump over it.

I don't know how long this is going to be, why it's so hard for some people to be simple, okay, this is a must.

Requirements: Card reader, I want to go to the program to call the card issuer method, get the cards card number information

Ordinary people understand: very simple, card one side, click on the reading of the event can be

I: Want to make it public DLL, use event registration to implement read card number

1. New Class library readertest--"reader

Public Reader () {}--> Constructor (It also writes the method of connecting the card reader)

2. Defining delegates

public delegate void Readereventhandler (Cardinfo card);

3. Defining events

public event Readereventhandler Readerevent;

4. Event triggering method

protected virtual void Readercard (Cardinfo card)

{//Prevent possible multi-threaded synchronization issues.

ReadercardhandlerTmpevent = readercardevent;      if (tmpevent! = null) {tmpevent (e); }
}5. Information class public class cardinfo{//a,b property slightly public cardinfo (string a,string b) {assignment slightly}}

6. External method Interface class invocation method implements event data transfer channel port

public void Getcardinfo ()

{

Logical Method Processing Branch

ULONG Cardno;            int cardtype; int nret = Card_readcardno(&cardno, &cardtype);                if (nret = = 0) {string Cardno = cardno.tostring ("x8"); String cardtype = Cardtype.tostring (); Cardinfo card = new Cardinfo (cardno,cardtype); //Pass event method Readcard(card);            } else {Console.WriteLine ("Cannot connect to a card"); }

}

7. Build DLL

8. Use of interface classes (add references)

Instantiate class first

Registering events in Load

Reader. readercardevent + = new XZX. Readersu.readercard. Readercardhandler (readcard);

Readcard method Implementation is consistent with internal delegate parameters

private void Readcard(XZX. ReaderSU.ReaderCard.CARDINFO e) {string cardno = E.cardno;           string cardtype = E.cardtype; Update interface element this.                Invoke (new Action () = {Lblcardno.text = Cardno;                Lbltype.text = Cardtype;            Lbltime.text = DateTime.Now.ToString ("Yyyy-mm-dd HH:mm:ss");                   })); }

C # Delegate event self-understanding