How can I make my own event in C

Question

User · Answer

I have a full discussion of events and delegates in my events article. For the simplest kind of event, you can just declare a public event and the compiler will create both an event and a field to keep track of subscribers:

public event EventHandler Foo;

If you need more complicated subscription/unsubscription logic, you can do that explicitly:

public event EventHandler Foo
{
    add
    {
        // Subscription logic here
    }
    remove
    {
        // Unsubscription logic here
    }
}

User · Answer

You can declare an event with the following code   public event EventHandler MyOwnEvent    A custom delegate type instead of EventHandler can be used if needed   You can find detailed information tutorials on the use of events in  NET in the article Events Tutorial  MSDN

User · Answer

to do it we have to know the three components    the place responsible for firing the Event the place responsible for responding to the Event the Event itself  a  Event  b  EventArgs   c  EventArgs enumeration    now lets create Event that fired when a function is called   but I my order of solving this problem like this  I m using the class before I create it    the place responsible for responding to the Event  NetLog OnMessageFired    delegate object o  MessageEventArgs args                when the Event Happened I want to Update the UI            this is WPF Window  WPF Project            this Dispatcher Invoke      gt                        LabelFileName Content   args ItemUri              LabelOperation Content   args Operation              LabelStatus Content   args Status                    NetLog is a static class I will Explain it later  the next step is   the place responsible for firing the Event    this is the sender object  MessageEventArgs Is a class I want to create it  and Operation and Status are Event enums NetLog FireMessage this  new MessageEventArgs  File1 txt   Operation Download  Status Started    downloadFile   service DownloadFile item Uri   NetLog FireMessage this  new MessageEventArgs  File1 txt   Operation Download  Status Finished       the third step   the Event itself   I warped The Event within a class called NetLog  public sealed class NetLog       public delegate void MessageEventHandler object sender  MessageEventArgs args        public static event MessageEventHandler OnMessageFired      public static void FireMessage Object obj MessageEventArgs eventArgs                if  OnMessageFired    null                        OnMessageFired obj  eventArgs                      public class MessageEventArgs   EventArgs       public string ItemUri   get  private set        public Operation Operation   get  private set        public Status Status   get  private set         public MessageEventArgs string itemUri  Operation operation  Status status                ItemUri   itemUri          Operation   operation          Status   status           public enum Operation       Upload Download    public enum Status       Started Finished     this class now contain the Event  EventArgs and EventArgs Enums and the function responsible for firing the event  sorry for this long answer

User · Answer

Here s an example of creating and using an event with C   using System   namespace Event Example         First we have to define a delegate that acts as a signature for the       function that is ultimately called when the event is triggered        You will notice that the second parameter is of MyEventArgs type        This object will contain information about the triggered event      public delegate void MyEventHandler object source  MyEventArgs e          This is a class which describes the event to the class that recieves it        An EventArgs class must always derive from System EventArgs      public class MyEventArgs   EventArgs               private string EventInfo          public MyEventArgs string Text                        EventInfo   Text                    public string GetInfo                         return EventInfo                         This next class is the one which contains an event and triggers it       once an action is performed  For example  lets trigger this event       once a variable is incremented over a particular value  Notice the       event uses the MyEventHandler delegate to create a signature       for the called function      public class MyClass               public event MyEventHandler OnMaximum          private int i          private int Maximum   10          public int MyValue                       get                               return i                            set                               if value  lt   Maximum                                        i   value                                    else                                         To make sure we only trigger the event if a handler is present                       we check the event to make sure it s not null                      if OnMaximum    null                                                OnMaximum this  new MyEventArgs  You ve entered                                 value ToString                                    but the maximum is                                 Maximum ToString                                                                                 class Program                 This is the actual method that will be assigned to the event handler           within the above class  This is where we perform an action once the           event has been triggered          static void MaximumReached object source  MyEventArgs e                        Console WriteLine e GetInfo                        static void Main string   args                          Now lets test the event contained in the above class              MyClass MyObject   new MyClass                MyObject OnMaximum    new MyEventHandler MaximumReached                for int x   0  x  lt   15  x                                  MyObject MyValue   x                             Console ReadLine

[c#] How can I make my own event in C#?

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