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Example of subscribing to and firing events

/ Published in: C#
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See [Raise and Handle Events Generically](http://snipplr.com/view/15033/raise-and-handle-events-generically/) for a better way to use events (generically) and links to best practices in .NET events.

This example should be used as a Console program and will simply write a line of text to the console. It shows how to create an event handler in a class, have that event handler fire an event with custom information, and how to subscribe to that event and use its data. I hope it is straightforward enough.

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  1. using System;
  2.  
  3. namespace testConsole
  4. {
  5.     class Program
  6.     {
  7.         static void Main(string[] args)
  8.         {
  9.             Test myTest = new Test();
  10.             // Add event handler to the event
  11.             myTest.TestEvent += new EventHandler(myTest_TestEvent);
  12.             myTest.fireEvent();
  13.             Console.ReadLine(); // Keep console window open
  14.         }
  15.  
  16.         static void myTest_TestEvent(object sender, EventArgs e)
  17.         {
  18.             if (e is TestEventArgs)
  19.             {
  20.                 TestEventArgs data = e as TestEventArgs;
  21.                 Console.WriteLine(data.Message);
  22.             }
  23.         }
  24.     }
  25.  
  26.     class Test
  27.     {
  28.         public event EventHandler TestEvent;
  29.         public Test()
  30.         {
  31.         }
  32.         public void fireEvent()
  33.         {
  34.             // Always check if the EventHandler is null (no subscribers)
  35.             var handler = TestEvent;
  36.             if (handler != null)
  37.             {
  38.                 handler(this, new TestEventArgs("Event Fired"));
  39.             }
  40.         }
  41.     }
  42.  
  43.     class TestEventArgs : EventArgs
  44.     {
  45.         public string Message { get; private set; }
  46.         public TestEventArgs(string message)
  47.         {
  48.             this.Message = message;
  49.         }
  50.     }
  51. }

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