C# Know how many EventHandlers are set?

Question

As we all know, we can create an EventHandler and add methods to it N number of times. Like:

   // Declare and EventHandler     
   public event EventHandler InternetConnectionAvailableEvent;
    private void OnInternetConnectionAvailableEvent()
    {
        if (InternetConnectionAvailableEvent != null)
        {
            EventHandler handle = InternetConnectionAvailableEvent;

            EventArgs e = EventArgs.Empty;
            handle(this, e);
        }
    }


   // IN OTHER CLASS WHERE I USE THE EVENT
   // Set the method name to handle the event    
   monitorInternet.InternetConnectionAvailableEvent += HandleInternetConnectionEvent;

    void HandleInternetConnectionEvent(object sender, EventArgs e)
    {
        if (syncContext != null)
        {
            MonitorInternetConnection mic = (MonitorInternetConnection)sender;
            if (mic != null)
            {
                syncContext.Post(o => InternetConnected(), null);
            }
        }
    }

   // To remove
   monitorInternet.InternetConnectionAvailableEvent -= null; 

UPDATE :

   // To remove it should be 
   monitorInternet.InternetConnectionAvailableEvent -= HandleInternetConnectionEvent;  // CORRECT

Same method can be called multiple times without removing it.

If I make monitorInternet.InternetConnectionAvailableEvent -= null;, all the event handlers be removed. I mean if it is set 2-3 times, and removed only once, by making it null, also all the other methods will be removed automatically.

I believe it will, but I just wanted to confirm with you experts. While googling I didn't get my required satisfactory answer.

Please correct me if am wrong.

Answer 1

To find the number of event handlers, you can use this code:

InternetConnectionAvailableEvent.GetInvocationList().Length;

The following code demonstrates that MyEvent -= null does not clear the list of handlers.

public static event EventHandler MyEvent;

[STAThread]
static void Main()
{
   MyEvent += (s,dea) => 1.ToString();
   MyEvent -= null;

   Console.WriteLine(MyEvent.GetInvocationList().Length);
   // Prints 1
   MyEvent = null;
   Console.WriteLine(MyEvent == null);
   // Prints true
}

To clear the list (which is probably never a good idea), you can set the event to null (as long as you are in the class that declared the event).

Answer 2

Delegates are removed by equality, so you're not removing anything from the invocation list because nothing in the invocation list would be null.