Question

I’ve used delegates when designing win forms in .NET… i.e. drag/drop a button, double click, and fill in the myButton_click event. I want to understand how to create and use user-defined delegates in C#.

How are user-defined delegates used and created in C# ?

Answer 1

I suggest reading a tutorial on the topic.

Basically, you declare a delegate type:

public delegate void MyDelegate(string message); 

Then you can either assign and call it directly:

MyDelegate = SomeFunction; MyDelegate('Hello, bunny'); 

Or you create an event:

public event MyDelegate MyEvent; 

Then you can add an event handler from outside like this:

SomeObject.MyEvent += SomeFunction; 

Visual Studio is helpful with this. After you entered the +=, just press tab-tab and it will create the handler for you.

Then you can fire the event from inside the object:

if (MyEvent != null) {     MyEvent('Hello, bunny'); } 

That’s the basic usage.