How new operator works with delegates in C#

Question

In this code snippet how does new MyDel(this.WelcomeUser) work? What happens in memory, I know that delegate is reference type, so is there an object created in heap and which type of object is it - MyDel? what is exactly this.WelcomeUser? Is it a reference to a method?

using System;
namespace SampleApp {
public delegate string MyDel(string str);

class EventProgram {
  event MyDel MyEvent;

  public EventProgram() {
     this.MyEvent += new MyDel(this.WelcomeUser);
  }
  public string WelcomeUser(string username) {
     return "Welcome " + username;
  }
  static void Main(string[] args) {
     EventProgram obj1 = new EventProgram();
     string result = obj1.MyEvent("Tutorials Point");
     Console.WriteLine(result);
  }
 }
}

Answer 1

how does new MyDel(this.WelcomeUser) work?

It is a call to a constructor, with this.WelcomeUser as an argument.

public delegate string MyDel(string str);

Is a Type definition. The compiler uses this to generate a class deriving from System.Delegate. Note that this was designed before C# had generics.

what is exactly this.WelcomeUser?

It is the name of a method. In C# (and C, C++ etc) a method is always followed by a parameter (or argument) list, even if that list is empty: SomeMethod().
Omitting the list is the equivalent of adress-of.

It becomes clearer when you look at VB.NET, the equivalent code is

MyEvent += new MyDel(this.WelcomeUser);       // C#

AddHandler MyEvent, AddressOf Me.WelcomeUser  ' VB

And from C# 2 on, you can use the short notation:

MyEvent += this.WelcomeUser;       // modern C#