How make arrays of delegates and use this array?

Question

I have to write class Eve to make some code below:

class MainClass
  {    int sum = 5;
    public  void add (int x)
    {
      sum += x;
    }
    public static void write (int x)
    {
      Console.WriteLine("x = " + x);
    }
    public static void Main (string[] args)
    {
      Eve p = new Eve();
      MainClass m = new MainClass(); 
      p.registrate(m.add);
      p.registrate(write);
      p.registrate (delegate (int x) { 
                      System.Console.WriteLine(" I have {0} ", x);
                    }); 
      p.registrate (x => System.Console.WriteLine (" Square : {0} ", x * x));
      p.run(10);
      p.run(5);
                  Console.WriteLine(" Sum is {0} ", m.sum);
    }
  }

Output:

x = 10

I have 10

Square : 100

x = 5

I have 5

Square : 25

Sum is 20

So think I have to use delegates. And method registarte should add delegate to array of delegates.

I wrote code like this but i dint sure is wright.

 public class Eve
    {
        int i;
        public Eve()
        {
            i = 0;
        }
        public delegate void ComputeDelegate(int x);

        ComputeDelegate[] delegates = new ComputeDelegate[2];

        public void registrate(ComputeDelegate a)
        {
            if (i == 2) i = 0;
            delegates[i] += a;
            i++;
        }

        public void run()
        {
            //delegates[0].;
        }
}
        public class MainClass
        {
            int sum = 5;
            public void add(int x)
            {
                sum += x;
            }
            public void write(int x)
            {
                Console.WriteLine("x = " + x);
            }
            static void Main()
            {
                Eve proc1 = new Eve();
                MainClass m = new MainClass();

                proc1.registrate(m.add);
                proc1.registrate(m.write);


            }
        }
    }

I have problem how I have to write method run? Or this same but in another way how i can lunch method wich is in delegate array?

Why are you writing your own Event class instead of just using the event keyword in C#? — Servy
– Servy, Commented May 13, 2013 at 17:14
I'm guessing because the assignment is to help understand how and why event might be implemented? — Mikeb
– Mikeb, Commented May 13, 2013 at 17:15
@Mikeb Or he may just not know that there is already an event keyword. I'd like to hear from him why he can't use it. — Servy
– Servy, Commented May 13, 2013 at 17:19
This name class is only name class not more. I ask how to run method in delegate array. — Aku
– Aku, Commented May 13, 2013 at 17:25
This could be implemented using the event keyword in C#, or by using multicast delegates and operator +/-/+=/-=, or by calling Delegate.Combine/Delegate.Remove instead of using an array. See also this question: stackoverflow.com/questions/14197857/… — Sam Harwell
– Sam Harwell, Commented May 13, 2013 at 17:49

Guffa · Accepted Answer · 2013-05-13 17:28:53Z

5

As you want to add delegates, a list would be better than an array. There are generic delegate types that you can use instead of creating a custom delegate type:

List<Action<int>> delegates = new List<Action<int>>();

To register a delegate, just add it to the list:

public void registrate(Action<int> a) {
  delegates.Add(a);
}

To use the delegates, just call them by putting parentheses after them. The same syntax as with a regular method. Example:

int input = 5;
foreach (Action<int> a in delegates) {
  a(input);
}

answered May 13, 2013 at 17:28

Guffa

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Comments

Jeppe Stig Nielsen · Accepted Answer · 2013-05-13 17:30:03Z

1

It looks like you simply need delegates[0](x); where x is the int you want to pass to the 0th entry in the array.

(delegates has type ComputeDelegate[]. Your ComputeDelegate type has the same signature and return type as System.Action<int>, of course.)

answered May 13, 2013 at 17:30

Jeppe Stig Nielsen

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1 Comment

Aku Over a year ago

Yes exactly this I need. I think is easy question but me is totally newibie in C# i wrote about 50 line of code in this language.

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