DelegateAndEventSample.cs

using System;

namespace ConsoleApplication1
{
    // Declare delegate
    public delegate int mathDelegate(int a, int ab);

    class EventDelegateClass
    {
        // event of type mathDelegate
        public event mathDelegate mathEvenHandler;

        public int Sum(int x, int y)
        {
            var s = x + y;

            if (s > 5)
            {
                // check for any event listeners subscribed.
                if (mathEvenHandler != null)
                {
                    // call the event listener.
                    mathEvenHandler.Invoke(4, 5);
                }
            }
            return s;

        }

        public int Multiply(int a, int b)
        {
            var s = a * b;
            return s;
        }

    }

    class Test
    {
        static void Main(string[] args)
        {
            EventDelegateClass edOjb = new EventDelegateClass();
            // subscribe to event
            edOjb.mathEvenHandler += EventListener;

            // Create delegate
            mathDelegate delObj = null;
            // point method to delegate (Multicast).
            delObj += edOjb.Sum;
            delObj += edOjb.Multiply;
            // Invoke delegate
            var result = delObj.Invoke(2, 4);

            // the result is the value of last call
            Console.WriteLine("Delegate call result: "+result);
            Console.ReadLine();
        }

        static int EventListener(int p, int q)
        {
            var temp = p + q;
            Console.WriteLine("Sum in event listener: " + temp);
            return temp;
        }
    }
}