Raise an event of a class from a different class in C#

This is not possible, Events can only be risen from inside the class. If you could do that, it would defeat the purpose of events (being able to rise status changes from inside the class). I think you are misunderstanding the function of events - an event is defined inside a class and others can subscribe to it by doing

obj.AfterSearch += handler; (where handler is a method according to the signature of AfterSearch). One is able to subscribe to the event from the outside just fine, but it can only be risen from inside the class defining it.

It is POSSIBLE, but using clever hack.

Inspired by http://netpl.blogspot.com/2010/10/is-net-type-safe.html

If you don't believe, try this code.

using System;
using System.Runtime.InteropServices;

namespace Overlapping
{
    [StructLayout(LayoutKind.Explicit)]
    public class OverlapEvents
    {
        [FieldOffset(0)]
        public Foo Source;

        [FieldOffset(0)]
        public OtherFoo Target;
    }

    public class Foo
    {
        public event EventHandler Clicked;

        public override string ToString()
        {
            return "Hello Foo";
        }

        public void Click()
        {
            InvokeClicked(EventArgs.Empty);
        }

        private void InvokeClicked(EventArgs e)
        {
            var handler = Clicked;
            if (handler != null)
                handler(this, e);
        }
    }

    public class OtherFoo
    {
        public event EventHandler Clicked;

        public override string ToString()
        {
            return "Hello OtherFoo";
        }

        public void Click2()
        {
            InvokeClicked(EventArgs.Empty);
        }

        private void InvokeClicked(EventArgs e)
        {
            var handler = Clicked;
            if (handler != null)
                handler(this, e);
        }

        public void Clean()
        {
            Clicked = null;
        }
    }

    class Test
    {
        public static void Test3()
        {
            var a = new Foo();
            a.Clicked += AClicked;
            a.Click();
            var o = new OverlapEvents { Source = a };
            o.Target.Click2();
            o.Target.Clean();

            o.Target.Click2();
            a.Click();
        }

        static void AClicked(object sender, EventArgs e)
        {
            Console.WriteLine(sender.ToString());
        }
    }
}

You can write a public method on the class you want the event to fire from and fire the event when it is called. You can then call this method from whatever user of your class.

Of course, this ruins encapsulation and is bad design.