Hi guys, Im having problems converting my vb.net code into c# in order to achieve a raiseEvent like the following

In the dataOperations class I have the following event (1 of many)

Public Event returnUserDetails(ByVal name As String, ByVal username As String, ByVal pk As Integer)

then in a function were I process the user details search query from the database I call the event like

RaiseEvent returnUserDetails(name, username, pk)

now in the other class where I want to read these values I simply declare an object of type dataOperations class, and get the following method, which gives me access to the values

Protected Sub oDB_returnUserDetails(ByVal name As String, ByVal username As String, ByVal pk As Integer) Handles oDB.returnUserDetails

End Sub

.. I was wondering if its done in a similar way in c# as I did try to look up tutorials, but am confused with the delegates and how to create a simple event like the one I explained up in my post.

Thanks

This will help: http://msdn.microsoft.com/en-us/library/w369ty8x.aspx

 to raise  event in c# no need to use vb.net keyword RaiseEvent

just call like below

returnUserDetails(name, username, pk);

Refer : http://msdn.microsoft.com/en-us/library/aa645739(VS.71).aspx

Hi, many thanks for your replies

Im still stuck..

should the event declaration be as follows ?

public delegate void returnMessage(object sender, EventArgs e);

or like vb.net public event returnMessage(string message);

I want to be able to pass in the message myself depending on the result of the function..

public delegate void returnMessage(Object sender, EventArgs e);
public event returnMessage myReturnMsg;

but how will i return the message.. as in I need to achieve something on the lines of

public event returnMessage myReturnMsg (string message);  - even though i know (string message) isn't valid..

but in my function

        private void returnDetails(string _firstName, string _lastName)
        {
            //processing here
            //when complete, raise the event to return message "Hello _firstName & _lastName"

            myReturnMsg(); // should the deletegate have the (string message) instead?
        }

based on your code that delegate is having one string argument, so you can pass directly like below

myReturnMsg("Hello _firstName & _lastName");

that string will be returned as argument where you are registering the event

else, you can define you own eventargs class by deriving from System.EventArgs with your own properties and pass that object  

Here's the code of what im trying to do, i removed all the extra stuff but this should give you an exact image of what im trying to achieve

//Inside dbOperations.cls

	public class clsDBOperations
    	{

		public delegate void returnMessage(string message);  
   		public event returnMessage myReturnMsg;  


		public void returnDetails(string _firstName, string _lastName)  
 		{  
     			//processing here  
     			//when complete, raise the event to return message "Hello"  
   
     			myReturnMsg("Hello"); 
 		} 
			
	}


//Inside Home.aspx

	public partial class Home : System.Web.UI.Page
    	{
		dbOperations dbo = new dbOperations();


protected void Page_Load(object sender, EventArgs e)
        {
            dbo.returnUserDetails();
        }

 public void dbo_myReturnMsg(string message)
		{
    			Response.Write(message);
		}


	}

 

Try something like this:

public class clsDBOperations
{
	public delegate void returnMessage(string message);
	public event returnMessage myReturnMsg = delegate { };
	
	public void returnDetails(string _firstName, string _lastName)
	{
		...
		myReturnMsg("Hello");
	}
}

public partial class Home : System.Web.UI.Page
{
	protected void Page_Load(object sender, EventArgs e)
	{
		dbOperations dbo = new dbOperations();
		dbo.myReturnMsg += dbo_myReturnMsg;
		dbo.returnUserDetails();
	}
	
	public void dbo_myReturnMsg(string message)
	{
		Response.Write(message);
	}
}

You need to subscribe to the event - dbo.myReturnMsg += dbo_myReturnMsg - in order to see it.

Also, when you raise an event, you need to make sure there are subscribers. You can either check to see whether the event is null - if (null != myReturnMsg) myReturnMsg("Hello"); - or add an empty handler within the class.

The standard convention with .NET is that event handlers should follow the same syntax. The first parameter should be an object called "sender", and the second should be a type derived from EventArgs. Also, if your class is not sealed, there should be a protected virtual method called "OnEventName" which is responsible for raising the event. This means that derived classes can raise the event, and can also override the method to receive notification when the event is raised. Combining these guidelines with the recommended casing rules would give something like this:

public class ReturnMessageEventArgs : EventArgs
{
	private readonly string _message;
	
	public ReturnMessageEventArgs(string message)
	{
		_message = message;
	}
	
	public string Message
	{
		get { return _message; }
	}
}

public class DBOperations
{
	public event EventHandler<ReturnMessageEventArgs> MyReturnMsg;
	
	protected virtual void OnMyReturnMsg(ReturnMessageEventArgs e)
	{
		EventHandler<ReturnMessageEventArgs> handler = MyReturnMsg;
		if (null != handler) handler(this, e);
	}
	
	public void ReturnUserDetails()
	{
		...
		OnMyReturnMessage(new ReturnMessageEventArgs("Hello"));
	}
}

public partial class Home : System.Web.UI.Page
{
	protected void Page_Load(object sender, EventArgs e)
	{
		DBOperations dbo = new DBOperations();
		dbo.MyReturnMsg += dbo_MyReturnMsg;
		dbo.ReturnUserDetails();
	}
	
	public void dbo_MyReturnMsg(object sender, ReturnMessageEventArgs e)
	{
		Response.Write(e.Message);
	}
}