C# Discussion Boards - CodeProject

Re: Who am I? Detecting the &quot;current&quot; control for a handler

26-Sep-07 2:41

no, "this" is the form. The code you described won't even compile... I need to know the index of the current control inside the ArrayList of controls aRelationshipComboBoxes[]...

TJoe26-Sep-07 2:48

Re: Who am I? Detecting the &amp;quot;current&amp;quot; control for a handler

26-Sep-07 2:48

I think there is probably something else wrong. If you use Reflector[^] you can see that the SelectedIndexChanged event is always fired by a ComboBox using "this" as the sender. Check out the OnSelectedIndexChanged(EventArgs) method.

I would recommend setting the Name property on the ComboBoxes that you are creating (assuming you are not already doing that).

Can you put together a small sample project and send it over?

Take care,
Tom

-----------------------------------------------
Check out my blog at http://tjoe.wordpress.com

JoeRip26-Sep-07 2:52

Re: Who am I? Detecting the &quot;current&quot; control for a handler

26-Sep-07 2:52

Ignore my code for a second, it's probably confusing the issue.

Generically, how do you get the identity of the control for whom a handler is executing? I believe I'm looking for the C# equivalent of the VB "Me" keyword, here.

TJoe26-Sep-07 3:01

Re: Who am I? Detecting the &quot;current&quot; control for a handler

26-Sep-07 3:01

The "sender" parameter is the control that fired the event. I'm assuming that is what you are asking. The C# equilvalent of the VB.Net "Me" is "this".

So if you have two combo boxes and you hook them both up to the same event handler like:

private ComboBox comboBox1 = new ComboBox();
private ComboBox comboBox2 = new ComboBox();
  
private void CreateComboBoxes() {
	this.comboBox1 = new ComboBox();
	this.comboBox2 = new ComboBox();
	// 
	// comboBox1
	// 
	this.comboBox1.Location = new System.Drawing.Point(51, 157);
	this.comboBox1.Name = "comboBox1";
	this.comboBox1.Size = new System.Drawing.Size(121, 21);
	this.comboBox1.TabIndex = 0;
	this.comboBox1.SelectedIndexChanged += new System.EventHandler(this.comboBox_SelectedIndexChanged);
	// 
	// comboBox2
	// 
	this.comboBox2.Location = new System.Drawing.Point(51, 184);
	this.comboBox2.Name = "comboBox2";
	this.comboBox2.Size = new System.Drawing.Size(121, 21);
	this.comboBox2.TabIndex = 1;
	this.comboBox2.SelectedIndexChanged += new System.EventHandler(this.comboBox_SelectedIndexChanged);
	// 
	// Form1
	// 
	this.Controls.Add(this.comboBox2);
	this.Controls.Add(this.comboBox1);
}
  
private void comboBox_SelectedIndexChanged(Object sender, EventArgs e) {
	if (sender == this.comboBox1) {
		// Sender is comboBox1
	}
	else if (sender == this.comboBox2) {
		// Sender is comboBox2
	}
}

Then you can use the sender to distinguish the control that fired the event. The sender will be the ComboBox whose selected indexed changed regardless of how it changed (e.g. through code or through user interaction).

In the comboBox_SelectedIndexChanged() method, "this" refers to the Form because the method is defined in the Form class.

Take care,
Tom

-----------------------------------------------
Check out my blog at http://tjoe.wordpress.com

JoeRip26-Sep-07 3:07

Re: Who am I? Detecting the &quot;current&quot; control for a handler

26-Sep-07 3:07

yeah, ignore my "Me" comment, too. I include too much.

Okay, write the second handler without typing "combobox1" or "combobox2". My controls are located in ListArrays. I can only refer to them by knowing what their index is.

So in comboBox_SelectedIndexChanged(Object sender, EventArgs e), I need to know which of my two comboboxes is executing. "sender" turns out to be the combobox you clicked on, UNLESS you actually clicked on ComboBox1 and the code therein caused the DataSource for ComboBox2 to change. At that point, ComboBox2 receives a "SelectedIndexChanged" message, whose "sender" is ComboBox1.

So - in comboBox_SelectedIndexChanged(Object sender, EventArgs e) - how can you figure out which control is having it's Selected Index changed, without referring to it by name?

TJoe26-Sep-07 3:16

Re: Who am I? Detecting the &quot;current&quot; control for a handler

26-Sep-07 3:16

I would need to see a sample of this happening. What I'm saying is that if the SelectedIndexChanged is being fired for the ComboBox2 (because of a DataSource change or any other reason) then the sender will always be ComboBox2. This is hard-coded into the .Net framework.

I think there is something else wrong in your code. The sender will always be the ComboBox that had it's selected index changed (regardless of whether the user clicked in the first ComboBox or not). So there must be a problem with how the events are hooked up or with something else being done before the event is fired.

Take care,
Tom

-----------------------------------------------
Check out my blog at http://tjoe.wordpress.com

JoeRip26-Sep-07 3:18

Re: Who am I? Detecting the &quot;current&quot; control for a handler

26-Sep-07 3:18

Sorry! My bug. I was binding the same handler to two different combo types. I gotta stop working all night.

So then - I can always use "sender" to know which control instance received the event? Yay! I can go to bed now!

JoeRip26-Sep-07 3:21

Re: Who am I? Detecting the &quot;current&quot; control for a handler

26-Sep-07 3:21

Oh, and thanks. I'm tired, so I'm not being as clear as I should be.

BTW, if you know any better way to find out who "the current control" is in my case than what I am doing ("I don't have a reference for myself, so here, find Sender in this ArrayList and return me the Index"), I'd take it. That feels very obtuse to me...

Good night!

TJoe26-Sep-07 3:25

Re: Who am I? Detecting the &quot;current&quot; control for a handler

26-Sep-07 3:25

If it's always one main ComboBox to one secondary ComboBox, then I would use a Dictionary[^]. This way you can use the first ComboBox as the Key, then quickly obtain the secondary ComboBox (which would be the value).

Take care,
Tom

-----------------------------------------------
Check out my blog at http://tjoe.wordpress.com

JoeRip26-Sep-07 3:34

Re: Who am I? Detecting the &quot;current&quot; control for a handler

26-Sep-07 3:34

I wish. It's an arbitrary number of "rows", each of which is composed of 10 controls.

I keep 10 ArrayLists(), one for each "column" in each row. Each ArrayList contains the control that goes in that "column" at that "row" (Index).

So at every point in my code where I need to refer to those controls, I use

. ((TypeOfControl)aNameOfArray[RowNum]).Property

Each column of controls shares an event handler. To find out which control is actually being fired upon, I have to use this:

. int i =aNameOfArray.IndexOf((TypeOfControl)sender);

Now that I have "i" (the index of this control in that specific ArrayList), I can use it to manage the other controls in that "row".

It doesn't seem so bad now, but while I was struggling with that bug I desparately wished for a shortcut like "thisControl" which I could refer to...

What would make life easier would be if ArrayList allowed multiple dimensions. However, it's really a Collection and apparently Collections don't allow that.

TJoe26-Sep-07 3:42

Re: Who am I? Detecting the &amp;quot;current&amp;quot; control for a handler

26-Sep-07 3:42

To acheive multiple dimensions you can have an ArrayList of ArrayLists. If you are using .Net 2.0 then I would recommend using a List[^].

For your problem above, I would probably create a main ArrayList that holds ArrayLists. So for each row of controls you would create an ArrayList and add your controls, then add that ArrayList to the main ArrayList in the proper position.

Then to determine what row a given control exists in, I would use a Dictionary. Declared as "Dictionary<control, int32="">", the dictionary would map a control to it's associated row in the main ArrayList.

This way you could easily add additional controls to the row without having to create a new ArrayList.

Take care,
Tom

-----------------------------------------------
Check out my blog at http://tjoe.wordpress.com

Luc Pattyn26-Sep-07 3:58

Luc Pattyn

26-Sep-07 3:58

FYI every Control has a Tag property (type: object), so you can store one reference there
to whatever you like. One ComboBox could point to another ComboBox, to an ArrayList, whatever.

Luc Pattyn [Forum Guidelines] [My Articles]

this weeks tips:
- make Visual display line numbers: Tools/Options/TextEditor/...
- show exceptions with ToString() to see all information
- before you ask a question here, search CodeProject, then Google

Re: Who am I? Detecting the &quot;current&quot; control for a handler

TJoe26-Sep-07 3:22

How to extract HTML code From any webpage using C#.Net

26-Sep-07 3:22

I would always assume that sender is the control instance that "fired" the event. The form is the one receiving the event. I use the word "assume", because it's really up to the person who coded the control. For the .Net framework controls, I have never seen an instance were sender was not the associated control. If there is then it would probably be considered a bug.

Take care,
Tom

-----------------------------------------------
Check out my blog at http://tjoe.wordpress.com

allivelu26-Sep-07 1:35

allivelu

26-Sep-07 1:35

How to extract html code any web site using C#.Net

I mean : http://www.yahoo.com----in that site find the Urls,Emailid,phone

Pls give code

Reddy

Re: How to extract HTML code From any webpage using C#.Net

Christian Graus26-Sep-07 1:46

Christian Graus

26-Sep-07 1:46

Grabbing the HTML is easy, the rest probably involves regular expressions to parse the string that contains the page.

Christian Graus - Microsoft MVP - C++

"I am working on a project that will convert a FORTRAN code to corresponding C++ code.I am not aware of FORTRAN syntax" ( spotted in the C++/CLI forum )

Re: How to extract HTML code From any webpage using C#.Net

Matthew Cuba26-Sep-07 2:00

Matthew Cuba

26-Sep-07 2:00

allivelu wrote:
How to extract html code any web site using C#.Net

I mean : http://www.yahoo.com----in that site find the Urls,Emailid,phone

I'm not sure exactly what you want. If you are looking to get the HTML for a webpage, load it in a WebBrowser object and use the DocumentText property to retrieve the HTML as a string.

If you are looking for the URLs, email, and phone numbers, you'll need to look at the string you got from calling browser.DocumentText for substrings that match the pattern of a URL, email address or phone number. The Regex class is what you might want to look at, since that is *really* helpful at doing pattern matching.

Good Luck!

It isn't enough to do well in life.
One must do good when and where one can.
Otherwise, what's the point?

Simulator

prog_omer_esmail26-Sep-07 1:13

prog_omer_esmail

26-Sep-07 1:13

i want to make something like windows simulation question ??????

if any one have any idea about creating this, Please reply quickly

many thanks

omer

ESTAN26-Sep-07 1:24

ESTAN

26-Sep-07 1:24

What do you want to do exactly?
And we all try to do our best, you cannot ask, please reply quickly.

pmarfleet26-Sep-07 1:47

pmarfleet

26-Sep-07 1:47

Your question makes no sense.

What does 'windows simulation question' mean?

Paul Marfleet

PaulPrice26-Sep-07 1:55

PaulPrice

26-Sep-07 1:55

Maybe he wants to simulate questions asked by Windows?? Not sure which ones! Would you like to save before closing maybe?

Paul

ESTAN26-Sep-07 2:02

ESTAN

26-Sep-07 2:02

I think that even we answered quickly and now we have to wait for him...

What are we simulating here? The lounge discussion board? :->

prog_omer_esmail26-Sep-07 3:12

prog_omer_esmail

26-Sep-07 3:12

So sorry for being late

i have a problem with internet connection

i want to make some thing like simulation questions in the microsoft certicates

thanks so much and sorry for being late

Best wishes

omer

J4amieC26-Sep-07 3:35

J4amieC

26-Sep-07 3:35

Your question still makes no sense. What do you mean by simulation questions?

---

How to get answers to your questions[^]

Pete O'Hanlon26-Sep-07 4:12

Pete O'Hanlon

26-Sep-07 4:12

I think I see. Are you looking to create a system which poses questions in the same way that the Microsoft exams are run? If so, you are going to need to have a database with questions and answers in them.

Deja View - the feeling that you've seen this post before.