Re: Treeview Node Select Problem - C# Discussion Boards

7-Feb-08 13:04

Dear All,

I have a treeview with several parent and child node. If I click on a parent, I want to invoke a method. If I click on a child , I want to invoke another method. The same method for the parents , and the same method for the childs.

+ Parent Node 1
- Child node 1
- Child node 1
+ Parent Node 2
- Child node 1

This is the code I dreamed to achieve this. But .. for some reason it doesn't work. If I click on the child, it works .. however, the parent method is not fired when I click on the parent. Can somebody point me in the right direction with whatever it is that I'm doing wrong ?

 private void treeView_AfterSelect(object sender, TreeViewEventArgs e)<br />
         {<br />
            if (e.Node.Parent.IsSelected)<br />
            {<br />
                MessageBox.Show("This is the parent node");<br />
            }<br />
<br />
            else<br />
            {<br />
                MessageBox.Show("This is a child node");<br />
            }<br />
        }

Thanks

Christian Graus7-Feb-08 13:06

7-Feb-08 13:06

Do you mean the after select event is not fired, or do you mean that the wrong message box shows ?

I'd probably set the tree view items up with tags so you can tell what level they are on. Or check if the node has children, if the tree is only ever one level.

Christian Graus - Microsoft MVP - C++

"also I don't think "TranslateOneToTwoBillion OneHundredAndFortySevenMillion FourHundredAndEightyThreeThousand SixHundredAndFortySeven()" is a very good choice for a function name" - SpacixOne ( offering help to someone who really needed it ) ( spaces added for the benefit of people running at < 1280x1024 )

Rick van Woudenberg7-Feb-08 13:11

7-Feb-08 13:11

Christian,

Thank you for replying so quickly. The Afterselect is actually being called, and the second Messagebox ( when selecting a child ) comes up correctly .. but the first one isn't. Selecting a child with my code works fine, but not the parent. To me , that doesn't make sense, as it really checks if the parent is selected or not, or else it wouldn't make it to the else section and show the child messagebox.

Rick

Christian Graus7-Feb-08 13:14

7-Feb-08 13:14

Obviously this means the check is not doing what you expect it to. So, set a break point and look at the properties of the event args. As I said, I think that checking if the selected node has children looks like the easiest way to do what you're after.

Rick van Woudenberg7-Feb-08 13:22

7-Feb-08 13:22

Christian ,

I guess your right. I changed a bit in my code , and now it works fine :"

private void treeView_AfterSelect(object sender, TreeViewEventArgs e)<br />
{<br />
    if (e.Node.Level == 0)<br />
        ClearAll();<br />
    else<br />
        FillDaTree();<br />
}

I'm very curious to know what the diff is between e.Node.Parent.IsSelected and e.Node.Level == 0

Cheers,

Rick

Rick van Woudenberg7-Feb-08 13:26

7-Feb-08 13:26

Well,

I do know that difference as e.Node.Parent.IsSelected would only go up until it reached the parent of the child node, which could several levels deep, while e.Node.Level == 0 would got to the actual root node at level 0. But in a treeview with a parent at level 0 , and a child at level 1 , should just work.

object or struct naming based on string variable

Alan N8-Feb-08 2:07

Alan N

8-Feb-08 2:07

Hi Rick

if (e.Node.Parent.IsSelected)
{
MessageBox.Show("This is the parent node");
}

This piece of code doesn't make sense in the context of an AfterSelect handler. By definition e.Node is selected therefore it's parent, e.Node.Parent, is not and e.Node.Parent.Selected will always be false.

AlanN

tokyostormdrain7-Feb-08 12:45

tokyostormdrain

7-Feb-08 12:45

Hi,

I'm quite new to c# and OOP in general.
I have a situation where I am parsing an xml file and creating objects based on what I find there. What I want to do is name any object or struct I create using the name attribute from my element. I have assigned the current name attribute to a string variable. How do I know use that to name my object to the value of that string?

Thanks for any help.

Neil

tsd

Re: object or struct naming based on string variable

Guffa7-Feb-08 13:01

Guffa

7-Feb-08 13:01

You can't do that, and even if you could, how would you use a variable that you don't know exists?

Use a collection to store your objects, like:

// create a dictionary
Dictionary<string, MyClass> items = new Dictionary<string, MyClass>();
// add an item to it
items.Add(name, new MyClass(something));
// get an item from it
MyClass item = items[name];

Experience is the sum of all the mistakes you have done.

passing arrays as arguments in C#

Xarzu7-Feb-08 11:46

Xarzu

7-Feb-08 11:46

Here is a simple question for you C# Gods. How do you pass arrays -- specifically, an array of integers of unknown length -- as arguments to methods in C#?

pmarfleet7-Feb-08 11:49

pmarfleet

7-Feb-08 11:49

Xarzu wrote:
How do you pass arrays -- specifically, an array of integers of unknown length -- as arguments to methods in C#?

Use the params keyword.

Paul Marfleet

"No, his mind is not for rent
To any God or government"
Tom Sawyer - Rush

Christian Graus7-Feb-08 12:04

7-Feb-08 12:04

Why can't you just pass an int[] ? Personally, I'd use a List<int>

Eslam Afifi7-Feb-08 12:04

Eslam Afifi

7-Feb-08 12:04

Just do something like

void MyFunction(int[] myarray)
{ }

and call it like this

int[] arr = {2,4,6};
MyFunction(arr);

You can also use the params keyword which allow you to pass the elements as parameter as well as the former way.
Let's say something like

void MyFunction(params int[] myarray)
{ }

call it either

int[] arr = {2,4,6};
MyFunction(arr);

MyFunction(2,4,6);

Guffa7-Feb-08 12:05

Guffa

7-Feb-08 12:05

An array is just an ordinary object. Just pass the reference:

int[] someArray = new int[] { 1, 2, 3 };
someMethod(someArray);

public void someMethod(int[] arrayArgument) {
   Console.WriteLine(arrayArgument.Length.ToString());
}

Experience is the sum of all the mistakes you have done.

Bitwise masking - What's wrong with this code? [SOLVED]

Ravenet7-Feb-08 16:17

Ravenet

7-Feb-08 16:17

Hi Guy

last two replay are cleared your question.

that's correct way.

Thanks

Cheers
RRave
MCTS,MCPD

#realJSOP7-Feb-08 10:01

#realJSOP

7-Feb-08 10:01

I have the following code:

if ( (m_myThread.ThreadState & System.Threading.ThreadState.Running) == 0)
{
	DoSomething();
}
else
{
	DoSomethingElse();
}

The code above results in the compiler claiming that the code in the else block is unreachable. if I change the if line to this:

if ( m_myThread.ThreadState & System.Threading.ThreadState.Running == 0)

I get the following compiler *error*:

Operator '&' cannot be applied to operands of type 'System.Threading.ThreadState' and 'bool'

What's going on (in both cases)?

"Why don't you tie a kerosene-soaked rag around your ankles so the ants won't climb up and eat your candy ass..." - Dale Earnhardt, 1997
-----
"...the staggering layers of obscenity in your statement make it a work of art on so many levels." - Jason Jystad, 10/26/2001

modified on Friday, February 8, 2008 5:16 AM

led mike7-Feb-08 10:07

led mike

7-Feb-08 10:07

John Simmons / outlaw programmer wrote:
What's going on (in both cases)?

Operator Precedence

led mike

Christian Graus7-Feb-08 10:08

7-Feb-08 10:08

The code you're using is straight out of MSDN, so I don't see why it shouldn't work. What if you break it down and use the debugger to see what the result is ? I mean, what if you & the two values into a variable first, then check it's value ? That way you can have a look at what is going on.

I'd also try swapping it around to this:

if ( (m_myThread.ThreadState & System.Threading.ThreadState.Running) == System.Threading.ThreadState.Running)

and then swap the two method calls, obviously.

John Simmons / outlaw programmer wrote:
I get the following compiler *error*:

In the second case it's an order of operations error, the == has precedence, so it works out to

if ( m_myThread.ThreadState & (System.Threading.ThreadState.Running == 0))

#realJSOP7-Feb-08 10:18

#realJSOP

7-Feb-08 10:18

Actually, according to MSDN, Running is 0, so if you want to check for ThreadState.Running, you have to do it like this:

if ((myThread.ThreadState & (System.Threading.ThreadState.Stopped | System.Threading.ThreadState.Unstarted)) != 0)

modified on Friday, February 8, 2008 5:16 AM

Christian Graus7-Feb-08 11:25