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i got a realy strange issue with invoking code on a multi threaded application , it happens on thins function below:
<br />
private void closeForm()<br />
{<br />
if (this.InvokeRequired)<br />
{<br />
ShowFormCallback d = new ShowFormCallback(closeForm);<br />
this.Invoke(d, new object[] {});<br />
}<br />
else<br />
{<br />
try<br />
{<br />
goform.Close();<br />
}<br />
catch(Exception e)<br />
{ <br />
Console.WriteLine("Cant close the damn form " + e.Message);<br />
}<br />
}<br />
<br />
}<br />
<br />
}<br />
The Error is:
"Cross-thread operation not valid: Control 'player2' accessed from a thread other than the thread it was created on."
although on debug i see that when the closeForm() is executed
this.InvokeRequired has a "false" value.
and yet when the line: "goform1.Close();" is executed i get cross-thread operation not valid.
how is this possible, i have used this technique (given by the MSDN) in order to avoid such errors several times and never had problem with it,
so what could be the cause of such a thing?
Net
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What does "goform.InvokeRequired" return? That is the control you are executing a method on, so it's really up to that control to determine if it needs an invoke.
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oh oops , my mistake  , i wrote this.InvokeRequired instead of ,
goform.InvokeRequired , now it returns 'true'
Net
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Can Fibonacci Series be generated with the help of operator overloading?
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It would for exampel be possible to make a class representing a number in the fibonacci series and overload for example ++ to give the next number in the series.
I can't think of any reason this should be done, but as long as the question is if it could be done, then the answer is yes.
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Sure - it could even be done with anonymous methods if you like. However, wouldn't it have been better for you to actually try it out before posting a question? That would have answered it for you - and you'd have advanced your coding skills just that little bit more.
Deja View - the feeling that you've seen this post before.
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It's possible, but certainly not practical.
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Hi all,
Library is coded in C#.
Here are the conditions:
So if I've got an array list of MyObjects_;
Each MyObject_ contains a value
There are only 4 types of MyObjects_ (Ie. obj1 = 6, obj2 = 4, obj3 = 3, obj2 = 2, obj1 = 1);
I have an input value of (MyObjects_)input_ = 21;
The array list size is unsorted and is an undetermined size until runtime.
What's the logic to determine the most accurate combination of objects to result in the combination of (obj[i] == input_)?
Thanks in advance
Humble
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Just looking for the logic, and not the code.
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humblepgmr wrote: So if I've got an array list of MyObjects_;
What's the deal with the underscore?
humblepgmr wrote: There are only 4 types of MyObjects_ (Ie. obj1 = 6, obj2 = 4, obj3 = 3, obj2 = 2, obj1 = 1);
What do you mean by "type" in this case?
humblepgmr wrote: What's the logic to determine the most accurate combination of objects to result in the combination of (obj[i] == input_)?
Could you specify in what way any combination would be more accurate than any other?
---
single minded; short sighted; long gone;
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1) How does an input value of 21 fit into a context of an array list containing 4 different types, none of which are 21?
2) What is an "accurate combination of objects"?
3) What is now i in the "obj[i] == input_" part? And index I guess... but of what?
4) What is that trailing underscore doing everywhere (not relevant for your question as such I guess, just wondering).
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Hi,
I have dug through MSDN regarding using a destrutor and Dispose method.. Now I am confused, whats the difference between the two.. They both can be used to release unmanaged resources, right? So whats the difference?
Regards,
Blumen
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In c# there's no such thing as a deterministic destructor like in c++. Instead you have a non-deterministic finaliser. If you include a finaliser in your class, when you have finished with the object it will be placed in the finalisation queue, and the finailise method will get called next time garbage collection is run.
This means that your objects may hang around for quite a while, hogging up memory, or holding onto resources, so to help things along we use the dispose pattern which allows us to ensure that objects gets cleared up quickly and finislisation doesn't have to happen. The dispose method should clean up all resourses, and supress finalisation, while the finaliser method should only clear up _unmanaged_ resources. This is becuase the finaliser may get called much later on, so other managaed resources may already have been destoryed, so you mustn't risk referencing them again.
You can then call the dispose method manually when you have finished with the object (or use the "Using" keyword to ensure it gets called)
To read about the dispose pattern check out this site:
http://msdn2.microsoft.com/en-us/library/b1yfkh5e.aspx
See this page for more about the "Using" keyword
http://msdn2.microsoft.com/en-us/library/yh598w02.aspx
Hope that helps.
Simon
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Thanks alot Simon, that was very useful.
So I conclude that:
1. Finalize method should be used to clear up only unmanaged resources, whereas Dispose method can be used to clearup any object that I create.
Using keyword is very helpful here.
2. We are unable to predict when Finalize would be called and executed by GC, where as Dispose method would be called as soon as the object is out of scope, right?
Regards,
Blumen
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blumenhause wrote: Finalize method should be used to clear up only unmanaged resources
Dispose should be used to clean up resources. A finalizer can be used as a backup when implementing the IDisposable interface, but then it's never really meant to be used as the Dispose method should suppress the finalizer.
A finalizer is not guaranteed to be executed. A background thread executes the finalizers in the finalization queue. If the finalizers left in the queue take too long to run when the application ends, the rest of the objects are just thrown away without finalizing.
blumenhause wrote: where as Dispose method would be called as soon as the object is out of scope
No. The Dispose method is never called automatically. You have to call it explicitly, or use a using block that will call it.
As you always call it explicitly, you always know when it's called.
---
single minded; short sighted; long gone;
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You can also take a look at this article: http://www.codeproject.com/useritems/idisposable.asp[^]
Finalizers are expensive to use in that they are difficult to write properly and add an additional memory cost to your finalizable object. Any time a finalizable object is created it is placed in a special queue that must be checked each time the garbage collection cycle runs. This happens even if you never actually use the object.
The best approach is to implement the IDisposable interface and the Dispose pattern properly, and only implement a finalizer when absolutely necessary.
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Hai Everybody,
I am having a tree view in that the nodes are in a hierarchical manner.
The nodes are checkable.
Now when some child nodes are not selected, then I have to make the parent node check box to have the check state "Indeterminate".
But there is no Check State property of the tree node.
Then i tried to convert it as a check box in code, but it is giving the error indicating that it is not possible.
Can any one give me the solution for this?
Best Regards,
M. J. Jaya Chitra
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Try this: Turn the treeviews checkboxes property _false_ and instead create an ImageList and set the treeviews stateimagelist to the imagelist. You can then create three images in the image list (checked/unchecked/intermediate), and use the nodes stateimageindex (or stateimagekey) to set the state image.
Let me know if it works for you, I've never done this before 
Simon
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pls, who anyone help me!
I am writting a program to log my PC in a txt file.
when any one start PC it log to txt file and he shutdown it log the txt file.
Thanks
Help you, hepl me
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One hacky type way to stop / slow windows from shutting down, is to show a MessageBox. So, in your apps onClose event (ie. Windows is trying to close your app for shutdown) show a message box while you make your log, then close it.
My current favourite word is: Waffle
Cheese is still good though.
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Hi  greetings to all [![Rose | [Rose]](https://codeproject.global.ssl.fastly.net/script/Forums/Images/rose.gif) ];
I am working on a client-Server Project.... (C#.net/SQL)
Need to know ::
1. how can i start the Client(.net) application(s) on a LAN from server application(.net)
2. How to run a particular service(Windows) on the client machine from server (which in turn can communicate with the already running client application)
Thanks n Regards,
Aamu
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hi , Thanks in advance for everyone who reads that!
How can i set a thread so that when i start it the calling thread returns to what it did before and the new thread continues from that point , or any other solution with similar effect ?
for example:
<br />
<br />
public void Some_Event(Object sender , EventArge e)<br />
{<br />
Console.writeline("Im the Old Thread: {0}",Thread.CurrentThread.Name);<br />
<br />
Console.writeline("Im the new Thread: {0}",Thread.CurrentThread.Name);<br />
<br />
SomeForm sf = new SomeForm(((String)sender).username);<br />
<br />
}<br />
<br />
Net
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Google finds this.[^]
You might also want to look at the TreadPool class (Google it). It provides a bit less control over the treads, but in returns handles queuing requets, creating threads etc automatically.
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, if u force then u can do !!! but not recomanded !!!!
in VB6 and Dispose() in C# 
method.