Threadiing - C# Discussion Boards

7-Aug-07 0:27

Hello developers,
Does anybody know a good e-link to Threading tutorial for windows application in C#.Net.
Please make sure i am looking for windows application and not console because i could already see many for console.
But i cant find good article for windows application. I am looking for such article which takes me from beginner to advance level threading for windows application only.

Thanx Smile | :)

James

Christian Graus7-Aug-07 0:42

Christian Graus

7-Aug-07 0:42

they work exactly the same in both instances.

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 )

james_dixon_20087-Aug-07 1:28

7-Aug-07 1:28

Do they ?
But i tried one example and it didn't work fine on windows but works fine over console. I think their is a lil difference. May be not much but i need to know that difference. Ok ill look again over some console applications. Lets see if it works..

Tristan Rhodes7-Aug-07 2:04

Tristan Rhodes

7-Aug-07 2:04

Hi James,

Only the thread a Form is created on can manipulate the form and it's child controls. Trying to set properties on controls from a worker process will throw an exception.
You would have to use the Invoke() method and send a delegate to the form that will be run on the controlling thread. Besides that they work pretty much the same.

T

-------------------------------

Carrier Bags - 21st Century Tumbleweed.

james_dixon_20087-Aug-07 3:00

7-Aug-07 3:00

Yeh you are right. Just have a look in what i did. Its working but i want to know if there is any other better approach..

<br />
private void Startbtn_Click(Object sender, EventArgs e)<br />
{<br />
  Thread t = new Thread(new ThreadStart(try));<br />
  t.Start()<br />
}<br />
<br />
void try()<br />
{<br />
  int count = 0;<br />
  while (true)<br />
  {<br />
    if(count > 1000)<br />
    {<br />
      break;<br />
    }<br />
    Thread.Sleep(1000);<br />
    if(InvokeRequired)<br />
    Invoke(new new_try_delegate(new_try));<br />
    count++;<br />
  }<br />
}<br />
<br />
 public delegate void new_try_delegate();<br />
<br />
 void new_try()<br />
 {<br />
  textBox1.Text += "This is new Thread" + Environment.NewLine;<br />
 }<br />
<br />
<br />

Now the above code just repeat the message "This is new Thread" for 1000 times and it works fine. But now my questions are:---

1.] Can i use same delegate call i.e. public delegate voud new_try_delegate() for all different threads i create.

And does it work the same way if i am writing data into textbox from different location of my application.

Lastly can you suggest me some more options to test so that i understand it better.

Cheers Smile | :)

pbraun7-Aug-07 4:44

pbraun

7-Aug-07 4:44

I see some problems in your code.

1. What happens when you hit the start button a few times without waiting for the thread to finish.

2. Invoking the delegate from the thread does work from your thread, but this method requires that each object calling to the new_try() method know about the delegate and call that.

3. If the new_try() method is called from any other thread than the GUI thread, it will take time to execute the call.

The new_try() method should take the form of

public delegate void new_try_delegate();
new_try_delegate newTryEvent = new new_try_delegate(new_try);

public void new_try()
{
   if (this.InvokeRequired)
   {
      Invoke.Begin( newTryEvent );
   }
   else
   {
      textBox1.Text += "This is new Thread" + Environment.NewLine;
   }
}

Now you can call new_try() from any other thread and the GUI thread will do the work of displaying the string.

As for the first problem, you should always check to see if the thread is running before starting another instance of that thread so that the user doesn't run themselves out of resources.

Phil

Tristan Rhodes7-Aug-07 5:00

Tristan Rhodes

7-Aug-07 5:00

That's a nice way of doing it. Didn't know about the InvokeRequired property. Smile | :)

-------------------------------

Carrier Bags - 21st Century Tumbleweed.

james_dixon_20087-Aug-07 6:40

7-Aug-07 6:40

okay... thanks for pointing that out.
Smile | :)

Tristan Rhodes7-Aug-07 4:46

Tristan Rhodes

7-Aug-07 4:46

Threads are mind bending to get your head round when you get into them. Took me ages to figure them out.

You already know a delegate is a function pointer, and as long as it isn't executed by a worker thread, and is instead processed by the Main thread, it will be thread safe and valid for UI manipulation. You can create as many instances of delegates pointing to the same function as you like, and simply run them on the main thread.

Try spawning multiple threads and firing off delegates for the same function with different fields. The invoke method lets you supply a parameter list after the delegate so you can supply arguments to the invoked function.

Also, you could experiment with.. i think it's Anonymous Methods, where you create the method body with the delegate declaration.

Good luck

T

-------------------------------

Carrier Bags - 21st Century Tumbleweed.

Default program of file.

Rahul.RK7-Aug-07 0:26

Rahul.RK

7-Aug-07 0:26

Hello friends,

can we get default program of file specified.

E.g. default program for .mp3 file may be windows media player/winamp like that.

Is there any method which gives such details of default program.

thanks in advance.

Rahul Kulkarni

Christian Graus7-Aug-07 0:44

Christian Graus

7-Aug-07 0:44

You get that info via the registry, I don't know of a method that will look it up for you, however.

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 )

Tormod Fjeldskaar7-Aug-07 0:49

Tormod Fjeldskaar

7-Aug-07 0:49

To see how this information is stored in the registry, you may want to read what Microsoft has to say about file types[^].

Vasudevan Deepak Kumar7-Aug-07 0:49

Vasudevan Deepak Kumar

7-Aug-07 0:49

This page (http://msdn2.microsoft.com/en-us/library/aa969375.aspx[^]) describes the keys used.

Vasudevan Deepak Kumar
Personal Homepage
Tech Gossips

Tormod Fjeldskaar7-Aug-07 1:16

Tormod Fjeldskaar

7-Aug-07 1:16

I can't see that it does. The page you point to describes how the Default Programs API works, i.e. how to tell windows the capabilities of a certain application.

Kumar Arun7-Aug-07 1:36

Kumar Arun

7-Aug-07 1:36

MyComputer\HKey_Classes_Root\AudioCD\Shell\Play\Command

Check it

Arun Kr

Hessam Jalali7-Aug-07 1:47

Hessam Jalali

7-Aug-07 1:47

as I know it can be retrieved with shell32 FindExecutable API
but sometimes the results is not like what is Expected

Maybe this going to help

<code>

    class Shell32Utils
    {
        const int FILENOASSOCIATED = 31;
        const int FILENOTFOUND = 2;
        const int PATHNOTFOUND = 3;
        const int SUCCESS = 32; //and longer
        const int BADFORMAT = 11;

        

        [DllImport("shell32", EntryPoint = "FindExecutable")]
        static extern int FindExecutable(string file, string directory, [MarshalAs(UnmanagedType.LPStr)] StringBuilder result);


        public static string Find(string file)
        {
            string fileName=System.IO.Path.GetFileName(file);
            string filePath = System.IO.Path.GetDirectoryName(file)+"\\";

            System.Text.StringBuilder res = new StringBuilder(1024);

            int stat = FindExecutable(fileName, filePath,  res);

            switch (stat)
            {
                case FILENOASSOCIATED: throw new Exception("File Not Associated");
                case FILENOTFOUND: throw new Exception("FileNot Found");

                case PATHNOTFOUND: throw new Exception("Path not Found");

                case BADFORMAT: throw new Exception("Bad Format");

                default: if (stat >= SUCCESS) return res.ToString();
                    else throw new Exception("Unknown Error");
            }
        }       
    }

</code>

good luck