Threading issue in csharp

Question

1.00/5 (1 vote)

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I have file copy program in which start button cause to start the thread and cancel button causes cancel operation.

C#

 public class Form
{
private bool bCancelFlag = false;
onStartCopying()
{
  if(btnText.equals("Start"))
  {
      bCancelFlag = false;
      btnText.Text = "cancel";
      Thread th = new Thread(new ThreadStart(startThread));
      th.start();
  }
  if(btnText.equals("cancel"))
  {
    bCancelFlag = true;
    btnText.Text = "Start";
  }
}
startThread()
{
  while(fileLength)
  {
    value = value + 1;
    reportProgress(value);
    if(bCancelflag)
    {
      break;
    }
  }
 reportProgress(int value)
 {
   progressBar1.BeginInvoke((Action)(() =>
   {
        progressBar1.Value = value;
    }));
 }
}
}

When Cancel label appear , we click on it causes label to start and again click on start label causes cancel label and app get hanged.Nothing happen over there.
what is problem.Is it related to thread start and stop??

Posted 14-May-15 20:26pm

Sarita S

Updated 14-May-15 21:38pm

v2

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Comments

Sergey Alexandrovich Kryukov 15-May-15 2:51am

Did you use the debugger? The problem looks simple enough.
Comparison with button text is absolutely dirty.
bCancelFlag declaration is not shown. This cannot be your real code. You need to paste exact code.
So, please use "Improve question".
—SA

Sarita S 15-May-15 3:51am

yes I used debugger.Everything is going fine.Only App is get hanged on cancel to start operation

Harshad Kathiriya 15-May-15 5:26am

It may be cause an issue related to Start and Stop Thread.
As per your code, you have started the thread but not stopped it.

revise your code.

Sarita S 15-May-15 5:41am

After coming out of while thread get stopped. or on Cancel button click It get out of while loop causes to end thread.

1 solution

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CPallini · Answer 1 · 2015-05-14T20:50:00

Solution 1

You missed and else:

C#

if(btnText.equals("Start"))
 {
   // ...
 }
 else if (btnText.equals("cancel"))
 {
   // ...
 }

Posted 14-May-15 20:50pm

CPallini

Comments

Sergey Alexandrovich Kryukov 15-May-15 3:19am

It would not fix anything, isn't it obvious? The whole "technique" is quite dirty.
—SA

CPallini 15-May-15 3:32am

I don't comment about the technique. Anyway, missing the else is just a programming error.

Sarita S 15-May-15 3:38am

Program dont have else part.

CPallini 15-May-15 3:45am

It should have. Suppose button text is "Start", then the first if-block is executed and button text becomes "cancel", this causes (in your code) immediate (unintended, I hope) execution of the second if-block.

Sergey Alexandrovich Kryukov 15-May-15 8:58am

Of course. I did not look at assignment to "cancel" in first part. 5ed.
But anyway, this will be too dirty to be correct. :-)
—SA

CPallini 15-May-15 13:37pm

I have to agree. :-)
By the way, thank you.

Sergey Alexandrovich Kryukov 15-May-15 13:39pm

:-)