Application stops working unexpectedly

Hi,

in my app I am reading a file name by opening a QFileDialog and save the filename to a string variable. And then I check for the variable in question of filename returned. I am doing this with an If statement and showing message box if the variable is empty. But when I get to the If statement my program showing a message that "example.exe has stopped working unexpectedly". here is my code

Code:

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void MainWindow::getFilename()
{
    QMessageBox msgbox;
    msgbox.setText("Please select the file");
    filepath = QFileDialog::getOpenFileName(this, tr("Open File"),"/home",tr("Text files(*.txt)"));
  if(filepath.isEmpty())
      msgbox.exec();
}

---

I would be grateful for any solution.

Thank You,
Baluk

run the application in a debugger, and see exactly where it crashes, you will probably also see why (NULL pointer or similar)

oke. I run the app in debug mode and I receive a message that

Quote:

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The inferior stopped because it received a signal from operating system, SignalName : SIGSEGV SiganMeaning:Sigmentation fault

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.
I have removed the above function from my app and I still get this error when I try to close the app by clicking on the "Close" menu item on the top of the window. Can you tell me why is it because if it is a common error.

No - run the app in the debugger - this means you run it from within the debugger - not by double clicking on the exe.
The code you posted should not crash, the problem is somewhere else in your app.

oke. But I run the program from the Qt creator not by clicking the exe file. Unfortunately I have no idea where to look for when debugger shows me some output when I get the error message.

can you post more code?

My app has 200 lines of code. I don't know from which portion the error is. But my program exited with code -1073741819.

Quote:

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Originally Posted by baluk

oke. I run the app in debug mode and I receive a message that
.
I have removed the above function from my app and I still get this error when I try to close the app by clicking on the "Close" menu item on the top of the window. Can you tell me why is it because if it is a common error.

---

When you get this, Creator should show you where the crash occured. There should be a backtrace available so that you can see where it crashes. And forseeing your next question - no, we will not teach you here what backtrace is. If you are a programmer you should either already know that or be able to find it out yourself.

Yes I see the backtrace when I run in the debug mode. The applications crashes at QObjectPrivate::deleteChilderen() function in the qobject.cpp file at line 1978. Can you tell me what it means.

Go back in the trace to the first line you can see which is from your code.

From my code I get the error next after the destructor statement

Quote:

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delete ui;

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. When I press F10 from the statement, I get the segmentation fault message.

you probably forgot to do ui = new <YourUIWidget>;

Post the whole backtrace.

Here I am attaching the image showing the debugger output. I can't see the option to copy the output. And I see the message

Quote:

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Lowest section in C:\Windows\system32\normaliz.dll is .text at 00401000

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in the console after stopping the debugger.

So the crash happens when you are closing the application? Does the program work correctly until then?

yes exactly. the crash happens only when closing the app. Until then every thing works fine. Before It was running fine but when I added the above function my app started crashing. So I then removed the function but still the crash happens when closing the application.

My guess is that you have a double delete somewhere. You are deleting some object explicitly and then MainWindow destructor deletes it again.