QMessageBox after qApp->exec();

[MrMNight]

Hellop, i have segmantation fault error. Can i do in Qt something like this:
main.cpp
@
int main(int argc, char** argv)
{
QApplication app(argc, argv);

MainWindow* mainWindow = new MainWindow;
//some code
int rc = app.exec();

delete mainWindow;

if(rc==2)
{
    QMessageBox::critical(NULL, "CriticalError", "something wrong", QMessageBox::Ok | QMessageBox::Default, QMessageBox::Escape);
}
if(rc==3)
{
    QMessageBox::critical(NULL, "CriticalError", "something else wrong", QMessageBox::Ok | QMessageBox::Default, QMessageBox::Escape);
}
return rc;

}@

I want to call qApp->exit(error_code) in my classes, and then all my classes have to destruct and only message box appear and show until user didn't close it. Sorry for my English...

[raven-worx]

no thats not possible. You need to keep the QApplication object alive...

A possible solution for your problem would be to implement a custom method which displays the message box and calls qApp->exit() and maybe set a member that you've closed the app. So you call this method instead of qApp->exit() directly.
Additionally you override closeEvent() handler of your mainwindow and also display a messagebox in there (depending on the member is set or not mentioned before).

[mcosta]

HI,

this code works fine

@
#include "Widget.h"
#include <QApplication>
#include <QMessageBox>

int main(int argc, char *argv[])
{
QApplication a(argc, argv);
Widget *w = new Widget;
w->show();

int result = a.exec();

delete w;
w = 0;

if (0 == result) {
QMessageBox::information(0, QApplication::translate("Main", "Bye"),
QApplication::translate("Main", "Normal Execution"));
}
else {
QMessageBox::critical(0, QApplication::translate("Main", "Bye"),
QApplication::translate("Main", "Wrong Execution %1").arg(result));
}

return result;
}
@

in Widget i call qApp->exit() with different parameters and all works (no crash). Probably there are problem in MainWindow code.

[MrMNight]

thaks, my problem solved by adding EventLoop (:public QEventLoop) inside main loop, outside Eventloop i doing mainWindow->deleteLater() and checking EventLoop exec code
[quote author="raven-worx" date="1372848306"]no thats not possible. You need to keep the QApplication object alive...

A possible solution for your problem would be to implement a custom method which displays the message box and calls qApp->exit() and maybe set a member that you've closed the app. So you call this method instead of qApp->exit() directly.
Additionally you override closeEvent() handler of your mainwindow and also display a messagebox in there (depending on the member is set or not mentioned before).[/quote]

[MrMNight]

you right, your code work fine but i still cant find error in my code...
[quote author="mcosta" date="1372855531"]HI,

this code works fine

@
#include "Widget.h"
#include <QApplication>
#include <QMessageBox>

int main(int argc, char *argv[])
{
QApplication a(argc, argv);
Widget *w = new Widget;
w->show();

int result = a.exec();

delete w;
w = 0;

if (0 == result) {
QMessageBox::information(0, QApplication::translate("Main", "Bye"),
QApplication::translate("Main", "Normal Execution"));
}
else {
QMessageBox::critical(0, QApplication::translate("Main", "Bye"),
QApplication::translate("Main", "Wrong Execution %1").arg(result));
}

return result;
}
@

in Widget i call qApp->exit() with different parameters and all works (no crash). Probably there are problem in MainWindow code.
[/quote]

[MrMNight]

i handled many objects which parent is mainWindow inside main loop...so i fix @delete mainWindow@ to @mainWindow->deleteLater()@ and it works fine for me without additional loop

[SGaist]

Hi,

What do you mean by "handle many objects which parent is mainWindow" ? Are you deleting them yourself ?