Correct way to quit a Qt program

Question

How should I quit a Qt Program  e g when loading a data file  and discovered file corruption  and user need to quit this app or re-initiate data file   Should I    call exit EXIT FAILURE  call QApplication  quit   call QCoreApplication  quit     And difference between  2  and  3

User · Answer

While searching this very question I discovered this example in the documentation.

QPushButton *quitButton = new QPushButton("Quit");
connect(quitButton, &QPushButton::clicked, &app, &QCoreApplication::quit, Qt::QueuedConnection);

Mutatis mutandis for your particular action of course.

Along with this note.

It's good practice to always connect signals to this slot using a QueuedConnection. If a signal connected (non-queued) to this slot is emitted before control enters the main event loop (such as before "int main" calls exec()), the slot has no effect and the application never exits. Using a queued connection ensures that the slot will not be invoked until after control enters the main event loop.

It's common to connect the QGuiApplication::lastWindowClosed() signal to quit()

User · Answer

if you need to close your application from main   you can use this code  int main int argc  char  argv     QApplication app argc  argv       if  QSslSocket  supportsSsl    return app exit 0       return app exec        The program will terminated if OpenSSL is not installed

User · Answer

How to Run App  bool ok   QProcess  startDetached  C   TTEC  CozxyLogger  CozxyLogger exe    qDebug    lt  lt    Run      lt  lt  ok      How to Kill App  system  taskkill  im CozxyLogger exe  f    qDebug    lt  lt   Close     example

User · Answer

If you re using Qt Jambi  this should work   QApplication closeAllWindows

User · Answer

You can call qApp exit     I always use that and never had a problem with it   If you application is a command line application  you might indeed want to return an exit code  It s completely up to you what the code is

User · Answer

QApplication is derived from QCoreApplication and thereby inherits quit   which is a public slot of QCoreApplication  so there is no difference between QApplication  quit   and QCoreApplication  quit     As we can read in the documentation of QCoreApplication  quit   it  tells the application to exit with return code 0  success     If you want to exit because you discovered file corruption then you may not want to exit with return code zero which means success  so you should call QCoreApplication  exit   because you can provide a non-zero returnCode which  by convention  indicates an error   It is important to note that  if the event loop is not running  this function  QCoreApplication  exit    does nothing   so in that case you should call exit EXIT FAILURE

[qt] Correct way to quit a Qt program?

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