How to kill and rerun the main process in qt? - c++

Question

I have an app which can run another exe files. Some buttons and connect to the executeable files. When i click the button, start running the another program... this is good, but remains open the main window and the program still running. I want to achive that the main window stop running (or disapear) when another program is running, and when i exit from the other app, run (or appear and run) the main process.
I tried this:
void MainWindow::RunSys(QString sh)
{
this->close();
QProcess ps;
if(ps.execute(sh)<0)
{
QMessageBox messageBox;
messageBox.critical(nullptr,"Error",sh + "Error!");
}
this->show();
}
//I call the function this way:
QString sh = settings->value("Run").toString();
connect(pButton, &QToolButton::clicked, [=] { RunSys(sh); });
It's working on Linux. Opens the executable program but the main program is till running on Windows. What can I do?

Answer 1

I could not reproduce the bug, we'll need you to provide a complete, minimal and reproducible example that illustrates the bug.
If it can help you, I've written the following sample code based on yours:
Header
class MainWindow : public QMainWindow
{
Q_OBJECT
protected:
QPushButton * pb;
public:
MainWindow();
void runShellCmd(const QString & cmd);
};
Implementation
MainWindow::MainWindow()
{
// Build the main window
resize(600, 400);
pb = new QPushButton("run cmd", this);
this->setCentralWidget(pb);
// Create the command
QString cmd("ping 127.0.0.1 -n 6");
// Connect the signal
connect(pb, &QPushButton::clicked, [=](){runShellCmd(cmd);});
}
void MainWindow::runShellCmd(const QString & cmd)
{
QProcess ps;
this->close();
int exit_code = ps.execute(cmd);
switch(exit_code)
{
// Do what you want with exit code
default:;
}
this->show();
}
Main function
int main(int argc, char ** argv)
{
QApplication app(argc, argv);
MainWindow w;
w.show();
return app.exec();
}
And it worked fine.
EDIT:
I have understood what's wrong. Your example with calc.exe has whispered me the issue :)
Actually, QProcess::execute() blocks until the command call returns. In this case, it returns right after the launch, not when the windows is closed. So you got the expected behaviour.
I'm afraid that it will be way much harder to do it this way. Because calc.exe being an external program, except if you can read kind of closing signal from an external program, you would not be able to detect when it is closed.