[Qt-interest] Returning arbitrary value with QApplication::exit()

[Pascal Patry]

On Friday 26 June 2009 12:12:17 Diego Schulz wrote:
> Hi all,
>
> I'm wondering if it's correct to return an arbitrary value with
> qApp->exit(). It works as I expect, but I'm not sure if it's completely
> correcto to do what I do.
>
> I'll try to explain a bit,
>
> Suppose a main.cpp like this
>
>
> #include <QtGui/QApplication>
> #include "mainwindow.h"
> #include "common.h"
>
> int main(int argc, char *argv[])
> {
>    int retcode=0;
>
>    do {
>     QApplication a(argc, argv);
>     MainWindow w;
>     retcode = a.exec();
>
>    } while (retcode == RESTART_APPLICATION);
>
>   return retcode;
> }
>
>
> RESTART_APPLICATION is defined in common.h  as
>
>    #define RESTART_APPLICATION 333
>
> 333 is whatever, an arbitrary number.
>
> In a few circumstances, I want the application to be restarted (eg
> database connection lost, etc), so I call
>
>    qApp->exit(RESTART_APPLICATION);
>
>
> Is it correct to use exit()  in this way?

yes, it is correct and you can safely use it...

> Is there something I should be aware if I want to do this?

yes, on some platforms (at least on unix) the exit code will get into a 
logical 'and'. the returned value will be 'status' & 0377. So the exit codes 
are possible between 0 and 255 inclusively. If you strictly use your constant 
inside your own application, you don't have to bother with this.