[Qt-interest] QDialog::exec VS QDialog::show

[Nikos Chantziaras]

On 05/06/2010 02:20 AM, yifli at mtu.edu wrote:
> Hi,
>
> What's the difference between the two functions?
>
> I created a dialog, which is supposed to show up when necessary later on.
>
> However, my program seems to like QDialog:exec() better, which brings the
> above question

With exec(), you can't interact with the dialog's parent or with the 
rest of the application if it's parentless; it can't never get focus and 
all input gets blocked.  This kind of window is called "modal".

With show(), you can still use the parent window.

Which one you choose depends on the dialog's function.  If you need to 
block interaction with the dialog's parent or the whole application, you 
use exec().  Otherwise, show().  show() can have some complications, 
like being able to launch the same dialog multiple times which might not 
be what you want.  In those cases, instead of creating another dialog, 
you can just shift focus to it and raise it instead.