On Thursday 08 May 2008, Hubert Figuiere wrote:
> On Wed, 2008-05-07 at 22:09 -0400, Jamiil wrote:
> > const Glib::ustring& jve::Person::getTitle(){
> > switch(title){
> > case Mr: {return "Mr"; }
> > case Mrs: {return "Mrs"; }
> > case Miss: {return "Miss";}
> > case Ms: { return "Ms"; }
> > case Dr: { return "Dr"; }
> > default: {return "None";}
> > }
> > }
> >
> > Glib::ustring msg = person->getTitle(); <<=== this causes an
> > segmentation fault
>
> You are returning a reference to a temporary. Your compiler should have
> told you already with a warning.
Although this is not really a glib/gtkmm issue (it's basic C++) I think it
deserves a bit more explanation than Hubert's correct but terse response.
Your method is declared as returning a reference, because of that ampersand in
the first line. This tells the compiler not to return the whole Glib::ustring
object but only a reference to it. The code then attempts to return one of
several literal strings. But literal strings are not Glib::ustring, they are
char[]. Since the method returns a Glib::ustring& the compiler has to insert
code to first convert the char[] into a Glib::ustring so that it has
something to take the reference of. And it does so by creating a temporary
object on the stack. As soon as it has done so it takes a reference and
returns, and in the process destroys or overwrites the object you've just
returned a reference to.
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