why qstringlist *ps "Segmentation fault"?

[lanmanck]

i want to init QStringList through a function,
my code:

QStringList qs;
initqstringlist(&qs);
 
the func is:
int void initqstringlist(QStringList *qs)
{
   qs->append("1");  //Segmentation fault
   qs->append("2");
}

QStringList qs;
initqstringlist(&qs);

the func is:
int void initqstringlist(QStringList *qs)
{
   qs->append("1");  //Segmentation fault
   qs->append("2");
}

To copy to clipboard, switch view to plain text mode 

why it report "Segmentation fault"? do i misunderstand the class?