Re: strange problem with const char *

I have problem with conversion from QString to const char * , I know that it's not the right newsgroup but I don't know if is a c++ issue problem.

int main(int argc, char *argv[])
{
     QApplication a(argc, argv);
     QString str("ciao");
     const char * xxx=str.toLatin1().constData();
     _file(str.toLatin1().constData());
     _file(xxx);
     MainWindow w;
     w.show();

     return a.exec();
}

at the first call "_file(str.toLatin1().constData())" the debugger show that the parameter passed to function _file have the correct value while in the last call _file(xxx) the parameters passed to _file function is incorrect. I didn't understand why?