Re: strange problem with const char *

=?ISO-8859-1?Q?Marcel_M=FCller?= <>
Wed, 18 Dec 2013 13:02:45 +0100
Am 18.12.2013 11:28, schrieb alessio211734:

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();
     MainWindow w;;

     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?

Whatever QString is, read the documentation of QString. Especially the
point how long the storage retuned by constData() remains valid.

Most likely you have undefined behavior because of a dangling reference,
because you passed a temporary to xxx and access it after the QString
instance, that provides the storage has been destroyed.


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