QList of a QList

[been_1990]

Why am I not able to create a QList of QList's?
Ex:

QList<QList> * tileList;
Error:
type/value mismatch at argument 1 in template parameter list for 'template<class T> class QList'
expected a type, got 'QList'

[tbscope]

Every QList requires a type, so also the second one.

[been_1990]

Every QList requires a type, so also the second one.
What do you mean by that?

[Zlatomir]

He meant something like this:
QList<QList<some_type> > list; // notice the space within '>' and '>'

[been_1990]

He meant something like this:
QList<QList<some_type> > list; // notice the space within '>' and '>'

Ok, but how can I add a QList?
Ex:

QList< QList<int> > * tileList;

QList<int> list;

tileList << list;

Gives an error:

error: no match for 'operator<<' in '((Widget*)this)->Widget::tileList << rowList'

note: candidates are: QDataStream& operator<<(QDataStream&, const QChar&)
//Huge list follows.....

Edit: If I use:

tileList->append(rowList);
The application crashes with "Invalid parameter passed to C runtime function.
Invalid parameter passed to C runtime function."

[SixDegrees]

That's because your list of lists is actually a pointer to a list of lists - a pointer which you never allocate or initialize. Lose the '*'.

[Zlatomir]

Or use something like:

QList<QList<int> > *list = new QList<QList<int> >;
if you really need it on the heap.

And read a little about pointers, if you have int *p; you can't legally use p because it points to an unspecified location.

You need an object and a pointer, something like:
int number = 10; int *p = &number;
or use the pointer to create an object on the heap (that object doesn't have a name, but it is there):
int *p = new int(10);

[been_1990]

You are right. I forgot. Thanks for the lesson. :)