Cannot create a QAbstractItemModel::createIndex(r,c),

[tonnot]

I have a function to retrieve data from my model.
I want to call it using row,col (r,c) set by me.

return a_model->data(QAbstractItemModel::createIndex(r,c),Qt::DisplayRole);

return a_model->data(QAbstractItemModel::createIndex(r,c),Qt::DisplayRole);

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Ok, I get
error: cannot call member function 'QModelIndex QAbstractItemModel::createIndex(int, int, void*) const' without object

Any idea ?

[agarny]

Yes, re-read the error message and you might then realise that you cannot just call QAbstractItemModel::createIndex. You need an object of type QAbstractItemModel to call that method...

[wysota]

He won't call it because it's a protected method But that's a completely different issue...

[tonnot]

Maybe I cannot call model::data ????

[agarny]

Maybe I cannot call model::data ????

As Wysota said, it's a protected method, so...

[wysota]

As Wysota said, it's a protected method, so...

But this is irrelevant in this case, the compiler complains about something else. Only when he fixes the current problem the compiler will complain it's a protected method. Which then will lead to a real question - why is this method protected and should it be used in this context. So let's go one step at a time and let tonnot learn by his own mistakes (again).

@tonnot: I would really recommend you take some cash, go to a bookstore, buy some decent book on C++ and read it WITH UNDERSTANDING.

[agarny]

But this is irrelevant in this case, the compiler complains about something else. Only when he fixes the current problem the compiler will complain it's a protected method. Which then will lead to a real question - why is this method protected and should it be used in this context. So let's go one step at a time and let tonnot learn by his own mistakes (again).

You are definitely more patient than I am!

[wysota]

You are definitely more patient than I am!

Not really. I just don't want to go through the same issue in two days when tonnot decides to use a regular method as a static one again. And since we had an argument when I called him an immature programmer, I'm treating him as a matrure programmer now assuming he does know what he is doing and that he indeed does know C++. Maybe finally he will decide he needs help improving his C++ skills.

[agarny]

Not really. I just don't want to go through the same issue in two days when tonnot decides to use a regular method as a static one again.

Let me rephrase then: you are definitely more optimistic than I am!

[wysota]

Or more sarcastic

[tonnot]

Thanks everybody and excuse me for my poor english and my poor c++ knowlegde.
I understand your explanations

And I'm glad to make you more fun with the task of addressing the forum

[wysota]

Just spend an hour a day for two months learning C++ (and I mean learning and not doing tutorials or copying code) and you will stop giving us reasons to answer the way we do.

[changedsoul]

Hello, I know this is an old thread, but I came across this same error message and I will lay this right out up front....I am an inexperienced programmer!!
I know help was not given to the OP because the claim was they had experience and this error suggested otherwise, but if someone could help me(an inexperienced programmer) out, I would greatly appreciate it.

I learn best by trying and failing. Well I tried, and failed, and got this error message. And then, created an object and got the next error, "its protected!!". So Can someone help explain why some times you can use class::method (QString::Number()) and it works, and some times QTreeWidget::itemFromIndex(), you cant?

I have read many C++ books, but they all seem to do the same thing. They start out teaching basics, loops, conditional statements, etc, then touch on classes, and then BAM, your in over your head. This is how you build a car....you take some nuts and bolts, arrange them in a certain order, and BAM you have a car....and your left scratching your head, well how come that nut and bolt went here and not there, and what happened to everything else. (poor example, but I hope it makes sense).

Thanks.

[agarny]

Seriously?! Read the first few paragraphs of:

http://www.cplusplus.com/doc/tutorial/classes/