C++ Gurus

Thank you for the clarification.

Moved to the C++ Gurus forum, this has nothing to do with Qt.

See the C++ FAQ "How to mix C and C++":http://www.parashift.com/c++-faq-lite/mixing-c-and-cpp.html and search the forums, the topic has been discussed several times. If you have a concrete problem, post some snippets. You cannot get more than a general answer for a general question...

Me too I'm fighting with customer in these days. They have always great ideas :) Seems very experts in mobile development...

You have that List<B extends A> in C++ too, you can put all A subclass types into the list, but if you have B extending A you cannot assign a List<B> to a variable of type List<A>. Both are different cases.

What you've tried does not work in Java either, the following snippet yields an error:

@
public InheritanceTest() {
ArrayList<String> sl = new ArrayList<String>();
String x = "abc";
sl.add(x);

ArrayList&lt;Object&gt; ol = new ArrayList&lt;Object&gt;(); Integer z = new Integer(1); ol.add(z); ol = sl;

}

// Error on the last line:
// Type mismatch: cannot convert from ArrayList<String> to ArrayList<Object>
@

Andre (and everyone else)-

Thanks for your help. The first option compiled correctly. Having seen something that works I hope I can figure it out from here.

Your last suggestion is appropriate. However, I have a large stack of books on C++ programming. The problem is the definition of the word "good". I learned chemical thermodynamics by using a large stack of textbooks. None of them were particulary good. But, where one authors explanation failed another author provided a more thorough explanation. I was able to piece it together that way. I haven't found that approach to work well for understanding C++.

geniale (italian). thank you! =)

[quote author="mlong" date="1315319006"]The most sound advice I can give to you, Iama Hummingbird, is to go read code. (...)
[/quote]
Sound advice indeed.

I just want to add that if you create your object like this
[quote author="Iama Hummingbird" date="1314911566"]
@
A::A():
b(B()),
c(C()),
d(new D()){
}
@
[/quote]
you most probably will have to add a destructor which deletes the object d points to.

If A a is deleted all the member variables are "deleted" automatically, this is b, c, and d*, but not the object d* is pointing to.

The problem is that that QFile usage is a little "abuse" -- QFile is meant for random-access "ordinary" files, not sequential special files. Apart from that, you can just us it like that (possibly using QIODevice::Unbuffered), or since you can assume you're under unix, skip QFile and just use the low-level open(2) and read(2).

Ok, It was so simple! Thanks

Good to see you fixed it. I do wonder why the context doesn't seem to be thread specific, though.

I've moved this to the C++ Gurus' forum, it's not Qt specific.

Regarding the actual question, just follow the advice in the C++ FAQ on the link that EDIS already posted.

Also have a look at "this older thread":http://developer.qt.nokia.com/forums/viewthread/8057 regarding the same topic.

Nice one!

Welcome.

The point why I wrote that comment is, that a pointer can be invalid (which is typically 0), a reference should never be invalid. It should always reference a valid object.

thanks i will mark it as solved

D'oh - need more coffee.

That worked!

-thanks

[quote author="Giorgos Tsiapaliwkas" date="1313091362"]
[quote author="Lukas Geyer" date="1313089715"]
No, you never ever call delete on the object which is currently destructed.[/quote]

if i have this ...[/quote]

You are of course allowed to create and delete objects within a destructor - but you should never delete yourself (delete this). See mlong's post.