understanding code in c++

Question

This question arose while studying NS-3 codes. There is a for loop as below

enter code here

for (NetDeviceContainer::Iterator i = periDevice.Begin ();
                                i != periDevice.End ();
                                i++)
{
  (*i)->GetObject<BleNetDevice> ()->GetLinkLayer ()->SetAdvInterval (Time("1s"));

  (*i)->GetObject<BleNetDevice> ()->GetLinkLayer ()->SetRole (BleLinkLayer::ADVERTISER);
  (*i)->GetObject<BleNetDevice> ()->GetLinkLayer ()->SetAdvMode (BleLinkLayer::GENERAL_ADV);
}

What is the meaning of above code?
What is Iterator ? What is (*i)->xxx ?

Which c++ concept is used here.

Thank you in advance.

Refer to [what I told you yesterday](http://stackoverflow.com/questions/40485692/ptrnode-a-createobject-node#comment68215436_40485692) — StoryTeller - Unslander Monica, Nov 09 '16 at 09:50
You can read about iterators in any [decent book](http://stackoverflow.com/questions/388242/the-definitive-c-book-guide-and-list) or on [stackoverflow](http://stackoverflow.com/documentation/c%2b%2b/473/iterators). — molbdnilo, Nov 09 '16 at 09:52
Its hard to sit and learn everything in c++ and then start working on my project. Do you suggest any other better method? — spectre, Nov 09 '16 at 09:52
@spectre, I won't attempt open heart surgery before going to med school. — StoryTeller - Unslander Monica, Nov 09 '16 at 09:53
haha, ok.fine. How much time do you think it takes someone with basic knowledge in c++ to understand concepts such as this ? — spectre, Nov 09 '16 at 09:55
Iterators are used quite heavily in the standard library, and chained calls should be covered fairly early in any decent book. So I suggest you focus on that in your book. — StoryTeller - Unslander Monica, Nov 09 '16 at 09:57

score 1 · Answer 1 · answered Nov 09 '16 at 10:03

What is the meaning of above code?

It is a for loop over the objects in the periDevice container, calling the listed functions on each object.

What is Iterator ?

Iterator is a C++ concept (not an C++ exclusive concept) allowing one to iterate over collections. A collection in this context is a data-structure holding multiple objects of the same time (a NetDeviceContainer in your case).

For every iteration of the for loop, the iterator points to one object in the collection.

Some more details here: http://www.cplusplus.com/reference/iterator/

What is (*i)->xxx ?

i is an iterator. Assuming the iterator follows the usual standards, the * is overloaded and returns a reference to the containing object. This object seems to be of some type, for which the -> is defined (most likely a pointer) allowing you to access the "GetObject" function.

Which c++ concept is used here.

Difficult to say, what counts as a c++ concept. I would say:

for loops
Iterators
Pointers
Operator Overloading
Templates

thanks a lot for the answer. – spectre Nov 09 '16 at 10:08 — spectre, Nov 09 '16 at 10:08

understanding code in c++

1 Answers1