What kind of iterators supports random access but not contiguous storage in C++?

Question

I saw that there is a new iterator since C++17,below listed by a screenshot in cppreference. I was a lot confused. What kind of iterators is random access but not contiguous storage in C++?? otherwise, the ContiguousIterator is not powerful than RandomAccessIterator ? right?

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And then the link here

Did you at least *look* at your question's preview? "enter image description here"... — Angew is no longer proud of SO, Oct 19 '16 at 10:13
so sorry. I was not carefully press the Enter key and post it immediately. I will take care it next. — Andy Cong, Oct 19 '16 at 10:37

score 4 · Answer 1 · edited Jun 20 '20 at 09:12

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One non-contiguous container with random-access iterators is std::deque. Quoting the cppreference site:

As opposed to std::vector, the elements of a deque are not stored contiguously: typical implementations use a sequence of individually allocated fixed-size arrays.

The complexity (efficiency) of common operations on deques is as follows:

Random access - constant O(1)

Insertion or removal of elements at the end or beginning - constant O(1)

Insertion or removal of elements - linear O(n)

edited Jun 20 '20 at 09:12

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answered Oct 19 '16 at 10:14

Angew is no longer proud of SO

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oh,yeah. I saw it. thx. Aside from the std::deque. and any else ? – Andy Cong Oct 19 '16 at 10:33
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Also, `vector`. – T.C. Oct 19 '16 at 15:32
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@T.C. The iterator of `vector` doesn’t even satisfy [ForwardIterator](http://en.cppreference.com/w/cpp/concept/ForwardIterator), because `vector::iterator::reference` is not `bool&` or `const bool&`. – Daniel H Oct 09 '17 at 16:24

What kind of iterators supports random access but not contiguous storage in C++?

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