Invalidating iterators c Old men chat

An erase operation that erases the first element of a deque but not the last element invalidates only the erased elements.

An erase operation that erases neither the first element nor the last element of a deque invalidates the past-the-end iterator and all iterators and references to all the elements of the deque. Invalidates all references, pointers, and iterators referring to the elements of the container and may invalidate the past-the-end iterator.

invalidating iterators c-25

We have c 1 and n 1 rather than c and n because a dummy node is needed at the end of the sequence.

If we call f the capacity to size ratio c/n and assume that n is large enough, we have that m providing stability of references and iterators, in exchange for missing element contiguity and also some performance and memory overhead.

All the nodes are referenced from a contiguous array of pointers, but also every node contains an "up" pointer referring back to the associated array cell.

This up pointer is the key element to implementing stability and random accessibility: Iterators point to the nodes rather than to the pointer array.

Using g (...) it takes X seconds to perform a million lookups in a sorted vector Using a sorted vector instead of a set gives you faster lookup and much faster iteration, but at the cost of slower insertion.

Insertion into a set, using set::insert, is proportional to log N, but insertion into a sorted vector, (...) , is proportional to N.Whenever you insert something into a vector, vector::insert has to make room by shifting all of the elements that follow it.On average, if you're equally likely to insert a new element anywhere, you'll be shifting N/2 elements.We say then that s are unstable: by contrast, stable containers are those for which references and iterators to a given element remain valid as long as the element is not erased: examples of stable containers within the C standard library are (random access iterators, amortized constant time end insertion/deletion, minimal memory overhead, etc.)?The following image describes the layout of a possible data structure upon which to base the design of a stable vector: Each element is stored in its own separate node.Use only a valid pointer, reference, or iterator to refer to an element of a container.