How is C++ std::vector implemented?

Question

I have been using std::vector a lot, and recently I asked myself this question: \"How is std::vector implemented?\"

I had two alternatives:

Answer 1

Section 23.2.4, ¶1 of the standard requires that arithmetic on pointers into a vector work the same as with pointers into an array.

The elements of a vector are stored contiguously, meaning that if v is a vector where T is some type other than bool, then it obeys the identity &v[n] == &v[0] + n for all 0 <= n < v.size().

This guarantees that the storage is in an array. Of course, if you resize the array to be bigger, it might get moved in memory.