Array is implemented with copy-on-write behaviour – you’ll get it regardless of any compiler optimisations (although of course, optimisations can decrease the number of cases where a copy needs to happen). At a basic level, Array is just a structure that holds a reference to a heap-allocated buffer containing the elements – therefore multiple Array … Read more
It’s not allowed, because as per the standard 21.4.1 p6, invalidation of iterators/references is only allowed for — as an argument to any standard library function taking a reference to non-const basic_string as an argument. — Calling non-const member functions, except operator[], at, front, back, begin, rbegin, end, and rend. For a COW string, calling … Read more
I was going to write up my own explanation but this Wikipedia article pretty much sums it up. Here is the basic concept: Copy-on-write (sometimes referred to as “COW”) is an optimization strategy used in computer programming. The fundamental idea is that if multiple callers ask for resources which are initially indistinguishable, you can give … Read more