c++ - Does std::string need to store its character in a contiguous piece of memory?

Question

I know that in C++98, neither std::basic_string<> nor std::vector<> were required to use contiguous storage. This was seen as an oversight for std::vector<> as soon as it was pointed out, and, if I remember correctly, got fixed with C++03.

I seem to remember having read about discussions requiring std::basic_string<> to use contiguous storage back when C++11 was still called C++0x, but I haven't followed the discussion closely back then, and am still restricted to C++03 at work, so I am not sure what became of it.

So is std::basic_string<> required to use contiguous storage? (If so, then which version of the standard required it first?)

^{In case you wonder: This is important if you have code passing the result of &str[0] to a function expecting a contiguous piece of memory to write to. (I know about str.data(), but for obvious reasons old code doesn't use it.)}

Answer 1

The C++11 standard, basic_string 21.4.1.5,

The char-like objects in a basic_string object shall be stored contiguously. That is, for any basic_string object s, the identity &*(s.begin() + n) == &*s.begin() + n shall hold for all values of n such that 0 <= n < s.size().