About the underlying storage of std::basic_string

Question

After reading through the description about std::basic_string on cppreference, I'm uncertain about the following two questions regarding the underlying storage of std::basic_string:

1) Since C++11, does the contiguity of std::basic_string extends to the terminating null character? Note that str[str.size()] returns a reference to a terminating null character. But I want to make sure whether this is the one after str[str.size() - 1].

2) Since C++11, data() and c_str() become equivalent. But does it hold that data() == c_str() == &front()?

Any quotation from the standard would be appreciated.

Answer 1

21.4.1.7 basic_string accessors

const charT* c_str() const noexcept;

const charT* data() const noexcept;

1 Returns: A pointer p such that p + i == &operator[](i) for each i in [0,size()].

2 Complexity: constant time.

This effectively requires that the terminating NUL be stored contiguously together with the character sequence (it forces an additional requirement on operator[] that s[s.size()] not do anything fancy, though the plain text of 21.4.5 appears to give it some latitude).

It also explicitly requires that s.c_str() == &s[0], which in turn means that s.c_str() == &s.front() (front() is defined as operator[](0)).