Is it legal to write to std::string?

Question

In std::string there are only const members to fetch the data like c_str(). However I can get a reference to the first element of the string via operator[] and

Answer 1

Herb Sutter has this to say (http://herbsutter.wordpress.com/2008/04/07/cringe-not-vectors-are-guaranteed-to-be-contiguous/#comment-483):

current ISO C++ does require &str[0] to cough up a pointer to contiguous string data (but not necessarily null-terminated!), so there wasn’t much leeway for implementers to have non-contiguous strings, anyway. For C++0x we have already adopted the guarantee that std::string contents must indeed be stored contiguously. For details, see http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#530

And Matt Austern says similar in the referenced document (http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#530).

So, it seems that you can assume that once you call str[0] you do get a modifyable array of characters (but note that it is not required to be null terminated).