Legal to overwrite std::string's null terminator?

Question

In C++11, we know that std::string is guaranteed to be both contiguous and null-terminated (or more pedantically, terminated by charT(), which in t

Answer 1

According to the spec, overwriting the terminating NUL should be undefined behavior. So, the right thing to do would be to allocate length+1 characters in the string, pass the string buffer to the C API, and then resize() back to length:

// "+ 1" to make room for the terminating NUL for the C API
std::string str(length + 1);

// Call the C API passing &str[0] to safely write to the string buffer
...

// Resize back to length
str.resize(length);

(FWIW, I tried the "overwriting NUL" approach on MSVC10, and it works fine.)