Does C 11's string::c_str() Eliminate Null Termination?

In C 11, string::c_str is no longer guaranteed to produce a null-terminated string.

Reason:

In C 11, string::c_str is defined as identical to string::data, which in turn is defined as equivalent to *(begin() n) for 0

Consequences:

This implies that string::c_str() may no longer return a null-terminated string, leading to potential errors in scenarios that assume such termination.

Solution:

The solution is to use string::c_str() only for compatibility with legacy code. For new code, use string::data() instead. While string::data() does not return a null-terminated string, it returns a pointer to the underlying buffer, which is guaranteed to be null-terminated internally.

Implementation Details:

Internally, strings are now required to use null-terminated buffers. The operator[] definition in section 21.4.5 requires that for size()

Additional Notes:

• &operator[](0) can be used as a synonym for c_str().
• The terminating null character must lie in the same buffer as the string data, as *(p size()) must be equal to charT(). Thus, even if the null character is initialized lazily, it is not possible to observe the buffer in an intermediate state.