How does Microsoft handle the fact that UTF-16 is a variable length encoding in their C++ standard library implementation

Question

Having a variable length encoding is indirectly forbidden in the standard.

So I have several questions:

How is the following part of the standard handled?

Answer 1

STL deals with strings as simply a wrapper for an array of characters therefore size() or length() on an STL string will tell you how many char or wchar_t elements it contains and not necessarily the number of printable characters it would be in a string.