Discussion on answer by Vlad from Moscow: Почему длина строки не равна объявленной?

Imported from a comment discussion on http://ru.stackoverflow.com/questions/593512/%d0%9f%d0%be%d1%87%d0%b5%d0%bc%d1%83-%d0%b4%d0%bb%d0%b8%d0%bd%d0%b0-%d1%81%d1%82%d1%80%d0%be%d0%ba%d0%b8-%d0%bd%d0%b5-%d1%80%d0%b0%d0%b2%d0%bd%d0%b0-%d0%be%d0%b1%d1%8a%d1%8f%d0%b2%d0%bb%d0%b5%d0%bd%d0%bd%d0%be%d0%b9/593527#593527