Converting accented characters from QString to std::string returns mangled text

Question

If my QString's value is

WeŠ.txt

the function QString::toStdString() will return

WeÅ .txt

whereas the function QString::toStdU16String will return the actual string

WeŠ.txt.

Why is that ? Š is a UTF-8 character as can be seen here : http://www.fileformat.info/info/charset/UTF-8/list.htm.