Need current device i can use qstring and qvector to get this?

with this i get the path of my user:
QString homePath = QDir::homePath();

But i need to take the three first letters; I was thinking to change qstring to qvector and then take the three letters. And then return in string. Someone can share with me one example.

QString::left()
QDir::homePath() has nothing to do with "devices", especially not a "current device".