Bug#642955: general: strptime pars not week number
I had a similar problem, and this bug report was the only similar
discussion I could find.
> So since you do not provide a precise day, strptime does not store a
> day. %W is thus probably quite useless indeed, but I don't think it is
> fixable with the design of glibc.
With that hint, I could actually get %W to do what I needed, by using
a format like %Y-%W-%u, and passing “1” for the %u. So for the
original question, parse "2001 38 1" with format "%Y %W %u", and
you'll get the first day (Monday) of week 38 in your struct tm.