Question

Could somebody explain how the following example works?

I don’t understand how this can work without using boost::locale::to_upper instead of boost::to_upper?

Will boost::to_upper use locale::global? I thought the regular facet/locale stuff couldn’t support utf-8 since it works on character basis?

EDIT:

Also is gen(“UTF-8”) valid?

Furthermore, how does boost::locale work with boost::regex, is boost::32regex still needed to work with utf-8 strings?

Answer 1

There are two uses of to_upper() in this example:

1. to_upper("grüßen") which is resolved via the using declaration using namespace boost::locale. This is said to produce the correct result, i.e. GRÜSSEN.
2. boost::to_upper_copy(std::string("grüßen")) which seems to be the version you are referring to as “boost::to_upper”. This is said to produce the incorrect result, i.e. GRÜßEN.

It seems that the root cause of your misunderstanding was that you assumed that “boost::to_upper” does the right things while it is actually meant to do the wrong thing.