[Boost-users] Re: Key iterators

Chris Goller writes:

I'm just getting into boost and I really like it.

I would like to iterate over keys of a multimap.

so it would look like this:

std::multimap::key_iterator i = map.beginkey(); i != map.endkey(); i++ at each i++ it would move to the next key.

-or-

for_each(map.beginkey(), map.endkey(), whatever);

Is this possible with the boost iterators?

You can't use that syntax, because there's no way to inject a key_iterator member into std::multimap. You could use a transform_iterator over the multimap's native iterator with select1st, defined as: struct select1st { template T& operator()(std::pair& p) const { return p.first } template T const& operator()(std::pair const& p) const { return p.first } }; HTH, -- Dave Abrahams Boost Consulting http://www.boost-consulting.com