Anthony Williams <anthony_w.geo@yahoo.com> writes:
David Abrahams <dave@boost-consulting.com> writes:
Anthony Williams <anthony_w.geo@yahoo.com> writes:
Gunter Winkler <guwi17@gmx.de> writes:
I tried to use boost::zip_iterator to sort 2 parallel arrays. Unfortunatly gcc does not compile the appended example because it can not convert
boost::detail::iterator_category_with_traversal<std::input_iterator_tag, boost::random_access_traversal_tag>
to either std::bidirectional_iterator_tag or std::random_access_iterator_tag. Thus it cannot dispatch the correct stl::__copy_backward() procedure.
Is sort() not yet supported?
As Dave already posted, zip_iterator doesn't support return forward or bidirectional iterators, so std::sort() cannot be used.
What you need is something like my tuple iterator (tupleit.zip from the files area on the boost yahoo group), which *does* support use with std::sort --- the iterator category of the tuple iterator is the minimum category of the supplied iterators.
How can sorting work? What type is returned from its operator* ?
For Forward, Bidi and Random-access Iterators, it returns a reference to a value held in the iterator.
I'm afraid those aren't conforming forward iterators :( 24.1.3: "If a and b are both dereferenceable, then a == b if and only if *a and *b are the same object. " Which is why we have to change counting_iterator to not be a forward iterator. -- Dave Abrahams Boost Consulting http://www.boost-consulting.com