At Sun, 17 Apr 2011 08:43:00 +0900, Andrej van der Zee wrote:
Hi Dave,
Thanks for your email.
Not unless yours is a random access iterator. Is it?
Its a forward iterator. Changing it to a random access iterator solves it indeed.
This is my first iterator that I am writing, but why is it not possible to implement a custom distance method for forward iterators?
The implementation of std::distance only has the iterator category to go on when deciding whether to move by many steps or by one jump. There isn't any other information it can use.
Am I doing something conceptually wrong?
Could be. If you can move your iterator by N steps in one jump, maybe it should be a random access iterator.
Or should I specialize the std::distance() function?
You could specialize that function for specific iterator types. There's no partial specialization of function templates, and you're not allowed to add an overload to namespace std. -- Dave Abrahams BoostPro Computing http://www.boostpro.com