C++ concepts: BidirectionalIterator
From cppreference.com
A BidirectionalIterator is a ForwardIterator that can be moved in both directions (i.e. incremented and decremented).
[edit] Requirements
-
ForwardIterator -
operator--with equivalent conditions asoperator++
A mutable BidirectionalIterator is a BidirectionalIterator that additionally satisfies the OutputIterator requirements.