23 Iterators library [iterators]

23.3 Iterator requirements [iterator.requirements]

23.3.5 C++17 iterator requirements [iterator.cpp17]

23.3.5.6 Bidirectional iterators [bidirectional.iterators]

Table 92: Cpp17BidirectionalIterator requirements (in addition to Cpp17ForwardIterator) [tab:bidirectionaliterator]
Expression
Return type
Operational
Assertion/note
semantics
pre-/post-condition
--r
X&
Preconditions: there exists s such that r == ++s.

Postconditions: r is dereferenceable.

--(++r) == r.

--r == --s implies r == s.

addressof(r) == addressof(--r).
r--
convertible to const X&
{ X tmp = r;
--r;
return tmp; }
*r--
reference