template<class RanIt,
class T = iterator_traits<RanIt>::value_type,
class Ref = T&,
class Ptr = T *, class Dist = ptrdiff_t>
class reverse_iterator
: public iterator<random_access_iterator_tag, T, Dist> {
public:
typedef RanIt iter_type;
typedef Ref reference_type;
typedef Ptr pointer_type;
reverse_iterator();
explicit reverse_iterator(RanIt x);
RanIt base() const;
Ref operator*() const;
Ptr operator->() const;
reverse_iterator& operator++();
reverse_iterator operator++(int);
reverse_iterator& operator--();
reverse_iterator operator--();
reverse_iterator& operator+=(Dist n);
reverse_iterator operator+(Dist n) const;
reverse_iterator& operator-=(Dist n);
reverse_iterator operator-(Dist n) const;
Ref operator[](Dist n) const;
protected:
RanIt current;
};
The template class describes an object that behaves like a random-access iterator of class
iterator
<random_access_iterator_tag,
T
,
Dist
>
. It stores a random-access iterator of type RanIt
in the
protected object current
. Incrementing the object x
of type reverse_iterator
decrements x.current
, and
decrementing x
increments x.current
. Moreover, the expression *x
evaluates to *(current - 1)
, of type Ref
.
Typically, Ref
is type T&
.
Thus, you can use an object of class reverse_iterator
to access in reverse order a sequence that is traversed in
order by a random-access iterator.