<iterator>
advance
· back_insert_iterator
· back_inserter
· bidirectional_iterator_tag
· distance
· forward_iterator_tag
· front_insert_iterator
· front_inserter
· input_iterator_tag
· insert_iterator
· inserter
· istream_iterator
· istreambuf_iterator
· iterator
· iterator_traits
· operator!=
· operator==
· operator<
· operator<=
· operator>
· operator>=
· operator+
· operator-
· ostream_iterator
· ostreambuf_iterator
· output_iterator_tag
· random_access_iterator_tag
· reverse_iterator
Include the STL
standard header <iterator>
to define a number of classes, template classes, and template
functions that aid in the declaration and manipulation of iterators.
namespace std { struct input_iterator_tag; struct output_iterator_tag; struct forward_iterator_tag; struct bidirectional_iterator_tag; struct random_access_iterator_tag; // TEMPLATE CLASSES template<class Category, class Ty, class Diff, class Pointer, class Reference> struct iterator; template<class Iter> struct iterator_traits; template<class Ty> struct iterator_traits<Ty *>; template<class Ty> struct iterator_traits<const Ty *>; template<class RanIt> class reverse_iterator; template<class Container> class back_insert_iterator; template<class Container> class front_insert_iterator; template<class Container> class insert_iterator; template<class Ty, class Elem, class Tr, class Diff> class istream_iterator; template<class Ty, class Elem, class Tr> class ostream_iterator; template<class Elem, class Tr> class istreambuf_iterator; template<class Elem, class Tr> class ostreambuf_iterator; // TEMPLATE FUNCTIONS template<class RanIt> bool operator==( const reverse_iterator<RanIt>& left, const reverse_iterator<RanIt>& right); template<class Ty, class Elem, class Tr, class Diff> bool operator==( const istream_iterator<Ty, Elem, Tr, Diff>& left, const istream_iterator<Ty, Elem, Tr, Diff>& right); template<class Elem, class Tr> bool operator==( const istreambuf_iterator<Elem, Tr>& left, const istreambuf_iterator<Elem, Tr>& right); template<class RanIt> bool operator!=( const reverse_iterator<RanIt>& left, const reverse_iterator<RanIt>& right); template<class Ty, class Elem, class Tr, class Diff> bool operator!=( const istream_iterator<Ty, Elem, Tr, Diff>& left, const istream_iterator<Ty, Elem, Tr, Diff>& right); template<class Elem, class Tr> bool operator!=( const istreambuf_iterator<Elem, Tr>& left, const istreambuf_iterator<Elem, Tr>& right); template<class RanIt> bool operator<( const reverse_iterator<RanIt>& left, const reverse_iterator<RanIt>& right); template<class RanIt> bool operator>( const reverse_iterator<RanIt>& left, const reverse_iterator<RanIt>& right); template<class RanIt> bool operator<=( const reverse_iterator<RanIt>& left, const reverse_iterator<RanIt>& right); template<class RanIt> bool operator>=( const reverse_iterator<RanIt>& left, const reverse_iterator<RanIt>& right); template<class RanIt> Diff operator-( const reverse_iterator<RanIt>& left, const reverse_iterator<RanIt>& right); template<class RanIt> reverse_iterator<RanIt> operator+( Diff off, const reverse_iterator<RanIt>& right); template<class Container> back_insert_iterator<Container> back_inserter(Container& cont); template<class Container> front_insert_iterator<Container> front_inserter(Container& cont); template<class Container, class Iter> insert_iterator<Container> inserter(Container& cont, Iter it); template<class InIt, class Diff> void advance(InIt& it, Diff off); template<class Init> iterator_traits<InIt>::difference_type distance(InIt first, InIt last); };
advance
template<class InIt, class Diff> void advance(InIt& it, Diff off);
The template function effectively advances it
by
incrementing it off
times. If InIt
is
a random-access iterator type, the function evaluates the expression
it += off
. Otherwise, it performs each increment
by evaluating ++it
. If InIt
is an
input or forward iterator type, off
must not be negative.
back_insert_iterator
template<class Container> class back_insert_iterator : public iterator<output_iterator_tag, void, void, void, void> { public: typedef Container container_type; typedef typename Container::reference reference; explicit back_insert_iterator(Container& cont); back_insert_iterator& operator=(typename Container::const_reference val); back_insert_iterator& operator*(); back_insert_iterator& operator++(); back_insert_iterator operator++(int); protected: Container *container; };
The template class describes an output iterator object.
It inserts elements
into a container of type Container
, which it accesses via
the protected pointer object it stores called
container
.
The container must define:
const_reference
, which is the type of
a constant reference to an element of the sequence controlled by the containerreference
, which is the type of
a reference to an element of the sequence controlled by the containervalue_type
, which is the type of
an element of the sequence controlled by the containerpush_back(value_type val)
,
which appends a new element with value val
to the end of
the sequenceback_insert_iterator::back_insert_iterator
explicit back_insert_iterator(Container& cont);
The constructor initializes
container
with &cont
.
back_insert_iterator::container_type
typedef Container container_type;
The type is a synonym for the template parameter Container
.
back_insert_iterator::operator*
back_insert_iterator& operator*();
The member function returns *this
.
back_insert_iterator::operator++
back_insert_iterator& operator++(); back_insert_iterator operator++(int);
The member functions both return *this
.
back_insert_iterator::operator=
back_insert_iterator& operator=(typename Container::const_reference val);
The member function evaluates
container->
push_back(val)
, then returns *this
->
back_insert_iterator::reference
typedef typename Container::reference reference;
The type describes a reference to an element of the sequence controlled by the associated container.
back_inserter
template<class Container> back_insert_iterator<Container> back_inserter(Container& cont);
The template function returns
back_insert_iterator<Container>(cont)
.
bidirectional_iterator_tag
struct bidirectional_iterator_tag : public forward_iterator_tag { };
The type is the same as
iterator<Iter>::iterator_category
when Iter
describes an object that can serve as a
bidirectional iterator.
distance
template<class Init> typename iterator_traits<InIt>::difference_type distance(InIt first, InIt last);
The template function sets a count N
to zero. It then
effectively advances first
and increments N
until first == last
.
If InIt
is
a random-access iterator type, the function evaluates the expression
N += last - first
. Otherwise, it performs each iterator
increment by evaluating ++first
.
The function returns N
.
forward_iterator_tag
struct forward_iterator_tag : public input_iterator_tag { };
The type is the same as
iterator<Iter>::iterator_category
when Iter
describes an object that can serve as a
forward iterator.
front_insert_iterator
template<class Container> class front_insert_iterator : public iterator<output_iterator_tag, void, void, void, void> { public: typedef Container container_type; typedef typename Container::reference reference; explicit front_insert_iterator(Container& cont); front_insert_iterator& operator=(typename Container::const_reference val); front_insert_iterator& operator*(); front_insert_iterator& operator++(); front_insert_iterator operator++(int); protected: Container *container; };
The template class describes an output iterator object.
It inserts elements
into a container of type Container
, which it accesses via
the protected pointer object it stores called
container
.
The container must define:
const_reference
, which is the type of
a constant reference to an element of the sequence controlled by the containerreference
, which is the type of
a reference to an element of the sequence controlled by the containervalue_type
, which is the type of
an element of the sequence controlled by the containerpush_front(value_type val)
,
which prepends a new element with value val
to the beginning of
the sequencefront_insert_iterator::container_type
typedef Container container_type;
The type is a synonym for the template parameter Container
.
front_insert_iterator::front_insert_iterator
explicit front_insert_iterator(Container& cont);
The constructor initializes
container
with &cont
.
front_insert_iterator::operator*
front_insert_iterator& operator*();
The member function returns *this
.
front_insert_iterator::operator++
front_insert_iterator& operator++(); front_insert_iterator operator++(int);
The member functions both return *this
.
front_insert_iterator::operator=
front_insert_iterator& operator=(typename Container::const_reference val);
The member function evaluates
container->
push_front(val)
, then returns *this
.
front_insert_iterator::reference
typedef typename Container::reference reference;
The type describes a reference to an element of the sequence controlled by the associated container.
front_inserter
template<class Container> front_insert_iterator<Container> front_inserter(Container& cont);
The template function returns
front_insert_iterator<Container>(cont)
.
input_iterator_tag
struct input_iterator_tag { };
The type is the same as
iterator<Iter>::iterator_category
when Iter
describes an object that can serve as an
input iterator.
insert_iterator
template<class Container> class insert_iterator : public iterator<output_iterator_tag, void, void, void, void> { public: typedef Container container_type; typedef typename Container::reference reference; insert_iterator(Container& cont, typename Container::iterator it); insert_iterator& operator=(typename Container::const_reference val); insert_iterator& operator*(); insert_iterator& operator++(); insert_iterator& operator++(int); protected: Container *container; typename Container::iterator iter; };
The template class describes an output iterator object.
It inserts elements
into a container of type Container
, which it accesses via
the protected pointer object it stores called
container
.
It also stores the protected iterator object, of class
Container::iterator
, called
iter
.
The container must define:
const_reference
, which is the type of
a constant reference to an element of the sequence controlled by the containeriterator
, which is the type of
an iterator for the containerreference
, which is the type of
a reference to an element of the sequence controlled by the containervalue_type
, which is the type of
an element of the sequence controlled by the containerinsert(iterator it,
value_type val)
,
which inserts a new element with value val
immediately before
the element designated by it
in the controlled sequence,
then returns an iterator that designates the inserted elementinsert_iterator::container_type
typedef Container container_type;
The type is a synonym for the template parameter Container
.
insert_iterator::insert_iterator
insert_iterator(Container& cont, typename Container::iterator it);
The constructor initializes
container
with &cont
, and
iter
with it
.
insert_iterator::operator*
insert_iterator& operator*();
The member function returns *this
.
insert_iterator::operator++
insert_iterator& operator++(); insert_iterator& operator++(int);
The member functions both return *this
.
insert_iterator::operator=
insert_iterator& operator=(typename Container::const_reference val);
The member function evaluates
iter =
container->
insert(iter, val)
, then returns *this
.
insert_iterator::reference
typedef typename Container::reference reference;
The type describes a reference to an element of the sequence controlled by the associated container.
inserter
template<class Container, class Iter> insert_iterator<Container> inserter(Container& cont, Iter it);
The template function returns
insert_iterator<Container>(cont, it)
.
istream_iterator
template<class Ty, class Elem = char, class Tr = char_traits> class Diff = ptrdiff_t> class istream_iterator : public iterator<input_iterator_tag, Ty, Diff, const Ty *, const Ty&> { public: typedef Elem char_type; typedef Tr traits_type; typedef basic_istream<Elem, Tr> istream_type; istream_iterator(); istream_iterator(istream_type& istr); const Ty& operator*() const; const Ty *operator->() const; istream_iterator<Ty, Elem, Tr, Diff>& operator++(); istream_iterator<Ty, Elem, Tr, Diff> operator++(int); };
The template class describes an input iterator object.
It extracts objects of class Ty
from an input stream, which it accesses via an object it stores,
of type pointer to
basic_istream<Elem, Tr>
.
After constructing or incrementing an object of class
istream_iterator
with a non-null stored pointer,
the object attempts to extract and store an object of type
Ty
from the associated input stream. If the extraction
fails, the object effectively replaces the stored pointer with
a null pointer (thus making an end-of-sequence indicator).
istream_iterator::char_type
typedef Elem char_type;
The type is a synonym for the template parameter Elem
.
istream_iterator::istream_iterator
istream_iterator(); istream_iterator(istream_type& istr);
The first constructor initializes the input stream pointer
with a null pointer.
The second constructor initializes the input stream pointer
with &istr
, then attempts to extract and store
an object of type Ty
.
istream_iterator::istream_type
typedef basic_istream<Elem, Tr> istream_type;
The type is a synonym for
basic_istream<Elem, Tr>
.
istream_iterator::operator*
const Ty& operator*() const;
The operator returns the stored object of type Ty
.
istream_iterator::operator->
const Ty *operator->() const;
The operator returns &**this
.
istream_iterator::operator++
istream_iterator<Ty, Elem, Tr, Diff>& operator++(); istream_iterator<Ty, Elem, Tr, Diff> operator++(int);
The first operator attempts to extract and store an object
of type Ty
from the associated input stream. The second
operator makes a copy of the object, increments the object, then
returns the copy.
istream_iterator::traits_type
typedef Tr traits_type;
The type is a synonym for the template parameter Tr
.
istreambuf_iterator
template<class Elem, class Tr = char_traits<Elem> > class istreambuf_iterator : public iterator<input_iterator_tag, Elem, typename Ty::off_type, Elem *, Elem&> { public: typedef Elem char_type; typedef Tr traits_type; typedef typename Tr::int_type int_type; typedef basic_streambuf<Elem, Tr> streambuf_type; typedef basic_istream<Elem, Tr> istream_type; istreambuf_iterator(streambuf_type *strbuf = 0) throw(); istreambuf_iterator(istream_type& istr) throw(); Elem operator*() const; istreambuf_iterator& operator++(); istreambuf_iterator operator++(int); bool equal(const istreambuf_iterator& right) const; };
The template class describes an input iterator object.
It extracts elements of class Elem
from an input stream buffer,
which it accesses via an object it stores,
of type pointer to
basic_streambuf<Elem,
Tr>
.
After constructing or incrementing an object of class
istreambuf_iterator
with a non-null stored pointer,
the object effectively attempts to extract and store an object of type
Elem
from the associated input stream.
(The extraction may be delayed, however, until the object
is actually dereferenced or copied.) If the extraction
fails, the object effectively replaces the stored pointer with
a null pointer (thus making an end-of-sequence indicator).
istreambuf_iterator::char_type
typedef Elem char_type;
The type is a synonym for the template parameter Elem
.
istreambuf_iterator::equal
bool equal(const istreambuf_iterator& right) const;
The member function returns true only if the stored stream buffer
pointers for the object and right
are both null pointers
or are both non-null pointers.
istreambuf_iterator::int_type
typedef typename Tr::int_type int_type;
The type is a synonym for
Ty::int_type
.
istreambuf_iterator::istream_type
typedef basic_istream<Elem, Tr> istream_type;
The type is a synonym for
basic_istream<Elem,
Tr>
.
istreambuf_iterator::istreambuf_iterator
istreambuf_iterator(streambuf_type *strbuf = 0) throw(); istreambuf_iterator(istream_type& istr) throw();
The first constructor initializes the input stream-buffer pointer
with strbuf
.
The second constructor initializes the input stream-buffer pointer with
istr.rdbuf()
,
then (eventually) attempts to extract and store
an object of type Elem
.
istreambuf_iterator::operator*
Elem operator*() const;
The operator returns the stored object of type Elem
.
istreambuf_iterator::operator++
istreambuf_iterator& operator++(); istreambuf_iterator operator++(int);
The first operator (eventually) attempts to extract and store an object
of type Elem
from the associated input stream. The second
operator makes a copy of the object, increments the object, then
returns the copy.
istreambuf_iterator::streambuf_type
typedef basic_streambuf<Elem, Tr> streambuf_type;
The type is a synonym for
basic_streambuf<Elem,
Tr>
.
istreambuf_iterator::traits_type
typedef Tr traits_type;
The type is a synonym for the template parameter Tr
.
iterator
template<class Category, class Ty, class Diff = ptrdiff_t class Pointer = Ty *, class Reference = Ty&> struct iterator { typedef Category iterator_category; typedef Ty value_type; typedef Diff difference_type; typedef Pointer pointer; typedef Reference reference; };
The template class can serve as a convenient base class
for an iterator class that you define.
It defines the member types
iterator_category
(a synonym for the template parameter Category
),
value_type
(a synonym for the template parameter Ty
),
difference_type
(a synonym for the template parameter Diff
),
pointer
(a synonym for the template parameter Pointer
), and
reference
(a synonym for the template parameter Reference
).
Note that value_type
should not be a constant
type even if pointer
points at an object of const type
and reference
designates an object of const type.
iterator_traits
template<class Iter> struct iterator_traits { typedef typename Iter::iterator_category iterator_category; typedef typename Iter::value_type value_type; typedef typename Iter::difference_type difference_type; typedef typename Iter::pointer pointer; typedef typename Iter::reference reference; }; template<class Ty> struct iterator_traits<Ty *> { typedef random_access_iterator_tag iterator_category; typedef Ty value_type; typedef ptrdiff_t difference_type; typedef Ty *pointer; typedef Ty& reference; }; template<class Ty> struct iterator_traits<const Ty *> { typedef random_access_iterator_tag iterator_category; typedef Ty value_type; typedef ptrdiff_t difference_type; typedef const Ty *pointer; typedef const Tr& reference; };
The template class determines several critical types associated
with the iterator type Iter
.
It defines the member types
iterator_category
(a synonym for Iter::iterator_category
),
value_type
(a synonym for Iter::value_type
),
difference_type
(a synonym for Iter::difference_type
),
pointer
(a synonym for Iter::pointer
), and
reference
(a synonym for Iter::reference
).
The partial specializations determine the critical types associated
with an object pointer type Ty *
or const Ty *
. In this
implementation,
you can also use several template functions that do not make use of
partial specialization:
template<class Category, class Ty, class Diff> C _Iter_cat(const iterator<Category, Ty, Diff>&); template<class Ty> random_access_iterator_tag _Iter_cat(const Ty *); template<class Category, class Ty, class Diff> Ty *_Val_type(const iterator<Category, Ty, Diff>&); template<class Ty> Ty *_Val_type(const Ty *); template<class Category, class Ty, class Diff> Diff *_Dist_type(const iterator<Category, Ty, Diff>&); template<class Ty> ptrdiff_t *_Dist_type(const Ty *);
which determine several of the same types a bit more indirectly. You use these functions as arguments on a function call. Their sole purpose is to supply a useful template class parameter to the called function.
operator!=
template<class RanIt> bool operator!=( const reverse_iterator<RanIt>& left, const reverse_iterator<RanIt>& right); template<class Ty, class Elem, class Tr, class Diff> bool operator!=( const istream_iterator<Ty, Elem, Tr, Diff>& left, const istream_iterator<Ty, Elem, Tr, Diff>& right); template<class Elem, class Tr> bool operator!=( const istreambuf_iterator<Elem, Tr>& left, const istreambuf_iterator<Elem, Tr>& right);
The template operator returns !(left == right)
.
operator==
template<class RanIt> bool operator==( const reverse_iterator<RanIt>& left, const reverse_iterator<RanIt>& right); template<class Ty, class Elem, class Tr, class Diff> bool operator==( const istream_iterator<Ty, Elem, Tr, Diff>& left, const istream_iterator<Ty, Elem, Tr, Diff>& right); template<class Elem, class Tr> bool operator==( const istreambuf_iterator<Elem, Tr>& left, const istreambuf_iterator<Elem, Tr>& right);
The first template operator returns true only if
left.current ==
right.current
. The second template operator returns true only
if both left
and right
store the same
stream pointer. The third template operator returns
left.equal(right)
.
operator<
template<class RanIt> bool operator<( const reverse_iterator<RanIt>& left, const reverse_iterator<RanIt>& right);
The template operator returns
right.current <
left.current
[sic].
operator<=
template<class RanIt> bool operator<=( const reverse_iterator<RanIt>& left, const reverse_iterator<RanIt>& right);
The template operator returns !(right < left)
.
operator>
template<class RanIt> bool operator>( const reverse_iterator<RanIt>& left, const reverse_iterator<RanIt>& right);
The template operator returns right < left
.
operator>=
template<class RanIt> bool operator>=( const reverse_iterator<RanIt>& left, const reverse_iterator<RanIt>& right);
The template operator returns !(left < right)
.
operator+
template<class RanIt> reverse_iterator<RanIt> operator+(Diff off, const reverse_iterator<RanIt>& right);
The template operator returns right + off
.
operator-
template<class RanIt> Diff operator-( const reverse_iterator<RanIt>& left, const reverse_iterator<RanIt>& right);
The template operator returns
right.current -
left.current
[sic].
ostream_iterator
template<class Ty, class Elem = char, class Tr = char_traits<Elem> > class ostream_iterator : public iterator<output_iterator_tag, void, void, void, void> { public: typedef Elem char_type; typedef Tr traits_type; typedef basic_ostream<Elem, Tr> ostream_type; ostream_iterator(ostream_type& ostr); ostream_iterator(ostream_type& ostr, const Elem *delim); ostream_iterator<Ty, Elem, Tr>& operator=(const Ty& val); ostream_iterator<Ty, Elem, Tr>& operator*(); ostream_iterator<Ty, Elem, Tr>& operator++(); ostream_iterator<Ty, Elem, Tr> operator++(int); };
The template class describes an output iterator object.
It inserts objects of class Ty
into an output stream, which it accesses via an object it stores,
of type pointer to
basic_ostream<Elem, Tr>
.
It also stores a pointer to a delimiter string, a
null-terminated string
of elements of type Elem
, which is appended after
each insertion. (Note that the string itself is not copied
by the constructor.
ostream_iterator::char_type
typedef Elem char_type;
The type is a synonym for the template parameter Elem
.
ostream_iterator::operator*
ostream_iterator<Ty, Elem, Tr>& operator*();
The operator returns *this
.
ostream_iterator::operator++
ostream_iterator<Ty, Elem, Tr>& operator++(); ostream_iterator<Ty, Elem, Tr> operator++(int);
The operators both return *this
.
ostream_iterator::operator=
ostream_iterator<Ty, Elem, Tr>& operator=(const Ty& val);
The operator inserts val
into the
output stream associated with the object,
then returns *this
.
ostream_iterator::ostream_iterator
ostream_iterator(ostream_type& ostr); ostream_iterator(ostream_type& ostr, const Elem *delim);
The first constructor initializes the output stream pointer
with &ostr
. The delimiter string pointer designates an
empty string. The second constructor initializes the output stream
pointer with &ostr
and the delimiter string pointer
with delim
.
ostream_iterator::ostream_type
typedef basic_ostream<Elem, Tr> ostream_type;
The type is a synonym for
basic_ostream<Elem, Tr>
.
ostream_iterator::traits_type
typedef Tr traits_type;
The type is a synonym for the template parameter Tr
.
ostreambuf_iterator
template<class Elem, class Tr = char_traits<Elem> > class ostreambuf_iterator : public iterator<output_iterator_tag, void, void, void, void> { public: typedef Elem char_type; typedef Tr traits_type; typedef basic_streambuf<Elem, Tr> streambuf_type; typedef basic_ostream<Elem, Tr> ostream_type; ostreambuf_iterator(streambuf_type *stebuf) throw(); ostreambuf_iterator(ostream_type& ostr) throw(); ostreambuf_iterator& operator=(Elem ch); ostreambuf_iterator& operator*(); ostreambuf_iterator& operator++(); T1 operator++(int); bool failed() const throw(); };
The template class describes an output iterator object.
It inserts elements of class Elem
into an output stream buffer,
which it accesses via an object it stores,
of type pointer to
basic_streambuf<Elem, Tr>
.
ostreambuf_iterator::char_type
typedef Elem char_type;
The type is a synonym for the template parameter Elem
.
ostreambuf_iterator::failed
bool failed() const throw();
The member function returns true only if an insertion into the output stream buffer has earlier failed.
ostreambuf_iterator::operator*
ostreambuf_iterator& operator*();
The operator returns *this
.
ostreambuf_iterator::operator++
ostreambuf_iterator& operator++(); T1 operator++(int);
The first operator returns *this
. The second operator
returns an object of some type T1
that can be converted to
ostreambuf_iterator<Elem, Tr>
.
ostreambuf_iterator::operator=
ostreambuf_iterator& operator=(Elem ch);
The operator inserts ch
into the associated stream buffer,
then returns *this
.
ostreambuf_iterator::ostream_type
typedef basic_ostream<Elem, Tr> ostream_type;
The type is a synonym for
basic_ostream<Elem,
Tr>
.
ostreambuf_iterator::ostreambuf_iterator
ostreambuf_iterator(streambuf_type *strbuf) throw(); ostreambuf_iterator(ostream_type& ostr) throw();
The first constructor initializes the output stream-buffer pointer
with strbuf
.
The second constructor initializes the output stream-buffer pointer with
ostr.rdbuf()
.
(The stored pointer must not be a null pointer.)
ostreambuf_iterator::streambuf_type
typedef basic_streambuf<Elem, Tr> streambuf_type;
The type is a synonym for basic_streambuf<Elem, Tr>
.
ostreambuf_iterator::traits_type
typedef Tr traits_type;
The type is a synonym for the template parameter Tr
.
output_iterator_tag
struct output_iterator_tag { };
The type is the same as
iterator<Iter>::iterator_category
when Iter
describes an object that can serve as a
output iterator.
random_access_iterator_tag
struct random_access_iterator_tag : public bidirectional_iterator_tag { };
The type is the same as
iterator<Iter>::iterator_category
when Iter
describes an object that can serve as a
random-access iterator.
reverse_iterator
template<class RanIt> class reverse_iterator : public iterator< typename iterator_traits<RanIt>::iterator_category, typename iterator_traits<RanIt>::value_type, typename iterator_traits<RanIt>::difference_type, typename iterator_traits<RanIt>::pointer, typename iterator_traits<RanIt>::reference> { typedef typename iterator_traits<RanIt>::difference_type difference_type; typedef typename iterator_traits<RanIt>::pointer pointer; typedef typename iterator_traits<RanIt>::reference reference; public: typedef RanIt iterator_type; reverse_iterator(); explicit reverse_iterator(RanIt right); template<class Ty> reverse_iterator(const reverse_iterator<Ty>& right); RanIt base() const; reference operator*() const; pointer operator->() const; reverse_iterator& operator++(); reverse_iterator operator++(int); reverse_iterator& operator--(); reverse_iterator operator--(); reverse_iterator& operator+=(difference_type off); reverse_iterator operator+(difference_type off) const; reverse_iterator& operator-=(difference_type off); reverse_iterator operator-(difference_type off) const; reference operator[](difference_type off) const; protected: RanIt current; };
The template class describes an object that behaves like a
random-access iterator, only in reverse. 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 reference
. Typically, reference
is
type Tr&
.
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.
Several STL containers specialize
reverse_iterator
for RanIt
a bidirectional iterator.
In these cases, you must not call any of the member functions operator+=
,
operator+
, operator-=
, operator-
, or
operator[]
.
reverse_iterator::base
RanIt base() const;
The member function returns
current
.
reverse_iterator::difference_type
typedef typename iterator_traits<RanIt>::difference_type difference_type;
The type is a synonym for the iterator trait
typename iterator_traits<RanIt>::pointer
.
reverse_iterator::iterator_type
typedef RanIt iterator_type;
The type is a synonym for the template parameter RanIt
.
reverse_iterator::operator*
reference operator*() const;
The operator returns
*(current - 1)
.
reverse_iterator::operator+
reverse_iterator operator+(difference_type off) const;
The operator returns reverse_iterator(*this) += off
.
reverse_iterator::operator++
reverse_iterator& operator++(); reverse_iterator operator++(int);
The first (preincrement) operator evaluates
--current
.
then returns *this
.
The second (postincrement) operator makes a copy of *this
,
evaluates --current
, then returns the copy.
reverse_iterator::operator+=
reverse_iterator& operator+=(difference_type off);
The operator evaluates
current - off
.
then returns *this
.
reverse_iterator::operator-
reverse_iterator operator-(difference_type off) const;
The operator returns reverse_iterator(*this) -= off
.
reverse_iterator::operator--
reverse_iterator& operator--(); reverse_iterator operator--();
The first (predecrement) operator evaluates
++current
.
then returns *this
.
The second (postdecrement) operator makes a copy of *this
,
evaluates ++current
, then returns the copy.
reverse_iterator::operator-=
reverse_iterator& operator-=(difference_type off);
The operator evaluates
current + off
.
then returns *this
.
reverse_iterator::operator->
pointer operator->() const;
The operator returns &**this
.
reverse_iterator::operator[]
reference operator[](difference_type off) const;
The operator returns *(*this + off)
.
reverse_iterator::pointer
typedef typename iterator_traits<RanIt>::pointer pointer;
The type is a synonym for the iterator trait
typename iterator_traits<RanIt>::pointer
.
reverse_iterator::reference
typedef typename iterator_traits<RanIt>::reference reference;
The type is a synonym for the iterator trait
typename iterator_traits<RanIt>::reference
.
reverse_iterator::reverse_iterator
reverse_iterator(); explicit reverse_iterator(RanIt right); template<class Ty> reverse_iterator(const reverse_iterator<Ty>& right);
The first constructor initializes
current
with its default constructor. The second constructor initializes
current
with
right.current
.
The template constructor initializes current
with right.base()
.
See also the Table of Contents and the Index.
Copyright © 1994-2002 by P.J. Plauger. Portions derived from work copyright © 1994 by Hewlett-Packard Company. All rights reserved.