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<HTML><HEAD><TITLE><iterator></TITLE></HEAD><BODY><H1><A NAME="<iterator>"><CODE><iterator></CODE></A></H1><HR><P><B><CODE><A HREF="#advance">advance</A>· <A HREF="#back_insert_iterator">back_insert_iterator</A>· <A HREF="#back_inserter">back_inserter</A>· <A HREF="#bidirectional_iterator_tag">bidirectional_iterator_tag</A>· <A HREF="#distance">distance</A>· <A HREF="#forward_iterator_tag">forward_iterator_tag</A>· <A HREF="#front_insert_iterator">front_insert_iterator</A>· <A HREF="#front_inserter">front_inserter</A>· <A HREF="#input_iterator_tag">input_iterator_tag</A>· <A HREF="#insert_iterator">insert_iterator</A>· <A HREF="#inserter">inserter</A>· <A HREF="#istream_iterator">istream_iterator</A>· <A HREF="#istreambuf_iterator">istreambuf_iterator</A>· <A HREF="#iterator">iterator</A>· <A HREF="#iterator_traits">iterator_traits</A>· <A HREF="#operator!=">operator!=</A>· <A HREF="#operator==">operator==</A>· <A HREF="#operator<">operator<</A>· <A HREF="#operator<=">operator<=</A>· <A HREF="#operator>">operator></A>· <A HREF="#operator>=">operator>=</A>· <A HREF="#operator+">operator+</A>· <A HREF="#operator-">operator-</A>· <A HREF="#ostream_iterator">ostream_iterator</A>· <A HREF="#ostreambuf_iterator">ostreambuf_iterator</A>· <A HREF="#output_iterator_tag">output_iterator_tag</A>· <A HREF="#random_access_iterator_tag">random_access_iterator_tag</A>· <A HREF="#reverse_iterator">reverse_iterator</A></CODE></B></P><HR><P>Include the <A HREF="index.html#STL">STL</A>standard header <B><CODE><iterator></CODE></B>to define a number of classes, template classes, and templatefunctions that aid in the declaration and manipulation of iterators.</P><PRE>namespace std {struct <B><A HREF="#input_iterator_tag">input_iterator_tag</A></B>;struct <B><A HREF="#output_iterator_tag">output_iterator_tag</A></B>;struct <B><A HREF="#forward_iterator_tag">forward_iterator_tag</A></B>;struct <B><A HREF="#bidirectional_iterator_tag">bidirectional_iterator_tag</A></B>;struct <B><A HREF="#random_access_iterator_tag">random_access_iterator_tag</A></B>; // TEMPLATE CLASSEStemplate<class Category, class Ty, class Diff, class Pointer, class Reference> struct <B><A HREF="#iterator">iterator</A></B>;template<class Iter> struct <B><A HREF="#iterator_traits">iterator_traits</A></B>;template<class Ty> struct <B><A HREF="#iterator_traits">iterator_traits</A></B><Ty *>;template<class Ty> struct <B>iterator_traits</B><const Ty *>;template<class RanIt> class <B><A HREF="#reverse_iterator">reverse_iterator</A></B>;template<class Container> class <B><A HREF="#back_insert_iterator">back_insert_iterator</A></B>;template<class Container> class <B><A HREF="#front_insert_iterator">front_insert_iterator</A></B>;template<class Container> class <B><A HREF="#insert_iterator">insert_iterator</A></B>;template<class Ty, class Elem, class Tr, class Diff> class <B><A HREF="#istream_iterator">istream_iterator</A></B>;template<class Ty, class Elem, class Tr> class <B><A HREF="#ostream_iterator">ostream_iterator</A></B>;template<class Elem, class Tr> class <B><A HREF="#istreambuf_iterator">istreambuf_iterator</A></B>;template<class Elem, class Tr> class <B><A HREF="#ostreambuf_iterator">ostreambuf_iterator</A></B>; // TEMPLATE FUNCTIONStemplate<class RanIt> bool <B><A HREF="#operator==">operator==</A></B>( const reverse_iterator<RanIt>& left, const reverse_iterator<RanIt>& right);template<class Ty, class Elem, class Tr, class Diff> bool <B><A HREF="#operator==">operator==</A></B>( const istream_iterator<Ty, Elem, Tr, Diff>& left, const istream_iterator<Ty, Elem, Tr, Diff>& right);template<class Elem, class Tr> bool <B><A HREF="#operator==">operator==</A></B>( const istreambuf_iterator<Elem, Tr>& left, const istreambuf_iterator<Elem, Tr>& right);template<class RanIt> bool <B><A HREF="#operator!=">operator!=</A></B>( const reverse_iterator<RanIt>& left, const reverse_iterator<RanIt>& right);template<class Ty, class Elem, class Tr, class Diff> bool <B><A HREF="#operator!=">operator!=</A></B>( const istream_iterator<Ty, Elem, Tr, Diff>& left, const istream_iterator<Ty, Elem, Tr, Diff>& right);template<class Elem, class Tr> bool <B><A HREF="#operator!=">operator!=</A></B>( const istreambuf_iterator<Elem, Tr>& left, const istreambuf_iterator<Elem, Tr>& right);template<class RanIt> bool <B><A HREF="#operator<">operator<</A></B>( const reverse_iterator<RanIt>& left, const reverse_iterator<RanIt>& right);template<class RanIt> bool <B><A HREF="#operator>">operator></A></B>( const reverse_iterator<RanIt>& left, const reverse_iterator<RanIt>& right);template<class RanIt> bool <B><A HREF="#operator<=">operator<=</A></B>( const reverse_iterator<RanIt>& left, const reverse_iterator<RanIt>& right);template<class RanIt> bool <B><A HREF="#operator>=">operator>=</A></B>( const reverse_iterator<RanIt>& left, const reverse_iterator<RanIt>& right);template<class RanIt> Diff <B><A HREF="#operator-">operator-</A></B>( const reverse_iterator<RanIt>& left, const reverse_iterator<RanIt>& right);template<class RanIt> reverse_iterator<RanIt> <B><A HREF="#operator+">operator+</A></B>( Diff off, const reverse_iterator<RanIt>& right);template<class Container> back_insert_iterator<Container> <B><A HREF="#back_inserter">back_inserter</A></B>(Container& cont);template<class Container> front_insert_iterator<Container> <B><A HREF="#front_inserter">front_inserter</A></B>(Container& cont);template<class Container, class Iter> insert_iterator<Container> <B><A HREF="#inserter">inserter</A></B>(Container& cont, Iter it);template<class InIt, class Diff> void <B><A HREF="#advance">advance</A></B>(InIt& it, Diff off);template<class Init> iterator_traits<InIt>::difference_type <B><A HREF="#distance">distance</A></B>(InIt first, InIt last); };</PRE><H2><A NAME="advance"><CODE>advance</CODE></A></H2><PRE>template<class InIt, class Diff> void <B>advance</B>(InIt& it, Diff off);</PRE><P>The template function effectively advances <CODE>it</CODE> byincrementing it <CODE>off</CODE> times. If <CODE>InIt</CODE> isa random-access iterator type, the function evaluates the expression<CODE>it += off</CODE>. Otherwise, it performs each incrementby evaluating <CODE>++it</CODE>. If <CODE>InIt</CODE> is aninput or forward iterator type, <CODE>off</CODE> must not be negative.</P><H2><A NAME="back_insert_iterator"><CODE>back_insert_iterator</CODE></A></H2><PRE>template<class Container> class <B>back_insert_iterator</B> : public iterator<output_iterator_tag, void, void, void, void> {public: typedef Container <B><A HREF="#back_insert_iterator::container_type">container_type</A></B>; typedef typename Container::reference <B><A HREF="#back_insert_iterator::reference">reference</A></B>; explicit <B><A HREF="#back_insert_iterator::back_insert_iterator">back_insert_iterator</A></B>(Container& cont); back_insert_iterator& <B><A HREF="#back_insert_iterator::operator=">operator=</A></B>(typename Container::const_reference val); back_insert_iterator& <B><A HREF="#back_insert_iterator::operator*">operator*</A></B>(); back_insert_iterator& <B><A HREF="#back_insert_iterator::operator++">operator++</A></B>(); back_insert_iterator <B><A HREF="#back_insert_iterator::operator++">operator++</A></B>(int);protected: Container *<B><A HREF="#back_insert_iterator::container">container</A></B>; };</PRE><P>The template class describes an output iterator object.It inserts elementsinto a container of type <B><CODE>Container</CODE></B>, which it accesses viathe protected pointer object it stores called<B><CODE><A NAME="back_insert_iterator::container">container</A></CODE></B>.The container must define:</P><UL><LI>the member type <B><CODE>const_reference</CODE></B>, which is the type ofa constant reference to an element of the sequence controlled by the container</LI><LI>the member type <B><CODE>reference</CODE></B>, which is the type ofa reference to an element of the sequence controlled by the container</LI><LI>the member type <B><CODE>value_type</CODE></B>, which is the type ofan element of the sequence controlled by the container</LI><LI>the member function <CODE><B>push_back</B>(value_type val)</CODE>,which appends a new element with value <CODE>val</CODE> to the end ofthe sequence</LI></UL><H3><A NAME="back_insert_iterator::back_insert_iterator"><CODE>back_insert_iterator::back_insert_iterator</CODE></A></H3><PRE>explicit <B>back_insert_iterator</B>(Container& cont);</PRE><P>The constructor initializes<CODE><A HREF="#back_insert_iterator::container">container</A></CODE>with <CODE>&cont</CODE>.</P><H3><A NAME="back_insert_iterator::container_type"><CODE>back_insert_iterator::container_type</CODE></A></H3><PRE>typedef Container <B>container_type</B>;</PRE><P>The type is a synonym for the template parameter <CODE>Container</CODE>.</P><H3><A NAME="back_insert_iterator::operator*"><CODE>back_insert_iterator::operator*</CODE></A></H3><PRE>back_insert_iterator& <B>operator*</B>();</PRE><P>The member function returns <CODE>*this</CODE>.</P><H3><A NAME="back_insert_iterator::operator++"><CODE>back_insert_iterator::operator++</CODE></A></H3><PRE>back_insert_iterator& <B>operator++</B>();back_insert_iterator <B>operator++</B>(int);</PRE><P>The member functions both return <CODE>*this</CODE>.</P><H3><A NAME="back_insert_iterator::operator="><CODE>back_insert_iterator::operator=</CODE></A></H3><PRE>back_insert_iterator& <B>operator=</B>(typename Container::const_reference val);</PRE><P>The member function evaluates<CODE><A HREF="#back_insert_iterator::container">container</A>->push_back(val)</CODE>, then returns <CODE>*this</CODE>-></P><H3><A NAME="back_insert_iterator::reference"><CODE>back_insert_iterator::reference</CODE></A></H3><PRE>typedef typename Container::reference <B>reference</B>;</PRE><P>The type describes a reference to an element of the sequencecontrolled by the associated container.</P><H2><A NAME="back_inserter"><CODE>back_inserter</CODE></A></H2><PRE>template<class Container> back_insert_iterator<Container> <B>back_inserter</B>(Container& cont);</PRE><P>The template function returns<CODE><A HREF="#back_insert_iterator::back_insert_iterator">back_insert_iterator</A><Container>(cont)</CODE>.</P><H2><A NAME="bidirectional_iterator_tag"><CODE>bidirectional_iterator_tag</CODE></A></H2><PRE>struct <B>bidirectional_iterator_tag</B> : public forward_iterator_tag { };</PRE><P>The type is the same as<CODE>iterator<Iter>::<A HREF="#iterator::iterator_category">iterator_category</A></CODE>when <CODE>Iter</CODE> describes an object that can serve as abidirectional iterator.</P><H2><A NAME="distance"><CODE>distance</CODE></A></H2><PRE>template<class Init> typename iterator_traits<InIt>::difference_type <B>distance</B>(InIt first, InIt last);</PRE><P>The template function sets a count <CODE>N</CODE> to zero. It theneffectively advances <CODE>first</CODE>and increments <CODE>N</CODE> until <CODE>first == last</CODE>.If <CODE>InIt</CODE> isa random-access iterator type, the function evaluates the expression<CODE>N += last - first</CODE>. Otherwise, it performs each iteratorincrement by evaluating <CODE>++first</CODE>.The function returns <CODE>N</CODE>.</P><H2><A NAME="forward_iterator_tag"><CODE>forward_iterator_tag</CODE></A></H2><PRE>struct <B>forward_iterator_tag</B> : public input_iterator_tag { };</PRE><P>The type is the same as<CODE>iterator<Iter>::<A HREF="#iterator::iterator_category">iterator_category</A></CODE>when <CODE>Iter</CODE> describes an object that can serve as aforward iterator.</P><H2><A NAME="front_insert_iterator"><CODE>front_insert_iterator</CODE></A></H2><PRE>template<class Container> class <B>front_insert_iterator</B> : public iterator<output_iterator_tag, void, void, void, void> {public: typedef Container <B><A HREF="#front_insert_iterator::container_type">container_type</A></B>; typedef typename Container::reference <B><A HREF="#front_insert_iterator::reference">reference</A></B>; explicit <B><A HREF="#front_insert_iterator::front_insert_iterator">front_insert_iterator</A></B>(Container& cont); front_insert_iterator& <B><A HREF="#front_insert_iterator::operator=">operator=</A></B>(typename Container::const_reference val); front_insert_iterator& <B><A HREF="#front_insert_iterator::operator*">operator*</A></B>(); front_insert_iterator& <B><A HREF="#front_insert_iterator::operator++">operator++</A></B>(); front_insert_iterator <B><A HREF="#front_insert_iterator::operator++">operator++</A></B>(int);protected: Container *<B><A HREF="#front_insert_iterator::container">container</A></B>; };</PRE><P>The template class describes an output iterator object.It inserts elementsinto a container of type <B><CODE>Container</CODE></B>, which it accesses viathe protected pointer object it stores called<B><CODE><A NAME="front_insert_iterator::container">container</A></CODE></B>.The container must define:</P><UL><LI>the member type <B><CODE>const_reference</CODE></B>, which is the type ofa constant reference to an element of the sequence controlled by the container</LI><LI>the member type <B><CODE>reference</CODE></B>, which is the type ofa reference to an element of the sequence controlled by the container</LI><LI>the member type <B><CODE>value_type</CODE></B>, which is the type ofan element of the sequence controlled by the container</LI><LI>the member function <CODE><B>push_front</B>(value_type val)</CODE>,which prepends a new element with value <CODE>val</CODE> to the beginning ofthe sequence</LI></UL>⌨️ 快捷键说明
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