206 lines
7.9 KiB
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206 lines
7.9 KiB
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<HTML>
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<HEAD>
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<TITLE>reverse_iterator</TITLE>
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<LINK REL=StyleSheet HREF="../rw.css" TYPE="text/css" TITLE="Apache stdcxx Stylesheet"></HEAD>
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<BODY BGCOLOR=#FFFFFF>
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<A HREF="reverse-copy.html"><IMG SRC="images/bprev.gif" WIDTH=20 HEIGHT=21 ALT="Previous file" BORDER=O></A><A HREF="noframes.html"><IMG SRC="images/btop.gif" WIDTH=56 HEIGHT=21 ALT="Top of Document" BORDER=O></A><A HREF="booktoc.html"><IMG SRC="images/btoc.gif" WIDTH=56 HEIGHT=21 ALT="Contents" BORDER=O></A><A HREF="tindex.html"><IMG SRC="images/bindex.gif" WIDTH=56 HEIGHT=21 ALT="Index page" BORDER=O></A><A HREF="rotate.html"><IMG SRC="images/bnext.gif" WIDTH=25 HEIGHT=21 ALT="Next file" BORDER=O></A><DIV CLASS="DOCUMENTNAME"><B>Apache C++ Standard Library Reference Guide</B></DIV>
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<H2>reverse_iterator</H2>
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<P><B>Library:</B> <A HREF="2-8.html">Iterators</A></P>
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<PRE><HR><B><I>Does not inherit</I></B><HR></PRE>
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<UL>
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<LI><A HREF="#sec1">Local Index</A></LI>
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<LI><A HREF="#sec2">Summary</A></LI>
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<LI><A HREF="#sec3">Synopsis</A></LI>
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<LI><A HREF="#sec4">Description</A></LI>
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<LI><A HREF="#sec5">Interface</A></LI>
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<LI><A HREF="#sec6">Example</A></LI>
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<LI><A HREF="#sec7">Complexity</A></LI>
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<LI><A HREF="#sec8">See Also</A></LI>
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<LI><A HREF="#sec9">Standards Conformance</A></LI>
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</UL>
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<A NAME="sec1"><H3>Local Index</H3></A>
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No Entries
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<A NAME="sec2"><H3>Summary</H3></A>
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<P>An iterator adaptor that traverses a collection backwards.</P>
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<A NAME="sec3"><H3>Synopsis</H3></A>
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<PRE>#include <iterator>
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namespace std {
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template <class Iterator>
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class <B>reverse_iterator</B>;
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}
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</PRE>
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<A NAME="sec4"><H3>Description</H3></A>
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<P>The class template <B><I>reverse_iterator</I></B> adapts any random access iterator or <B><I>bidirectional_iterator</I></B> to facilitate the traversal of collections in the opposite direction. The fundamental relationship between a reverse iterator and its corresponding iterator <SAMP>i</SAMP> is established by the identity:</P>
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<UL><PRE>
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&*(reverse_iterator(i)) == &*(i - 1);
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</PRE></UL>
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<P>This mapping is necessary because, while an iterator past the end of a sequence is still valid but not dereferenceable, there might not be a valid iterator before its beginning.</P>
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<A NAME="sec5"><H3>Interface</H3></A>
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<UL><PRE>namespace std {
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template <class Iterator>
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class reverse_iterator
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: public iterator
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<typename iterator_traits<iterator>::iterator_category,
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<typename iterator_traits<iterator>::value_type,
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<typename iterator_traits<iterator>::difference_type,
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<typename iterator_traits<iterator>::pointer,
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<typename iterator_traits<iterator>::reference>
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{
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public:
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typedef Iterator iterator_type;
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reverse_iterator();
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explicit reverse_iterator(iterator_type);
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iterator_type base();
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reference operator*();
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reverse_iterator& operator++();
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reverse_iterator operator++(int);
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reverse_iterator& operator--();
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reverse_iterator operator--(int);
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reverse_iterator operator+ (difference_type) const;
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reverse_iterator& operator+= (difference_type);
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reverse_iterator operator- (difference_type) const;
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reverse_iterator& operator-= (difference_type);
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reference operator[] (difference_type) const;
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};
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// Nonmember Operators
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template <class Iterator>
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bool operator== (const reverse_iterator<Iterator>&,
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const reverse_iterator<Iterator>&);
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template <class Iterator>
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bool operator!= (const reverse_iterator<Iterator>&,
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const reverse_iterator<Iterator>&);
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template <class Iterator>
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bool operator< (const reverse_iterator<Iterator>&,
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const reverse_iterator<Iterator>&);
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template <class Iterator>
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bool operator> (const reverse_iterator<Iterator>&,
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const reverse_iterator<Iterator>&);
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template <class Iterator>
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bool operator<= (const reverse_iterator<Iterator>&,
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const reverse_iterator<Iterator>&);
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template <class Iterator>
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bool operator>= (const reverse_iterator<Iterator>&,
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const reverse_iterator<Iterator>&);
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template <class Iterator>
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typename reverse_iterator<Iterator>::difference_type
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operator- (const reverse_iterator<Iterator>&,
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const reverse_iterator<Iterator>&);
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template <class Iterator>
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reverse_iterator<Iterator>
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operator+ (
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typename reverse_iterator<Iterator>::difference_type,
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const reverse_iterator<Iterator>&);
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}
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</PRE></UL>
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<A NAME="sec6"><H3>Example</H3></A>
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<UL><PRE>//
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// rev_itr.cpp
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//
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#include <iostream> // for cout, endl
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#include <vector> // for vector
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int main ()
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{
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typedef std::vector<int, std::allocator<int> > Vector;
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// Initialize a vector using an array.
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const Vector::value_type arr[] = { 3, 4, 7, 8 };
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const Vector v (arr + 0, arr + sizeof arr / sizeof *arr);
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// Output the original vector.
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std::cout << "Traversing vector with iterator: \n ";
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for (Vector::const_iterator i = v.begin ();
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i != v.end (); ++i)
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std::cout << *i << " ";
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// Output the vector backwards.
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std::cout << "\n\nSame vector, same loop, "
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<< "reverse_iterator: \n ";
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for (Vector::const_reverse_iterator j (v.end ());
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j != Vector::const_reverse_iterator (v.begin ());
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++j)
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std::cout << *j << " ";
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std::cout << std::endl;
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return 0;
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}
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Program Output:
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</PRE></UL>
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<UL><PRE>Traversing vector with iterator:
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3 4 7 8
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Same vector, same loop, reverse_iterator:
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8 7 4 3
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</PRE></UL>
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<A NAME="sec7"><H3>Complexity</H3></A>
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<P>All iterator operations are required to take at most amortized constant time.</P>
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<A NAME="sec8"><H3>See Also</H3></A>
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<P><A HREF="iterators.html">Iterators</A></P>
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<A NAME="sec9"><H3>Standards Conformance</H3></A>
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<P><I>ISO/IEC 14882:1998 -- International Standard for Information Systems -- Programming Language C++, Section 24.4.1.1</I></P>
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<BR>
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<HR>
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