<!--
    Licensed to the Apache Software  Foundation (ASF) under one or more
    contributor  license agreements.  See  the NOTICE  file distributed
    with  this  work  for  additional information  regarding  copyright
    ownership.   The ASF  licenses this  file to  you under  the Apache
    License, Version  2.0 (the  License); you may  not use  this file
    except in  compliance with the License.   You may obtain  a copy of
    the License at

    http://www.apache.org/licenses/LICENSE-2.0

    Unless required by applicable law or agreed to in writing, software
    distributed under the  License is distributed on an  "AS IS" BASIS,
    WITHOUT  WARRANTIES OR CONDITIONS  OF ANY  KIND, either  express or
    implied.   See  the License  for  the  specific language  governing
    permissions and limitations under the License.

    Copyright 1999-2007 Rogue Wave Software, Inc.
-->

<HTML>
<HEAD>
<TITLE>reverse()</TITLE>
<LINK REL=StyleSheet HREF="../rw.css" TYPE="text/css" TITLE="Apache stdcxx Stylesheet"></HEAD>
<BODY BGCOLOR=#FFFFFF>
<A HREF="return-temporary-buffer.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="reverse-copy.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>
<H2>reverse()</H2>
<P><B>Library:</B>&nbsp;&nbsp;<A HREF="2-9.html">Algorithms</A></P>

<PRE><HR><B><I>Function</I></B><HR></PRE>

<UL>
<LI><A HREF="#sec1">Local Index</A></LI>
<LI><A HREF="#sec2">Summary</A></LI>
<LI><A HREF="#sec3">Synopsis</A></LI>
<LI><A HREF="#sec4">Description</A></LI>
<LI><A HREF="#sec5">Complexity</A></LI>
<LI><A HREF="#sec6">Example</A></LI>
<LI><A HREF="#sec7">See Also</A></LI>
<LI><A HREF="#sec8">Standards Conformance</A></LI>
</UL>
<A NAME="sec1"><H3>Local Index</H3></A>
No Entries
<A NAME="sec2"><H3>Summary</H3></A>
<P>An algorithm that reverses the order of elements in a sequence</P>
<A NAME="sec3"><H3>Synopsis</H3></A>

<PRE>#include &lt;algorithm&gt;

namespace std {
  template &lt;class BidirectionalIterator&gt;
  void reverse(BidirectionalIterator start,
               BidirectionalIterator finish);
}
</PRE>
<A NAME="sec4"><H3>Description</H3></A>
<P>The algorithm <SAMP>reverse()</SAMP> reverses the elements in a sequence so that the last element becomes the new first element, and the first element becomes the new last. For each non-negative integer <SAMP>i &lt;= (finish - start)/2</SAMP>, <SAMP>reverse()</SAMP> applies <SAMP><A HREF="iter-swap.html">iter_swap()</A></SAMP> to all pairs of iterators <SAMP>start + I, (finish&nbsp;-&nbsp;I)&nbsp;- 1</SAMP>. </P>
<A NAME="sec5"><H3>Complexity</H3></A>
<P><SAMP>reverse()</SAMP> performs exactly <SAMP>(finish - start)/2</SAMP> swaps.</P>
<A NAME="sec6"><H3>Example</H3></A>

<UL><PRE>//
//  reverse.cpp
//

#include &lt;algorithm&gt;   // for reverse, reverse_copy
#include &lt;vector&gt;      // for vector
#include &lt;iostream&gt;    // for cout, endl
#include &lt;iterator&gt;    // for ostream_iterator


int main ()
{
    typedef std::vector&lt;int, std::allocator&lt;int&gt; &gt; Vector;
    typedef std::ostream_iterator&lt;int, char,
                                  std::char_traits&lt;char&gt; &gt;
            Iter;

    // Initialize a vector with an array of integers.
    const Vector::value_type a[] = { 1, 2, 3, 4, 5, 
                                     6, 7, 8, 9, 10 };

    Vector v (a + 0, a + sizeof a / sizeof *a);

    // Print out elements in original (sorted) order.
    std::cout &lt;&lt; "Elements before reverse: \n     ";
    std::copy (v.begin (), v.end (), Iter (std::cout, " "));

    // Reverse the ordering.
    std::reverse (v.begin (), v.end ());

    // Print out the reversed elements.
    std::cout &lt;&lt; "\n\nElements after reverse: \n     ";
    std::copy (v.begin (), v.end (), Iter (std::cout, " "));

    std::cout &lt;&lt; "\n\nA reverse_copy to cout: \n     ";
    std::reverse_copy (v.begin (), v.end (), 
                       Iter (std::cout, " "));
    std::cout &lt;&lt; std::endl;

    return 0;
}


Program Output:
</PRE></UL>
<UL><PRE>Elements before reverse: 
     1 2 3 4 5 6 7 8 9 10 

Elements after reverse: 
     10 9 8 7 6 5 4 3 2 1 

A reverse_copy to cout: 
     1 2 3 4 5 6 7 8 9 10 
</PRE></UL>
<A NAME="sec7"><H3>See Also</H3></A>
<P><SAMP><A HREF="reverse-copy.html">reverse_copy()</A></SAMP>, <SAMP><A HREF="swap.html">swap()</A></SAMP></P>
<A NAME="sec8"><H3>Standards Conformance</H3></A>
<P><I>ISO/IEC 14882:1998 -- International Standard for Information Systems -- Programming Language C++, Section 25.2.9</I></P>

<BR>
<HR>
<A HREF="return-temporary-buffer.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="reverse-copy.html"><IMG SRC="images/bnext.gif" WIDTH=20 HEIGHT=21 ALT="Next file" BORDER=O></A>

<!-- Google Analytics tracking code -->
<script src="http://www.google-analytics.com/urchin.js" type="text/javascript">
</script>
<script type="text/javascript">
    _uacct = "UA-1775151-1";
    urchinTracker();
</script>
<!-- end of Google Analytics tracking code -->

</BODY>
</HTML>