Q168046: HOWTO: STL Sample for [list::rbegin, rend, reverse, rev_iterator

Article: Q168046
Product(s): Microsoft C Compiler
Version(s): 4.2,5.0,6.0
Operating System(s): 
Keyword(s): kbcode kbVC420 kbVC500 kbVC600
Last Modified: 29-APR-2002

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The information in this article applies to:

- The Standard C++ Library, used with:
   - Microsoft Visual C++, 32-bit Enterprise Edition, versions 4.2, 5.0, 6.0 
   - Microsoft Visual C++, 32-bit Professional Edition, versions 4.2, 5.0, 6.0 
   - Microsoft Visual C++, 32-bit Learning Edition, version 6.0 
   - Microsoft Visual C++.NET (2002) 
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SUMMARY
=======

The sample code below illustrates how to use the [list::rbegin, list::rend,
list::reverse_iterator, list::reverse] STL function(s) in Visual C++.

NOTE: There are some differences in the implementation of the Standard C++
Library components in Visual C++ version 4.2 versus later revisions. The
relevant sections of code below compile conditionally based upon the value of
_MSC_VER.

MORE INFORMATION
================

Required Header
---------------

     <list>
     <string>
     <iostream>

Prototype
---------

     const_reverse_iterator rbegin() const;
     reverse_iterator rbegin();
     const_reverse_iterator rend() const;
     reverse_iterator rend();
     typedef reverse_bidirectional_iterator<iterator,
         value_type, reference, A::types<T>::pointer,
             difference_type> reverse_iterator;
     void reverse();

NOTE: The class/parameter names in the prototype may not match the version in the
header file. Some have been modified to improve readability.

Description
-----------

This example shows how to iteratate through a list backwards. It also shows how
to reverse a list.

Sample Code
-----------

     ////////////////////////////////////////////////////////////////////// 
     // 
     // Compile options needed: -GX
     // 
     // rev.cpp :  This example shows how to iteratate through a list
     //            backwards.  It also shows how to reverse a list.
     // 
     // Functions:
     // 
     //  list::rbegin
     //  list::rend
     //  list::reverse_iterator
     //  list::reverse
     // 
     // Written by Andrew Bradnan
     // Copyright (c) 1996 Microsoft Corporation. All rights reserved.
     ////////////////////////////////////////////////////////////////////// 
     #pragma warning(disable:4786)
     #include <list>
     #include <string>
     #include <iostream>
     using namespace std;

     #if _MSC_VER > 1020   // if VC++ version is > 4.2
     using namespace std;  // std c++ libs implemented in std
     #endif

     typedef list<string, allocator<string> > LISTSTR;

     // We use this object so that list::sort() can sort in a different
     // order.Normally greater<> is used.  We override it here to switch to
     // less.
     struct less_str : greater<string> {
        bool operator()(const string& _X, const string& _Y) const
           {return (_X < _Y); }
        };

     void main()
     {
        LISTSTR test;
        LISTSTR::iterator i;
        LISTSTR::reverse_iterator r;

        test.push_back("one");
        test.push_back("two");
        test.push_back("three");

        // one two three
        cout << "Forwards" << endl << " ";
        for (i = test.begin(); i != test.end(); ++i)
           cout << *i << " ";
        cout << endl;

        // three two one
        cout << "Backwards" << endl << " ";
        for (r = test.rbegin(); r != test.rend(); ++r)
           cout << *r << " ";
        cout << endl;

        // Switch the order
        test.reverse();

        // three two one
        cout << "Reversed" << endl << " ";
        for (i = test.begin(); i != test.end(); ++i)
           cout << *i << " ";
        cout << endl;

        // sort alphabetically (decending by default)
        test.sort();

        // two three one
        cout << "Sorted descending" << endl << " ";
        for (i = test.begin(); i != test.end(); ++i)
           cout << *i << " ";
        cout << endl;

        test.sort(less_str());

        // One three two
        cout << "Sorted ascending" << endl << " ";
        for (i = test.begin(); i != test.end(); ++i)
           cout << *i << " ";
        cout << endl;
     }

Program Output
--------------

  Forwards
   one two three
  Backwards
   three two one
  Reversed
   three two one
  Sorted descending
   one three two
  Sorted ascending
   two three one

REFERENCES
==========

Visual C++ Books On Line: Visual C++ Books:C/C++:Standard C++ Library Reference.

Additional query words: STL STLSample [list::rbegin, list::rend, list::reverse_iterator, list::reverse]

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Keywords          : kbcode kbVC420 kbVC500 kbVC600 
Technology        : kbVCsearch kbAudDeveloper kbVCLibrary
Version           : :4.2,5.0,6.0
Issue type        : kbhowto

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