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

• The Standard C++ Library included with: - Microsoft Visual C++, 32-bit Editions, version 4.2

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 that 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();

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>

   #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.