DOCUMENT:Q156760  26-MAR-2002  [visualc]
TITLE   :STL Sample for deque::front and deque::back Functions
PRODUCT :Microsoft C Compiler
PROD/VER::4.2,5.0,6.0
OPER/SYS:
KEYWORDS:kbcode kbVC420 kbVC500 kbVC600 kbDSupport

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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 deque::front and deque::back
STL functions for the deque container class in Visual C++.

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

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

      < deque>

Prototype
---------

      reference front();
      const_reference front() const;

      reference back();
      const_reference back() const;

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
-----------

The member function front() returns a reference to the first element of the
controlled sequence, which must be non-empty.

The member function back() returns a reference to the last element of the
controlled sequence, which must be non-empty.

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

NOTE: In the first line of the sample code section, /GX is equivalent to /EHsc in
VC++ .NET and is set by default.

      ////////////////////////////////////////////////////////////////////// 
      // 
      // Compile options needed: -GX
      // 
      // deque.cpp :
      // 
      // Functions:
      // 
      //    front()
      // 
      //    back()
      // 
      // Written by Bobby Mattappally
      // of Microsoft Product Support Services,
      // Copyright (c) 1996 Microsoft Corporation. All rights reserved.
      ////////////////////////////////////////////////////////////////////// 

      /* Compile options needed:-GX
      */ 
      #include <iostream>
      #include <deque>
     
   #if _MSC_VER > 1020   // if VC++ version is > 4.2
      using namespace std;  // std c++ libs implemented in std
      #endif

      typedef deque<char, allocator<char> >  CHARDEQUE;
      void print_contents (CHARDEQUE  deque, char*);

      void main()
      {
          //create a  with  A, B, C and D
          CHARDEQUE  a;
          a.push_back('A');
          a.push_back('B');
          a.push_back('C');
          a.push_back('D');

          //print out the contents
          print_contents (a,"a");

          cout <<"The first element of a is " <<a.front() <<endl;

          cout <<"The last element of a is " <<a.back() <<endl;

          //now let us modify the first and last elements
          //using reference ,front() and back()

          CHARDEQUE::reference reffront=a.front();
          CHARDEQUE::reference refback=a.back();

          reffront='X';
          refback='Y';

           //print out the contents
           print_contents (a,"a");

          }

      //function to print the contents of deque
      void print_contents (CHARDEQUE  deque, char *name)
      {
          CHARDEQUE::iterator pdeque;

          cout <<"The contents of "<< name <<" : ";

              for(pdeque = deque.begin();
              pdeque != deque.end();
              pdeque++)
          {
              cout << *pdeque <<" " ;
          }
              cout<<endl;

      }

Program output is:

   The contents of a : A B C D

   The first element of a is A

   The last element of a is D

   The contents of a : X B C Y

REFERENCES
==========

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

Additional query words: STL STLSample deque front back reference

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

=============================================================================

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