Q156531: INFO: STL Sample for the remove Function

Article: Q156531
Product(s): Microsoft C Compiler
Version(s): 4.2,5.0,6.0
Operating System(s): 
Keyword(s): kbcode kbVC420 kbVC500 kbVC600 kbDSupport
Last Modified: 26-MAR-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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NOTE: Microsoft Visual C++ NET (2002) supported both the managed code model that is provided by the .NET Framework and the unmanaged native Windows code model. The information in this article applies to unmanaged Visual C++ code only.

SUMMARY
=======

The sample code below illustrates how to use the remove, begin, and end STL
functions in Visual C++.

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

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

     <algorithm>

Prototype
---------

     template<class ForwardIterator, class Type> inline
     ForwardIterator remove(ForwardIterator first,

                            ForwardIterator last,
                            const T& value)

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

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

The remove algorithm removes all elements that match value from the range (first,
last). It returns an iterator equal to last - N, where N = number of elements
removed. The last N elements of the range have undefined values. The size of the
container remains the same.

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

  ////////////////////////////////////////////////////////////////////// 
  // 
  // Compile options needed: /GX
  // 
  // remove.cpp : Illustrates how to use the remove function.
  // 
  // Functions:
  // 
  //   remove - remove all elements from the sequence that match value.
  //   begin - Returns an iterator that points to the first element in a
  //           sequence.
  //   end - Returns an iterator that points one past the end of a sequence.
  // 
  // Written by Kalindi Sanghrajka
  // of Microsoft Product Support Services,
  // Software Core Developer Support.
  // Copyright (c) 1996 Microsoft Corporation. All rights reserved.
  ////////////////////////////////////////////////////////////////////// 

  // disable warning C4786: symbol greater than 255 character,
  // okay to ignore

  #pragma warning(disable: 4786)

  #include <iostream>
  #include <vector>
  #include <algorithm>
  #include <functional>
  using namespace std;

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

  void main()

  {

      const int VECTOR_SIZE = 8 ;

      // Define a template class vector of integers
      typedef vector<int, allocator<int> > IntVector ;

      //Define an iterator for template class vector of integer
      typedef IntVector::iterator IntVectorIt ;

      IntVector Numbers(VECTOR_SIZE) ;   //vector containing numbers

      IntVectorIt start, end, it, last;

      start = Numbers.begin() ;   // location of first
                                  // element of Numbers

      end = Numbers.end() ;       // one past the location
                                  // last element of Numbers

      //Initialize vector Numbers
      Numbers[0] = 10 ;
      Numbers[1] = 20 ;
      Numbers[2] = 10 ;
      Numbers[3] = 15 ;
      Numbers[4] = 12 ;
      Numbers[5] = 7 ;
      Numbers[6] = 9 ;
      Numbers[7] = 10 ;

      cout << "Before calling remove" << endl ;

      // print content of Numbers
      cout << "Numbers { " ;
      for(it = start; it != end; it++)
          cout << *it << " " ;
      cout << " }\n" << endl ;

      // remove all elements from Numbers that match 10
       last = remove(start, end, 10) ;

      cout << "After calling remove" << endl ;

      // print content of Numbers
      cout << "Numbers { " ;
      for(it = start; it != end; it++)
          cout << *it << " " ;
      cout << " }\n" << endl ;

      //print number of elements removed from Numbers
      cout << "Total number of elements removed from Numbers = "
          << end - last << endl ;

      //print only the valid elements of Number
      cout << "Valid elements of Numbers { " ;
      for(it = start; it != last; it++)
          cout << *it << " " ;
      cout << " }\n" << endl ;

  }

Program Output is:

Before calling remove
Numbers { 10 20 10 15 12 7 9 10  }

After calling remove
Numbers { 20 15 12 7 9 7 9 10  }

Total number of elements removed from Numbers = 3
Valid elements of Numbers { 20 15 12 7 9  }

REFERENCES
==========

Visual C++, version 4.2, Visual C++ Books Online; click Visual C++ Books, C/C++,
and then Standard C++ Library Reference.

Additional query words: STL STLSample remove begin end kbcrt kbtemplate

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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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